A STUDY ON THE PROCESSING OF WHEAT-POTATO-CARROT COMPOSITE FLOUR CAKE

A Thesis

By

MD. REZAUL KARIM

Examination Roll No. 11 AEFT JD 02 M

Registration No. 33662

Session: 2006- 2007

Semester: July-December 2012

MASTER OF SCIENCE (MS)

IN

FOOD ENGINEERING

DEPARTMENT OF FOOD TECHNOLOGY AND RURAL INDUSTRIES

BANGLADESH AGRICULTURAL UNIVERSITY

MYMENSINGH

DECEMBER 2012

A STUDY ON THE PROCESSING OF WHEAT-POTATO-CARROT COMPOSITE FLOUR CAKE

A Thesis

Submitted to the Department of Food Technology and Rural Industries Bangladesh Agricultural University, Mymensingh

in partial fulfillment of the requirements for the degree of

MASTER OF SCIENCE (MS) IN

FOOD ENGINEERING

BY

MD. REZAUL KARIM

Examination Roll No. 11 AEFT JD 02 M

Registration No. 33662

Session: 2006-07

Semester: July-December 2012

DEPARTMENT OF FOOD TECHNOLOGY AND RURAL INDUSTRIES

BANGLADESH AGRICULTURAL UNIVERSITY

MYMENSINGH

DECEMBER 2012

A STUDY ON THE PROCESSING OF WHEAT-POTATO-CARROT COMPOSITE FLOUR CAKE

A Thesis

By

MD. REZAUL KARIM

Examination Roll No. 11 AEFT JD 02 M

Registration No. 33662

Session: 2006-07

Semester: July-December 2012

Approved as to style and contents by

....................................................... (Prof. Dr. Md. Abdul Alim)

Chairman Examination Committee

And Head, Department of Food Technology and Rural Industries

Bangladesh Agricultural University Mymensingh

DECEMBER 2012

.…………………………………........

(Dr. Abdullah Iqbal) Supervisor

………………………………… (Prof. Dr. Md. Nazrul Islam)

Co-Supervisor

DEDICATED

TO

MY BELOVED PARENTS

60

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66

Appendix -I

Table 1.1 Rating score for color of cakes prepared from different levels of composite

flour

*Hedonic Scale used: 1=Dislike extremely, 2=Dislike very much, 3=Dislike, 4=Dislike

slightly, 5=Neither like or dislike, 6=Like slightly, 7=Like moderately, 8=Like very much,

9=Like extremely.

No. of Taster Sample No. Total

S S1 S2 S3 4

1. 6 6 5 6 23

2. 6 7 8 9 30

3. 5 6 6 7 24

4. 7 7 8 8 30

5. 5 9 7 7 28

6. 5 7 7 8 27

7. 5 7 9 8 29

8. 7 7 8 8 30

9. 7 6 6 7 26

10. 6 5 7 8 26

Total 59 67 71 76 273

Mean 5.9 6.7 7.1 7.6

67

Table 1.2 Analysis Of Variance (ANOVA) for color

Coefficient of Variation: 13.16%

Table 1.3 Duncan’s Multiple Range Test (DMRT) for color

LSD value = 0.8238 (p< 0.05)

S_ = 0.2839 at alpha = 0.05 x

Sample code Original order of

means

Sample code Ranking order of

means

1 5.900 4 C 7.600A

2 6.700 3 BC 7.100AB

3 7.100 2 AB 6.700BC

4 7.600 1 A 5.900C

Source of

variance

Degree of

freedom

Sum of

squares

Mean

squares

F-value Probability

Calculated Tabulated

Replication

9 14.525 1.614 2.0011 2.22

0.0791

Factor A 3 15.475 5.158 6.3961 2.50 0.0020

Error 27 21.775 0.806

Total 39 51.775

68

Appendix –II

Table 2.1 Rating score for flavor of cakes prepared from different levels of composite

flour

*Hedonic Scale used: 1=Dislike extremely, 2=Dislike very much, 3=Dislike, 4=Dislike

slightly, 5=Neither like or dislike, 6=Like slightly, 7=Like moderately, 8=Like very much,

9=Like extremely.

No. of Taster Sample No. Total

S S1 S2 S3 4

1. 6 7 5 7 25

2. 6 7 6 9 28

3. 5 6 7 8 26

4. 7 6 7 8 28

5. 7 6 7 8 28

6. 6 7 8 9 30

7. 5 8 7 7 27

8. 5 8 9 7 29

9. 6 6 6 7 25

10. 7 5 6 8 26

Total 60 66 68 78 272

Mean 6.0 6.6 6.8 7.8

69

Table 2.2 Analysis Of Variance (ANOVA) for flavor

Coefficient of Variation: 14.21%

Table 2.3 Duncan’s Multiple Range Test (DMRT) for flavor

LSD value = 0.8863 (p< 0.05)

S_ = 0.3055 at alpha = 0.05 x

Sample code Original order of

means

Sample code Ranking order of

means

1 6.000 4 B 7.800A

2 6.600 3 B 6.800B

3 6.800 2 B 6.600B

4 7.800 1 A 6.000B

Source of

variance

Degree of

freedom

Sum of

squares

Mean

squares

F-value Probability

Calculated Tabulated

Replication 9 6.400 0.711 0.7619 2.22 0.0913

Factor A 3 16.800 5.600 6.0000 2.50 0.0029

Error 27 25.200 0.933

Total 39 48.400

70

Appendix -III

Table 3.1 Rating score for texture of cakes prepared from different levels of composite

flours

*Hedonic scale used: 1=Dislike extremely, 2=Dislike very much, 3=Dislike, 4=Dislike

slightly, 5=Neither like or dislike, 6=Like slightly, 7=Like moderately, 8=Like very much,

9=Like extremely.

No. of Taster Sample No. Total

S S1 S2 S3 4

1. 7 5 5 7 24

2. 6 7 7 9 29

3. 5 5 7 8 25

4. 7 5 7 7 26

5. 5 6 9 9 29

6. 6 8 8 9 31

7. 6 7 8 9 30

8. 7 7 7 8 29

9. 7 5 6 7 25

10. 5 5 6 8 24

Total 61 60 70 81 272

Mean 6.1 6.0 7.0 8.1

71

Table 3.2 Analysis Of Variance (ANOVA) for texture

Coefficient of Variation: 13.24%

Table 3.3 Duncan’s Multiple Range Test (DMRT) for texture

LSD value = 0.8264 (p< 0.05)

S_ = 0.2956 at alpha = 0.05 x

Sample code Original order of

means

Sample code Ranking order of

means

1 6.100 4 C 8.100A

2 6.000 3 C 7.000B

3 7.000 1 B 6.100C

4 8.100 2 A 6.000C

Source of

variance

Degree

of

freedom

Sum of

squares

Mean

squares

F-value Probability

Calculated Tabulated

Replication 9 15.900 1.767 2.1781 2.22 0.0571

Factor A 3 28.600 9.533 11.7534 2.50 0.0000

Error 27 21.900 0.811

Total 39 66.400

72

Appendix -IV

Table 4.1 Rating score for overall acceptability of cakes prepared from different levels

of composite flours

*Hedonic scale used: 1=Dislike extremely, 2=Dislike very much, 3=Dislike, 4=Dislike

slightly, 5=Neither like or dislike, 6=Like slightly, 7=Like moderately, 8=Like very much,

9=Like extremely.

No. of Taster Sample No. Total

S S1 S2 S3 4

1. 6 5 5 6 22

2. 7 7 8 9 31

3. 5 6 7 8 26

4. 7 5 7 8 27

5. 5 5 9 8 27

6. 6 7 8 9 30

7. 6 8 8 9 31

8. 6 9 8 8 31

9. 7 5 6 7 25

10. 5 5 6 8 24

Total 60 62 72 80 274

Mean 6.0 6.2 7.2 8.0

73

Table 4.2 Analysis Of Variance (ANOVA) for overall acceptability

Coefficient of variation: 13.65%

Table 4.3 Duncan’s Multiple Range Test (DMRT) for overall acceptability

LSD value = 0.8579 (p< 0.05)

S_ = 0.2956 at alpha = 0.050 x

Sample code Original order of

means

Sample code Ranking order of

means

1 6.000 4 B 8.000A

2 6.200 3 B 7.200A

3 7.200 2 A 6.200B

4 8.000 1 A 6.000B

Source of

variance

Degree

of

freedom

Sum of

squares

Mean

squares

F-value Probability

Calculated Tabulated

Replication 9 23.600 2.622 3.0000 2.22 0.0130

Factor A 3 25.900 8.633 9.8771 2.50 0.0001

Error 27 23.600 0.874

Total 39 73.100

v

ACKNOWLEDGEMENT Thanks almighty Allah who enabled me to peruse my higher studies in Food Engineering discipline as well as to submit the manuscript for the degree of MS in Food Engineering in the Department of Food Technology and Rural Industries, Bangladesh Agricultural University, Mymensingh, Bangladesh. I feel great pleasure in expressing my deep sense of gratitude, heartfelt indebtedness and profound respect to my honorable Supervisor Assistant Professor Dr. Abdullah Iqbal and Co-supervisor Professor Dr. Md. Nazrul Islam, Department of Food Technology and Rural Industries, Bangladesh Agricultural University, Mymensingh for their scholastic guidance, valuable instruction, generous help and encouragement throughout the course of my research work and during writing up the manuscript. I would like to extend my deep sense of gratitude and indebtedness to all of my respected teachers of the department of Food Technology and Rural Industries for their tremendous help, co-operation, advice and constructive criticism throughout the period of research work as well as in the preparation of the thesis manuscript. Cordial thanks and sincere appreciation are due to all laboratory and office staff of the department of Food Technology and Rural Industries, Bangladesh Agricultural University, Mymensingh, for their generous help and kind co-operation during the period of investigation to execute and to complete the research work. Profound thanks and appreciation are due to my intimate friends and all other well-wishers for their support, friendly co-operation and constant encouragement in preparing the manuscript. Finally, I would like to acknowledge my heartfelt indebtedness to my beloved parents, brothers, sisters and relatives for their continuous inspiration, sacrifices and blessing that opened the gate and paved to way for my higher studies. December 2012 The Author

vi

ABSTRACT

The study reports on the development of new types of cakes using composite flour consisting of wheat, potato and carrot flour. The cakes were prepared by standard formulation. The flours used in the cake preparation were analyzed for proximate composition. Three samples of composite flour cakes containing 5, 15 and 25% potato flour and 25, 15 and 5% carrot flour in combination with wheat flour (70%) were processed. The properties of composite cakes were evaluating in terms of volume, moisture content, weight, and crumb and crust characteristics. The cake supplemented with high level of potato flour and low level of carrot flour (composite) had significantly improved the cake weight and moisture content than those with other level of composite flour. Volume and specific volume of composite cakes were affected with varying potato-carrot flour mixing ratio in composite flour. Crumb and crust quality, symmetry and bloom of the cake containing 25% potato and 5% carrot flour was significantly better than other cakes containing composite flour. The cakes samples were analyzed for proximate composition. Higher amount of moisture, protein, fat, ash and crude fiber content were observed in composite flour cakes as compared to control cake (with only wheat flour). The cakes containing different levels of composite flour were evaluated for their sensory attributes by a panel of 10 tasters. The overall acceptability of the composite cake sample incorporating 70% wheat, 25% potato and 5% carrot flour was the most acceptable and significantly different from other cake samples including overall acceptability as far as quality factors are concerned.

Finally, the storage stability of composite cake packaged with single layer polythene was evaluated in terms of moisture uptake by storing it in room temperature (300C) and refrigeration temperature (50C). The composite cake stored in refrigeration temperature (shelf-life 6 days) provided longer storage stability than that of room temperature (shelf-life 3 days).

vii

CONTENTS

CHAPTR TITLE PAGE

NO.

ACKNOWLEDGEMENT V

ABSTRACT Vi

CONTENTS Vii

LIST OF TABLES Xi

LIST OF FIGURES Xii

LIST OF APPENDICES Xiii

1 INTRODUCTION 1-3

2 REVIEW AND LITERATURE 4-25

2.1 Wheat 4

2.1.1 Production and storage of wheat 4

2.1.2 Nutrient content and chemical composition of wheat 5

2.1.3 Nutrient content and chemical composition of wheat flour 5

2.1.4 Processing and use of wheat 6

2.2 Potato 6

2.2.1 Production and storage of potato 6

2.2.2 Nutrient content and chemical composition of potato 7

2.2.3 Nutrient content and chemical composition of potato flour 8

2.2.4 Processing and use of potato 8

2.3 Carrot 9

2.3.1 Production and storage of carrot 9

2.3.2 Nutrient content and chemical composition of carrot 10

2.3.3. Nutrient content and chemical composition of carrot flour 10

2.3.4. Processing and use of carrot 11

2.4 Composite flours 11

2.4.1 Composite flour goods 11

2.4.1.1 Bread and small baked goods 12

2.4.1.2 Pastry goods 12

2.4.1.3 Pasta 12

viii

CONTENTS (Continued)

CHAPTR TITLE PAGE

NO.

2.4.2 Technical problems at the bakery 12

2.4.3 Examples of recipes for various baked goods made

from composite flours

13

2.4.3.1 Bread and small baked products 13

2.4.3.2 Pastry goods 14

2.4.4 Nutritional value of composite baked goods 14

2.4.5 Treatment of composite flours 15

2.5 Major cake ingredients 17

2.5.1 Cake flour 17

2.5.2 Sugar 17

2.5.3 Shortening 18

2.5.4 Eggs 18

2.6 Cake making functions 19

2.6.1 Mixing 19

2.6.2 Evenly dispersion of ingredients 19

2.6.3 Properly aeration of batter 19

2.7 Mixing methods 20

2.7.1 Multistage mixing 20

2.7.2 Continuous mixing 21

2.8 Factors involved in cake processing 22

2.8.1 Batter temperature 22

2.8.2 Specific gravity 23

2.8.3 Scaling 23

2.8.4 Floor time 23

2.8.5 Baking 24

2.9 Effects of changing ingredients level on cake batter 25

ix

CONTENTS (Continued)

CHAPTR TITLE PAGE

NO. 3 MATERIALS AND METHODS 26-36

3.1 Materials 26

3.2 Methods 26

3.2.1 Procedures for Preparation of potato flour 26

3.2.2 Procedures for Preparation of carrot flour 28

3.2.3 Chemical analysis of fresh potato, carrot and wheat flour 28

3.2.3.1 Moisture 29

3.2.3.2 Protein 29

3.2.3.3 Ash 30

3.2.3.4 Fat 30

3.2.3.5 Crude fiber 31

3.2.3.6 Total carbohydrate 32

3.2.4 Product development 32

3.2.4.1 Formulation of cake by incorporating composite flour 32

3.2.4.2 Procedures for Preparation of composite cake 33

3.2.5 Chemical analysis of cakes containing composite flour 35

3.2.6 Evaluation of cake by objective analysis 35

3.2.7 Evaluation of effect of various levels of composite flour on

cake quality

35

3.2.8 Subjective (sensory) evaluation of cake 35

3.2.9 Observation on storage stability of composite cake 36

4 RESULTS AND DISCUSSION 37-55

4.1 Proximate composition of wheat, potato and carrot flour 37

4.2 The effect of composite flour on cake properties 38

4.2.1 Physical properties of cake 38

4.2.1.1 Cake volume 38

4.2.1.2 Weights of cake 41

4.2.1.3 Specific volume of cakes 41

4.2.1.4 Moisture contents of cakes 44

x

CONTENTS (Continued)

CHAPTR TITLE PAGE

NO.

4.2.2 Effects of composite flour on external and internal

characteristics of cakes

46

4.2.2.1 External characteristics of cake 46

4.2.2.1.1 Symmetry and bloom characteristics 46

4.2.2.1.2 Crust characteristics 46

4.2.2.1.2.1 Color of crust 46

4.2.2.1.2.2 Consistency of crust 46

4.2.2.2 Internal (crumb) characteristics of cakes 47

4.2.2.2.1 Color 47

4.2.2.2.2 Crumb texture 47

4.2.2.2.3 Crumb flavor 49

4.2.2.2.4 Crumb grain 49

4.3 The effect of composite flour on the composition of plain cake 49

4.3.1 Moisture content 50

4.3.2 Protein 50

4.3.3 Fat 50

4.3.4 Ash 51

4.3.5 Crude fiber 52

4.3.6 Total carbohydrate 52

4.4 Sensory evaluation of the cakes containing different level of

composite flour

53

4.5 Storage study of wheat-potato-carrot composite cake 55

5 SUMMARY AND CONCLUSION 57-59

REFERENCES 60-65

APPENDICES 66-74

xi

LIST OF TABLES

TABLE TITLE PAGE

NO.

2.1 Proximate analysis of potato 8

2.2 Cultivated area and production of wheat, potato and carrot in Bangladesh per year

9

2.3 Recipe for bread / small baked products with 70% wheat flour 13

2.4 Biscuit recipe with 70% wheat flour 14

2.5 Nutritional evaluation of various bread types made from composite flour

15

2.6 Influence of flour treatment and gelatinized starch on loaf volume of

composite flour from cassava starch and wheat flour (50/50 %)

16

2.7 Multistage mixing methods 21

2.8 Temperatures and specific gravity in various cake batters 22

2.9 Scaling for various weights of cakes 23

2.10 Typical bake time and temperature for cake variety 24

3.1 Basic formulation for preparation of plain cake and composite flour cakes (on 100 g flour basis)

32

4.1 Approximate composition of wheat, potato, and carrot flour 37

4.2 Effects of composite flour level on the volume, weight and moisture content of cake

44

4.3 Effects of composite flour (composite) on symmetry, crust and crumb characteristics of cake

48

4.4 Composition of cakes containing different levels of composite flour 51

4.5 Mean sensory scores of control cake and the cakes containing composite flour (wheat, potato and carrot flour)

54

4.6 The effect of normal and refrigeration condition on moisture content of composite cake

55

xii

LIST OF FIGURES

FIGURE TITLE PAGE

NO.

3.1 Schematic diagram for preparation of potato flour 27

3.2 Schematic diagram for preparation of composite cake 34

4.1 Physical appearance of control cake and composite cakes 39

4.2 Effect of potato-carrot mixed flour on composite cake volume 40

4.3 Effect of potato- carrot mixed flour on weight of composite cake 42

4.4 Effect of potato-carrot mixed flour on specific volume of composite cake

43

4.5 Effect of potato-carrot mixed flour on moisture content of composite cake

45

4.6 Effect of normal and refrigeration storage condition on moisture uptake of composite cake during storage

56

xiii

LIST OF APPENDICES

APPENDIX TITLE PAGE

NO.

I 66-67

1.1 Rating score for color of cakes prepared from different levels of

composite flour

66

1.2 Analysis Of Variance (ANOVA) for color 67

1.3 Duncan's Multiple Range Test (DMRT) for color 67

II 68-69

2.1 Rating score for flavor of cakes prepared from different levels of

composite flour

68

2.2 Analysis Of Variance (ANOVA) for flavor 69

2.3 Duncan's Multiple Range Test (DMRT) for flavor 69

III 70-71

3.1 Rating score for texture of cakes prepared from different levels of

composite flours

70

3.2 Analysis Of Variance (ANOVA) for texture 71

3.3 Duncan’s Multiple Range Test (DMRT) for texture 71

IV 72-73

4.1 Rating score for overall acceptability of cakes prepared from different

levels of composite flours

72

4.2 ANOVA (Analysis of variance) for overall acceptability 73

4.3 Duncan's Multiple Range Test (DMRT) for overall acceptability 73

V Taste testing of composite flour cake 74

1

Chapter 1 INTRODUCTION

Cereal and vegetable provide protein, carbohydrate, mineral and fiber. The composite flour

from cereal and vegetable source develop modified nutritional and sensory properties in

baked products. From the beginning of modern civilization consumption of various bakery

and confectionary products is the demand of time due to change in food habit. Cake is one of

the relished and palatable baked products prepared from flour, sugar, shortening, baking

powder, egg, essence as principal ingredients. Preparation of plain cake from wheat flour is

the conventional practice, but the use of composite flour was introduced by many researchers

and now-a-days is used in many developing countries to prepare nutritionally balanced cake.

The composite flour is the binary or ternary mixture of flours from some other sources with

wheat flour. The ingredients used in composite flours must take account of the raw materials

available in the country concerned.

Currently in Bangladesh, there is little potato, carrot and other vegetable industrial

processing, more than half of the potato and carrot produced is used in daily domestic

cooking purpose. Other potato and carrot products such as chips, starch, pickle, puff-puff,

chin-chin, buns, bread, jam, crisps, cake when introduced into the Bangladeshi food industry,

will enhance the demand for new potato-carrot varieties. Flour for the production of these

products is mainly obtained from wheat or other cereals and availability of adequate supply

of wheat flour has been a major political and economic issues. But Ngoddy and Onuoha

(1983) and Sanni et al., (2006) reported that composite flour can be made from legumes and

nuts, root and tubers such as yam, cassava, sweet potatoes and sensory qualities of yam and

potatoes flours has been has also been reported.

However, cake is a baked product from the mixture of flour, egg, butter, etc. which can be

taken as lunch, snack or stewed as breakfast (Aykroyl and Doughty, 1982). The production of

wheat compared to its demand is low and below domestic consumption level in Bangladesh,

thus there has been a large quantity of imported wheat flour which has resulted to loss in

foreign currency (Karibi, 1991). To this effect, composite flours have been developed to

supplement and reduce the loss resulting from our over dependence on wheat.

2

Chu and Michael (2004) stated that wheat flour is a powder made from the grinding of wheat

used for human consumption. Wheat varieties are called "clean," "white," or "brown" or

"hard" if they have high gluten content, and they are called "soft" or "weak" flour if gluten

content is low. Hard flour, or bread flour, is high in gluten, with 12% to 14% gluten content,

and has elastic toughness that holds its shape well once baked. Soft flour is comparatively

low in gluten and so results in a finer or crumbly texture. Soft flour is usually divided into

cake flour, which is the lowest in gluten, and pastry flour, which has slightly more gluten

than cake flour. In terms of the parts of the grain (the grass fruit) used in flour—the

endosperm or protein/starchy part, the germ or protein/fat/vitamin-rich part, and the bran or

fiber part—there are three general types of flour. White flour is made from the endosperm

only. Whole grain or whole meal flour is made from the entire grain, including bran,

endosperm and germ. A germ flour is made from the endosperm and germ, excluding the

bran.

Barry Farm Foods (1996) reported that potato flour is often confused with potato starch, but

the flour is produced from the entire dehydrated potato whereas potato starch is produced

from the starch only. It is also used as a thickener for soups, gravies, and sauces. Potato flour

is heavy and has a definite potato flavor. Made from the whole potato including the skin and

will absorb large amounts of water. It is not used as the main flour in baking as it will absorb

too much liquid and make the product gummy. Small amounts are used to increase water,

hold product together and so on. It is used as an ingredient in potato based recipes to enhance

the potato flavor and is often mixed with other types of flour for baking breads, cakes and

rolls.

Carrot is highly valued for its fleshy and delicious roots. It is micro in ß carotene; a precursor

of vitamin A (USDA, 1997). Elizabeth et al. (2012) stated that carrot flour has been included

in sweet recipes in Britain since mediaeval times. Because carrot provided a cheaper and

more easily available alternative to other sweeteners, their use was encouraged during the

Second World War, at the time of rationing. Carrot cake however, didn’t really take off in

popularity until the last quarter of the twentieth century; now it’ll be found it in every coffee

shop and tea room. Apart from the fact that it tastes delicious, there’s an air of

wholesomeness about carrot cake, a feeling that not only is it not bad for anybody but it’s

actually doing some one good!

In this study, wheat flour, potato flour and carrot flour will be used to prepare a palatable

composite cake with better physical, chemical and nutritional properties than plain cake. The

3

combination of wheat, potato and carrot flour is expected to give the higher baking properties

to the new product variety of cake. In order to analyze the various effects of composite flour

in processed cake different levels of potato and carrot flour will be used.

The major objectives of this study are:

i. To analyze the proximate composition of wheat, potato and carrot flours

ii. To prepare composite flour cake incorporating wheat, potato and carrot flours in the cake

formulation

iii. To examine the effects of various levels of composite flour on the quality, composition

and sensory attributes of cakes

iv. To assess the shelf-life of processed cake

4

Chapter 2 REVIEW OF LITERATURE

2.1 Wheat

2.1.1 Production and storage of wheat

Since the early 1970s, sustained government investment in irrigation facilities, rural

infrastructure, agricultural research, and extension services has helped Bangladeshi farmers

achieve dramatic increases in food production of wheat (Triticum spp.), the second most

important cereal, has also increased, although the country still imports significant quantities

of wheat to meet rapidly growing domestic demand. While the government of Bangladesh

continues to provide strong support to rice producers, its commitment to wheat farmers seems

less firm. Some policymakers have gone so far as to question whether support to wheat

should be scaled back, citing studies showing that wheat production is unprofitable and

represents an inefficient use of resources. But is wheat production in Bangladesh really

unprofitable for farmers and inefficient for the country? Researchers from the International

Food Policy Research Institute (IFPRI) and the International Maize and Wheat Improvement

Center (CIMMYT) recently examined the arguments for and against wheat production in

Bangladesh. In Wheat Production in Bangladesh: Technological, Economic, and Policy

Issues, Research Report 106, Michael L. Morris, Nuimuddin Chowdhury, and Craig Meisner

used a combination of financial and economic analysis to compare production of two

irrigated crops (wheat and boro rice) and three non-irrigated crops (wheat, oilseeds, and

pulses) in five wheat-growing zones. Their goal was to determine the extent to which

government policies and market failures may have driven a wedge between financial and

economic profitability. Whenever financial and economic profitability diverge, farmers

experience distorted incentives, and policy reforms may be necessary to encourage them to

act in ways that are consistent with efficiency objectives.

Wheat is widely cultivated as a cash crop because it produces a good yield per unit area,

grows well in a temperate climate even with a moderately short growing season. This grain is

grown on more land area than any other commercial crop. It is the major cereal crop of the

world, which marks firsts, followed by rice. In Bangladesh it is the second most important

food crop after rice. At present the crop is being cultivated in a total area of 3,58,022 hectares

5

of land producing 9,95,356 tons of wheat annually in Bangladesh (BBS, 2012). From 2010-

2011 to 2011-2012 area of wheat cultivation and production of wheat are shown in Table 2.2.

Swaminathan (2004) mentioned that wheat was a key factor enabling the emergence of city-

based societies at the start of civilization because it was one of the first crops that could be

easily cultivated on a large scale, and had the additional advantage of yielding a harvest that

provides long-term storage of food. Better seed storage and germination ability is another

20th century technological innovation. Wheat offers ease of grain storage and ease of

converting grain into flour for making edible, palatable, interesting and satisfying foods.

2.1.2 Nutrient content and chemical composition of wheat

Wheat provides more nourishment for humans than any other food source. Wheat is the most

important source of carbohydrate in a majority of countries. Wheat protein is easily digested

by nearly 99% of human population as is its starch. Wheat also contains a diversity of

minerals, vitamins and fats (lipids). With a small amount of animal or legume protein added,

a wheat-based meal is highly nutritious. The most common forms of wheat are white and red

wheat. However, other natural forms of wheat exist. For example, in the highlands of

Ethiopia grows purple wheat, a tetraploid species of wheat that is rich in anti-oxidants. Other

commercially minor but nutritionally promising species of naturally evolved wheat species

include black, yellow and blue wheat.

It contains carbohydrate and considerable amount of protein, mineral and vitamin. The grain

has 14.7% protein, 2.1% fat, 78.17% carbohydrate and 2.1 % mineral matter (Peterson,

1965).

2.1.3 Nutrient content and chemical composition of wheat flour

The nutritive value of 100% whole meal is the same as that of wheat, because whole meal

must (in the U.K) contain the whole of the products derived from the milling of clean wheat,

and no nutrients may be added to whole meal. Flours of lower extractions rates, viz. white

flour and brown flour, as milled, differ from wheat in nutritive value because of the removal

of varying amounts of bran, germ and outer endosperm, in which the concentration of

protein, minerals and vitamins is higher than in the inner endosperm. Nevertheless, in some

countries these differences in nutritive value are reduced by enrichment of white flour with

6

the most important of the nutrients that have been depleted, viz. vitamin B1 (thiamine),

riboflavin (vitamin B2

), nicotinic acid (niacin) and iron (Kent, 1984). Samuel (1960) reported

the composition of wheat flour as follows moisture 14%, protein 11.25%, fat 1.0%, ash 0.5%,

crude fiber 0.4% and total carbohydrate 72%.

2.1.4 Processing and use of wheat

Wheat yields versatile, high-quality flour that is widely used in baking. Most bread is made

with wheat flour, including many breads named for the other grains they contain like most

rye and oat breads. The popularity of foods made from wheat flour creates a large demand for

the grain, even in economies with significant food surpluses.

The whole grain can be milled to leave just the endosperm for white flour. The by-products

of this are bran and germ. Wheat flour has been defined as the product from grain of common

wheat by grinding or milling process in which the bran and germ are removed and the

remainder is comminuted to a suitable degree of fineness i.e. the particle size is about 140

micrometer (Kent, 1984). Wheat grain is a staple food used to make flour for leavened, flat

and steamed breads, biscuits, cookies, cakes, breakfast cereal, pasta, noodles, and couscous

and for fermentation to make beer, other alcoholic beverages, or biofuel.

2.2 Potato

2.2.1 Production and storage of potato

Potato (Solanum tuberosum) in one of the major food crops of the world. It ranks fourth in its

importance after, wheat and maize. Potato in one on the country, and contributes alone as

much as 55% of the total annual vegetable production (Anonymous, 1996).

Potato is now days commercially grown in almost all countries of the world. At present the

crop is being cultivated in a total area of 4,30,255 hectares of land producing 82,05,470 tons

of potato annually in Bangladesh (BBS, 2011). In Bangladesh, potato is a crop of great

economic significance. The crop is grown during winter months when most of the lands

remain fallow. Thus it competes with any other crop for land in the existing cropping pattern

of the country is nor significant. In Bangladesh from 2010-2011 to 2011-2012 area of potato

cultivation and production of potatoes are shown in Table 2.2.

7

Potato cultivation depends on several factors. Its growth, yield and quality are largely

influenced by soil and climate conditions as well as by different production practices. Katyal

and Chanda, (1995) reported cool temperatures of 18-20°C and proper moisture are important

for growth and formation of potato. They also reported that through grown on a variety of

soils, light loams, rich in humans are considered best. The soils should be well drained as the

tubers are very sensitive to excess of moisture and hence heavy soils are generally not

favored.

Storage life of potato tubers mainly depends on temperature and humidity which influence

evaporation respiration and sprout growth, and ultimately weight loss of tubers. Low

temperature (such as 4°C) and high humidity (such as 85-90%) in storage result in minimum

loss. Ahmad (1979) reported that the farmers of the North West part of Bangladesh use local

varieties of potato instead of the high yielding varieties only because they have a longer

dormancy and can be kept better for longer time even in ordinary storage. In Bangladesh,

farmers need to store their potatoes from March to September. By this time, a certain

percentage of tubers are damaged due to dehydration and rottage. Hashem (1979) reported

80% and Khan et al. (1984) reported 40.6% tuber loss in natural storage.

2.2.2 Nutrient content and chemical composition of potato

Watt and Merrill (1963) reported that the proximate composition of potato were about water

77.5%, protein 2%, fat 0.10%, ash 1% and total carbohydrate 19.2%.

Schwimmer and Burr (1967) reported that potato contains 77.5% water, 2% protein, 0.02%

fat, 0.10% carbohydrate, and 1% ash. It also contains ascorbic acid, niacin, thiamin (131),

iron and riboflavin. The proximate composition of potato is shown in Table 2.1.

8

Table 2.1 Proximate analysis of potato

Source: Schwimmer and Burr (1967)

2.2.3 Nutrient content and chemical composition of potato flour

Potato flour is a better source of starch, fiber and minerals. Schwimmer and Barr (1967)

reported that potato flour contained moisture 11.20% (wb), protein 5.50%, fat 0.85%, ash

2.40%, crude fiber 4.30% and total carbohydrate 75.75%.

2.2.4 Processing and use of potato

Frozen products, of which French fries take the lion share, chips and dried products are the

main kinds of processed food obtained from potato. Of them, the frozen products appear to

occupy the highest position, chips being the next and dried products occupy third position.

Though the frozen products appear to occupy the highest position in many countries, yet it is

an expensive process. It is not appropriate for Bangladesh. Except frozen products,

production of chips and dried products from potato appear to be relatively inexpensive.

Components Composition in

Average (%) Range (%)

Water 77.5 63.2-86.9

Total solid 22.5 13.1-36.8

Protein 2.0 0.7-4.6

Fat 0.1 0.02-0.96

Carbohydrate 19.2 13.3-30.53

Crude fiber 0.6 0.17-3.48

Ash 1.0 0.44-1.9

9

2.3 Carrot

2.3.1 Production and storage of carrot

Carrot (Daucus carota) is an important vegetable crop that belongs to the family apicaceae

(previously umbelliferae) and said to be originated in Mediterranean region (Banga, 1976;

Shinohara, 1984). It is mainly a temperate crop, grown during, spring through autumn in

temperate countries and during winter in tropical and sub-tropical countries of the world

(Banga, 1963). Carrot is grown successfully in Bangladesh during the Rabi season and at

temperature ranging between 10°C and 25°C. It is widely cultivated in Europe, Asia,

Northern Africa, North and South America. It grows in natural conditions in Southern Europe

and in West Asian countries (Rashid, 1983). At present the crop is being cultivated in a total

area of 36,397 hectares of land producing 4,18,983 tons of carrot annually in Bangladesh

(BBS, 2012). From 2011-2012 to 2011-2012 area of carrot cultivation and production of

carrot are shown in Table 2.2.

Table 2.2 Cultivated area and production of wheat, potato and carrot in Bangladesh per

year

Year / Crop

2010-2011 2011-2012

Area

(Hectares)

Total production

(M. Ton)

Area

(Hectares)

Total production

(M. Ton)

Wheat 3,73,708 9,72,085 3,58,022 9,95,356

Potato:

Local

HYV

74,583

3,85,614

8,69,787

74,56,602

72,794

3,57,461

8,37,967

73,67,503

Carrot 23,791 4,34,893 36,397 4,18,983

Source: BBS, Estimates of major and minor crops, 2012

Carrot is a seasonal vegetable and is available only for 2 to 3 months in a year. In peak season

a large quantity of carrot is grown in Bangladesh. But due to its high moisture content it

10

spoils quickly and at room temperature it can be stored only for 15-20 days. To supply

throughout the year. It is necessary to preserve carrot. It may be stored for up to five weeks in

cold storage by chilling method. However, chilling is an expensive method and requires

availability of cold storage. For long time preservation drying has been considered to be the

best method for developing countries like Bangladesh.

2.3.2 Nutrient content and chemical composition of carrot

Carrot is a very popular vegetable for its nutritive value and pleasing taste. It is highly valued

for its fleshy and delicious roots. It is micro in β carotene; a precursor of vitamin A. β

carotene is called antioxidant. This antioxidant prevents cancer and other metabolic diseases.

Carrot contains appreciable quantities of thiamin and riboflavin. It also contains a high

amount of sugar (Thompson and Kelly, 1957).

McGill (1961) observed that the nutritive value of carrot per 100g edible portion was as

stated hereunder : water, 82.8%; energy, 45 calories; protein, 1.2%; calcium, 42 mg; vitamin

A, 12,000 I.U; vitamin C, 4 mg; thiamin, 0.042 mg; riboflavin, 0.093 mg and niacin, 0.21 mg.

Schrader (1962) observed that the nutritive value of the carrot per 100g edible portion was

found to be: water, 88.2%; protein, 1.2%; fat, 0.3%; carbohydrate, 9.3%; vitamin a, 5500 i.0

and vitamin c, 7 mg. Carrot contains high quantities of carotene (10 mg/100g and appreciable

quantities of thiamine (0.04 mg/g) and riboflavin (0.05 mg/g) (Sharfuddin and Siddique,

1988). Kumar et al. (1978) also determined the nutrient content of carrot per 100 g edible

portion. The nutrient content was found to be: carbohydrate, 10.6g; protein, 0.19g; fat, 0.2g;

minerals, 1.1g; vitamin A, 3150 I.U; thiamine, 0.04 mg; riboflavin, 0.02 mg; oxalic acid, 5

mg; nicotinic acid, 0.06 mg; vitamin C, 3 mg; calories 47; calcium, 80 mg; magnesium, 14

mg; sodium, 35.6 mg; potassium, 106 mg; copper, 0.13 3 mg and sulphur, 27 mg.

2.3.3 Nutrient content and chemical composition of carrot flour

The dried carrot flour maintains the good quality of nutritional and chemical value. USDA

(1997) reported that carrot flour contained moisture 5.25%, protein 7%, fat 1.40%, ash

5.50%, crude fiber 2.25% and total carbohydrate 80.85%.

2.3.4 Processing and use of carrot

11

Catherine Renard (2012) reported that carrot is one of the important root vegetables rich in

bioactive compounds like carotenoids and dietary fibers with appreciable levels of several

other functional components having significant health-promoting properties. The

consumption of carrot and its products is increasing steadily due to its recognition as an

important source of natural antioxidants having anticancer activity. Apart from carrot roots

being traditionally used in salad and preparation of curries in India, these could commercially

be converted into nutritionally rich processed products like juice, concentrate, dried powder,

canned, preserve, candy, pickle, and gazrailla. Carrot pumice containing about 50% of β-

carotene could profitably be utilized for the supplementation of products like cake, bread,

biscuits and preparation of several types of functional products. The present review highlights

the nutritional composition, health promoting phytonutrients, functional properties, products

development and by-products utilization of carrot and carrot pumice along with their

potential application.

2.4 Composite flours

Composite flours are quite different from the ready-mixed flours familiar to millers and

bakers. Whereas ready-mixed flours contain all the non-perishable constituents of the recipe

for a certain baked product, composite flours are only a mixture of different vegetable flours

rich in starch or protein, with or without wheat flour, for certain groups of bakery products

(Chatelanat, 1973). This gives rise to the following definition:

“Composite flours are a mixture of flours from tubers rich in starch (e.g. cassava, yam,

potato) and /or protein-rich flours (e.g. soy, peanut) and /or cereals (e.g. maize, rice, millet,

buckwheat), with or without wheat flour.”

2.4.1 Composite flour goods

The goal of earlier research with composite flours was to save the largest possible percentage

of wheat flour in the production of certain baked products. The extent to which wheat flour

could be replaced by other vegetable flours naturally depended on the nature of the products

to be baked.

12

2.4.1.1 Bread and small baked goods

Trials with composite flours with and without wheat flour were carried out for this purpose.

Bugusu et al. (2001) referred that the composite flours containing wheat flour usually

consisted of 70% wheat flour, 25% maize/cassava starch and 5% soy flour. But there were

tests in which the composite flour contained no wheat flour at all - for example 70% cassava

flour or starch and 30% peanut and/or soy flour.

2.4.1.2 Pastry goods

In this field the focus of the tests was on producing hard and soft biscuits, with or without the

use of wheat flour. As a rule, the composite flour containing wheat consisted of 70-80%

wheat flour and 20 - 30% soy flour. In the cases no wheat was included, a mixture of 100%

sorghum/millet flour or 50% a cassava starch, 20% milk powder and 30% soy flour was used

(Jongh, 1961).

2.4.1.3 Pasta

Khalil et al. (2000) analyzed that the best quality was achieved with mixed flours consisting

of 60% cassava starch, 15% peanut flour and 25% wheat flour, or 20% maize, 40% soy and

30% wheat. But there were tests in which no wheat flour at all was used - only about 80%

pre-gelatinized maize flour and 20% soy flour. In Japan, noodles with or from buck¬wheat

(soba) are a traditional food, so nobody considers them to be made from composite flour,

which, by definition, is the case.

2.4.2 Technical problems at the bakery

Abdel-Kader (2000) showed that the use of composite flours with or without wheat gives rise

to technical problems in the production of baked goods. From the baker's point of view the

most important component of wheat flour is the protein of the gluten that plays a decisive role

in dough formation, gas retention and the structure of the crumb. If flour mixtures containing

little or no wheat are used, certain tricks have to be employed to achieve a properly leavened

product in the end. In 1954 Rotsch, and in 1961 Jongh, pointed out that better dough

structures and also better leavening of the bread can be achieved by using substances such as

pre-gelatinized flour and /or emulsifiers when working with composite flours with or without

13

wheat. Besides monoglycerides (0.5 - 1.0%), calcium and sodium stearoyl lactate (CSL and

SSL) were used successfully at a dose of 0.5- 1.0% (flour basis). Carboxymethyl cellulose,

alginate, guar, carob gum and also pre-gelatinized potato starch were used as binding agents.

The limit for the addition of cassava/ maize/ rice to wheat flour for bread and small baked

products is at least 50 - 80% wheat flour. The percentage depends on the baking quality of the

imported wheat flour concerned. In the case of biscuits and cakes it is possible to replace

wheat flour completely.

2.4.3 Example of recipes for various baked goods made from composite flours

The following are a few typical examples of the numerous recipes published in the 1960 s

and 1970 s.

2.4.3.1 Bread and small baked products

Table 2.3 contains a recipe for bread and small baked products based on 70% wheat flour.

The flour mixture is supplemented with 25% maize or cassava starch or flour and 5% soy

flour. The emulsifier used is CSL in the amount of 0.5% total flour. Table 2.4 is a

formulation for biscuit recipe with 70% wheat flour and 30% soy flour. In this case the

emulsifier used is CSL at a dose of 1% of the total amount of flour (Bugusu et al. 2001;

Anon, 2000).

Table 2.3 Recipe for bread / small baked products with 70% wheat flour

Component %

Wheat flour 70

Maize and/or cassava starch/flour 25

Soy flour 5

Sugar 4

Yeast 2

Salt 2

CSL 0.5 Water 50-60

14

2.4.3.2 Pastry goods

Most of the practical trials in the pastry goods sector were carried out with biscuits, since

biscuits usually have a tong shelf-life. Table 2.4 shows a biscuit recipe with 70% wheat flour

and 30% soy flour. The remaining ingredients are the same as in normal biscuit recipes

(Jongh, 1961).

Table 2.4 Biscuit recipe with 70% wheat flour

Component %

Wheat flour 70

Soy flour 30

Baking fat 20

Sugar 25

Syrup 4

Salt 1

Baking powder 2

CSL 1

2.4.4 Nutritional value of composite baked goods

Dough bread types made from composite flours have greater nutritional value than wheat

bread. Special nutritional studies were carried out parallel to the development of various

types of bread made from composite flours.

The trials conducted by Kim (1968) from TNO Wageningen, Netherlands, may be considered

a typical example. They compared

• conventional white Dutch bread (100% wheat flour)

• cassava (80%) - soy (20%) bread, and

• cassava (80% - peanut (20%) bread in feed trials with rats.

Among other things they recorded the net protein utilization (NPU), digestibility (D) and the

protein efficiency ratio (PER). From the NPU and D, the biological value (BV) was

calculated. Table 2.5 shows the most important results. The NPU and D values of the

15

cassava-peanut bread correlated well with the normal white Dutch bread. The cassava-soy

bread was superior to the other two bread types due to the better protein quality of the

soybean as compared to peanuts and wheat. The PER value was also highest for the cassava-

soy bread; as a result, the rats fed with this bread were the heaviest. This leads to the

conclusion that the protein quality of bread made from composite flours is superior to that of

conventional Dutch white bread. The best values were achieved by the cassava-soy bread.

Table 2.5 Nutritional evaluation of various bread types made from wheat and composite flour

Where,

a wet basis

b net protein utilization

c digestibility

d biological value

e protein efficiency ratio

2.4.5 Treatment of composite flours

Abdel-Kader (2000) reported that when bakery products are made from composite flour, their

overall quality (odor and flavor, chewing properties, appearance, and shelf-life) should be as

similar as possible to those of products made from wheat. To achieve this, the wheat flour

contained in the composite flour must be suitably treated. The familiar flour improvers’

potassium bromate and ascorbic acid have proved very satisfactory for this purpose. The

amount added must be adjusted to the quality of the wheat flour. As a rule it is between 20

and 50 ppm.

Product protein NPUa Db BVc PERd e

White Dutch bread 10.2 48 94 51 2.50

Cassava / soy

10.3 60 92 65 1.26

Cassava / peanut 12.4 49 91 54 0.86

16

Modem enzyme preparations are also capable of compensating for the loss in volume

resulting from the composite flour as compared to pure wheat flour. Hemicelluloses and also

lipases can be used as well as amylases.

The technical problem for the baker is usually poor dough formation in the mixing and

kneading process. Pre-gelatinized starches and certain emulsifiers have proved useful here.

Numerous tests have been carried out on the use of emulsifiers (Khalil et.al., 2000).

Especially in the case of mixtures containing only a small proportion of wheat flour, glycerol

monostearate (1%, flour basis) as an emulsion (GMS : water = 9.1) has proved useful when

added during preparation of the dough. Table 2.6 gives an overview of the improvements that

are possible in respect of volume when certain emulsifiers and pre-gelatinized starches are

used in bread production. Oxidative flour treatment with 25 ppm ascorbic acid was also used

in these tests.Apart from oxidative treatment with potassium bromate and ascorbic add, it is

also important to use sufficient amounts of water ¬binding substances such as pre gelatinized

products and to ensure that the wheat flour has optimum baking properties in accordance with

its percentage of the mixture. In addition to monoglycerides, other emulsifiers CSL and SSL

have proved very satisfactory.

Table 2.6 Influence of flour treatment and gelatinized starch on loaf volume of

composite flour from cassava starch and wheat flour (50/50 %)

Additive Dosage (%) Volume (ml/kg flour)

No additive - 2,600

Gelatinized maize starch 10 3,700

Soy lecithin 4 3,900

Glyceryl monostearate 1 4,300

Calcium stearoyllactylate 0.8 4,200

17

2.5 Major cake ingredients

Bakery Science Corporation, 2007 cited the following major cake ingredients.

2.5.1 Cake flour

Flour is the primary structure builder and is used to bind all of the other ingredients together

during the cake making process. Short extraction, Chlorinated Soft wheat flour is best suited

for use in high ratio layer cakes. Soft wheat flour is generally low in water absorption and

does not require harsh mixing or a long mix time.

A short patent flour of low ash and protein is ideal. In the milling process, the "extraction" is

defined as the portion of the wheat berry as a whole which is milled into actual flour. A

normal extraction is approximately 72 percent of the wheat berry. This flour which has been

extracted is gradually separated into streams consisting of one of the following categories:

Extra short or fancy patent flour, short, medium, long, and very long patent flour. The shorter

the patent, the more refined (has a lower degree of separation) the flour will be.

The following specifications are recommended for typical cake flour. The protein content

should be 8 ± 0.5% with a moisture content of 13 ± 0.5%, an ash level of .35± 0.05% and a

particle size of 10±0.5 microns. The flour should be well bleached with chlorine bleach, (not

benzyl peroxide) to a pH level of 4.4 - 4.8. Chlorination of flour provides 2 great benefits.

First is bleaching, which gives a better crumb color but second and more importantly it

lowers the gelatinization temperature of the starch within the flour. This makes it possible for

the cake to set faster and therefore reduces the loss of leavening during baking. Bleaching

also gives the flour the ability to carry more sugar and shortening as well as water. Bleached

flour must be used in high ratio cakes where the sugar is higher than the flour level.

2.5.2 Sugar

Sugar is mainly used as a tenderizer in cakes because of the softening effect it has on the

protein in the flour (gluten.). Sugar is also used for sweetness, moisture retention, lubrication

of other ingredients, and crust color. Increasing sugar will raise the gelatinization temperature

of the starches in the flour and thus will increase expansion time. Granulated sugar will have

a cutting action during mixing and will help incorporate air into the batter. Sugar is also

hygroscopic and will assist with increasing shelf life.

18

Other types of sugars used in the bakery include dextrose and brown sugar. Also syrups such

as invert sugar, corn syrup, molasses, honey or refiner's syrups are used either for the

particular flavor they impart or as a moisture retaining agents. When using these sweetener

varieties you must be aware that some do not have the same sweetness as granulated sugar

(sucrose) and do contain various levels of water. Sugars of any kind when used in cakes tend

to soften the batter and make it thinner. Fine granulated sugar or special baker's sugar gives

the best results in cake work.

2.5.3 Shortening

The primary function of shortening in cakes is to incorporate air in the finished cake batter.

Any ingredient that incorporates air acts as a tenderizer; therefore shortening is a tenderizing

agent. Shortening is also used in lubrication of other ingredients which allows the cake to rise

more freely and increases the shelf life by helping to retain moisture in the finished cake. The

types of shortenings used today are as follows: All-purpose shortening- This is a non-

emulsified hydrogenated shortening. This type of shortening can be used successfully in hi-

ratio cakes with the addition of emulsifiers (normally 2- 6% of the shortening weight). Cake

shortening or cake and Icing Shortening: This is an all-purpose hydrogenated shortening in

which the manufacturer has added one, two or a combination of emulsifiers. These

emulsifiers include but are not limited to mono & triglycerides, polysorbate 60, Propylene

Glycol monoesters, sodium Sterol Lactate and lecithin. The emulsifiers, which are blended

into the shortening, help to form an emulsion, especially at lower temperatures. This allows

the baker to add more water to the cakes and in this way improves the eating qualities of the

finished cake by retaining more moisture. Other types of shortening may include fluid

shortenings and butter or margarine.

2.5.4 Eggs

One of the main functions of eggs is to build structure (whites and whole eggs). They are

used as a tenderizer (yolks - contain lecithin - an emulsifier). They are also used for color,

nutrition, and flavor and help to retain moisture in the finished cake. The egg level of a layer

cake is usually 10% higher than the shortening level. Dry eggs are more convenient but liquid

eggs have more strength function.

19

2.6 Cake making functions

Bakery Science Corporation, 2007 mentioned the following cake making functions.

2.6.1 Mixing

Mixing of a cake batter serves the purpose of hydrating the ingredients, dispersing the

ingredients and aerating the batter.

During mixing, water-containing ingredients (e.g., water, liquid eggs, and liquid milk) are

combined with the dry ingredients of the formula. In this process, the water is distributed

such that it can serve to unlock the functionality of various ingredients. For example, water

dissolves the chemical leaveners, enabling them to contribute towards the leavening action in

the cake batter. Starches in the flour are also hydrated such that, during baking, their

gelatinization can serve as an integral part of the structure formation of the cake. In addition,

hydration of the various ingredients leads to fluidity (viscosity) of the batter that is directly

involved in the development of a high quality cake.

2.6.2 Evenly dispersion of ingredients

During the mixing process, the various ingredients of a cake formula are combined and

dispersed to form a homogeneous mixture that is free of lumps. A major factor in forming

this type of mixture for cake batters is the combining of the fat and water components of the

formula. These two constituents are normally incapable of being combined. Emulsifiers make

it possible to blend the fat and water components. As a result, mixing of a cake batter results

in the formation of an oil-in-water emulsion in which the various ingredients are evenly

dispersed. In certain instances, such as addition of too much liquid or adding it too rapidly, a

loss of the oil-in-water emulsion can occur. This, then, produces a “curdled” batter, in which

lumps of fat become separated from the aqueous portion. Because the batter is no longer

uniformly mixed, the quality of the finished cake is adversely affected. Characteristics

observed in a cake produced from curdled batter include low volume, coarse crumb, sugary

top crust, and tender structure.

20

2.6.3 Properly aeration of batter

Aerating of batter cakes is incorporation of air into the batter during mixing. Expansion of

this air during the baking process leads to an increase in the volume of the cake. The air cells

incorporated during mixing serve as nuclei to collect and hold the carbon dioxide (CO2) gas

released by the action of the chemical leaveners. The number and size of air bubbles

incorporated during mixing directly affect the volume and grain of the finished cake. Low

and medium speed mixing in open bowl mixers is most efficient at producing air cells, as

higher speeds result in the formation of fewer cells, and those that are produced tend to be

coarser and more irregular. Large air cells have greater buoyancy than smaller cells, and thus,

have an increased chance of loss due to rising to the surface of the batter and subsequent

departure. This can lead to low finished cake volumes and coarse grain. Thus, smaller

bubbles provide more nuclei for gas retention and thus make a larger cake with a finer grain.

Smaller bubbles or a finer grain also retain more moisture as the cake cools. A greater

number of air cells in a batter contribute to a more efficient utilization of chemical leaveners.

This results from the increased number of cells more effectively collecting and retaining the

CO2

produced by the leaveners. Subsequently, this leads to an improved finished cake

volume. Finally, evenness in the size of the air bubbles in a batter is an important factor.

Similarly sized, small air cells contribute towards improved grain characteristics in the baked

cake. Adherence to proper mixing techniques results in aeration of the batter in a manner

conducive to the development of these evenly sized cells.

2.7 Mixing methods

Mixing is basically accomplished in 4 steps: 1.) The wetting of ingredients. 2.) Incorporation

of air into the batter. 3.) A homogeneous dispersion of air becoming increasingly fine

throughout the batter. 4.) Elimination of possible large air pockets and still a finer break

down of the air cells. Please note that it is possible to produce a variety of differences in the

finished product by changing the formula and/or mixing methods by which the batter is

assembled. The two most common cake mixing methods used in the baking industry today

the multi-stage mixing and continuous mixing (Atkins, 1971).

21

2.7.1 Multi stage mixing

In these mixing method only partial additions of liquids is made to the dry ingredients. The

multistage mixing methods by Atkins (1971) are given in Table 2.7.

Table 2.7 Multistage mixing methods

All-purpose shortening 50 lbs. Add Ingredients to Bottom of Bowl

Mix 1 min. @ 35-40 RPM Granulated sugar 100 lbs.

Cake Flour 50 lbs.

Mix 30 sec. @ 90 RPM Mix 2 min. @ 100 Rpm

Water

Liquid Whole Eggs 30 lbs. Add at 35 RPM, Scrape. Mix 1 min. @ 40 RPM Mix 4 min. @90 Rpm Water 10 lbs.

Liquid Whole Eggs 20 lbs. Add at @35 RPM

Scrape down sides of Bowl Water 25 lbs.

Flavors 2.5 lbs.

Vegetable Oil 5 lbs. Mix 4 min. @35 RPM

2.7.2 Continuous mixing

The basic equipment required for continuous cake batter mixing consists of a pre- mixer, a

holding tank and the continuous mixer.

The preparation of the slurry is a relatively simple process and is usually accomplished in an

automatic mixer into which all the wet and dry ingredients are automatically metered,

followed by the manual addition of the shortening and minor ingredients.

22

The actual mixing is accomplished in a mixing head which has only one moving part called a

"rotor". This rotor revolved at raring speeds between places (or stators) carrying a very large

number of rods and the emulsifying action in this head is accomplished by "liquid sheer".

Depending on the size of the mixing head, there is relatively a small amount of batter passing

into and through at any time. If the output was 3500 -4000 pounds of batter per hour, the

material would remain in the head only @ 3 seconds. The density (specific gravity) is

controlled by a small valve on a "flowrator" which is a meter used to measure the volume of

air being pumped into the mix. Using this system the batch size and production speed can be

greatly increased. This is due to the fact the mixing time in the premix to the depositor is very

short, (@1 - 3 minutes in the premix and only seconds in the actual mixing head) also there is

little or no aeration of the batter in the pre-mix stage (the specific gravity staling at @ 1.100),

so there is no need to make an allowance for any rise of the batter in the bowl.

2.8 Factors involved in cake processing

According to Bakery Science Corporation, 2007 the following factors are involved in cake

processing.

2.8.1 Batter temperature

The temperature of finished cake batter is very important this is due to the batter

temperature's affect to the viscosity which in turn affects both the stability of the batter and

its ability to incorporate air. The Table 2.8 listed below can be used as a guide line for

temperatures and specific gravity in various cake batters.

Table 2.8 Temperatures and specific gravity in various cake batters

CAKE BATTER TEMPERATURE SPECIFIC GRAVITY

yellow layer 68-72 0.70-0.80

White layer 68-72 0.70-0.80

devils food 68-72 0.70-0.80

Pound Cake 68-72 0.80-0.90

23

If the cake batter is too cold, it will take a longer amount of time for the vapor pressure to be

developed (The vapor pressure is what allows the cake to rise). This gives the cake time to

crust over and set on top before expansion really takes place. This will produce cracking and

result in a poor looking top on finished cake. The optimum temperature should be between 68

– 720

F for a finished cake batter.

2.8.2 Specific gravity

Specific gravity is recorded as the degree of aeration in the batter and is directly related to the

final cake volume. This also affects the symmetry, texture and grain. Whenever changes are

made in ingredients, mixing operation or equipment design the aeration of the batter will

most likely vary. Specific gravity is the ratio between the weight of a given volume of any

substance (i.e. the cake batter) and the weight of the same volume. You can use virtually any

container available in the bakery following the formula below to determine the specific

gravity of any batter.

Specific gravity =

2.8.3 Scaling

Scaling for various weights of cakes is shown below in Table 2.9.

Table 2.9 Scaling for various weights of cakes

Scaling Weight Pan Size

(inches)

Baking

Temperature

(F)

Bake Time

(Minutes)

Expected Bake

Loss

7-8 oz. 6 inch round 390-410 13-16 16%

9-11 oz. 7 inch round 370-390 16-19 15%

12-14 oz. 8 inch round 360-380 21-23 13%

14-16 oz. 9 inch round 350-370 25-29 12%

24

2.8.4 Floor time

Once the cake batter has been mixed it should be deposited into the cake pans and conveyed

into the oven with a "minimum" loss of time. This is because once the batter has been mixed

the leavening agents have gone into solution and begun to interact. In more fluid batters such

as cake batters, the gas tends to rise towards the surface with the small bubbles coalescing in

the process into larger cells. There is an inevitable escape of leavening gas from the batter

which is held on the floor in bowls or an open hopper as well as a coarsening of the cell

structure over extended periods of time.

2.8.5 Baking

The optimum baking conditions for cakes are determined by such factors and the richness or

leanness of the formula, the flow and density of the batter, pan size etc. Cakes which are

larger in size and / or are richer in formulation generally are baked at lower oven

temperatures for longer periods of time when compared with leaner formulations and/or

smaller size cakes. Here is a list of representative cake baking times and temperatures for a

conventional oven. The ranges of bake times and temperatures for each variety provide the

needed margins for adjustment in both factors to conform to the particular scaling weight of

the product. In all instances the maximum internal temperature of the finished cakes is 208-

2100

Table 2.10 Typical bake time and temperature for cake variety

F. The details data are show in Table 2.10 below.

Cake Variety Bake Time Temperature

Layer Cake 20-25 min. 365-375

Loaf Cake 35-50 min. 350-360

Pound Cake 50-65 min. 325-365

Sponge Cake 10-20 min. 390-420

Crème Cake 30-45 min. 350-375

Cup Cakes 13-22 min. 375-400

25

2.9 Effects of changing ingredients level on cake batter

The effects of changing water levels in sponge cake better with a continuous mixer-aerator

were reported by Cauvain and Cyster (1996). They varied the level of added water but kept

all of the other ingredients constant so that their water levels ranged from 28 to 34% of the

batter weight. Batter viscosity fell as the water level increased, which affected the ability of

the batter to pass through the mixer head and batter throughput rates for a constant pump

speed. The more viscous batters experienced a greater heat rise during mixing. As the water

content of the batter increased there was a linear increase in final cake moisture content and a

decrease in the sponge cake specific volume.

Cauvain and Screen (1990) studied the effect of changing ingredients levels with a high ratio

unit cake formulation and also found that cake specific volume decreased as the water level

increased. Of the five ingredients they tested, the effect per unit of water on cake volume was

much larger than the other four ingredients they tested (sugar, skimmed milk powder, fat and

whole egg).

26

Chapter 3

MATERIALS AND METHODS

The experiment was conducted in the laboratory of the Department of Food Technology and

Rural Industries, Bangladesh Agricultural University (BAU), Mymensingh, Bangladesh.

3.1 Materials

Wheat flour, good quality cardinal potatoes, and fresh carrots used in the study were procured

from local market. Good quality commercial wheat flour (Brand: Teer Maida) was collected

from local market and potato and carrot flours were prepared in the laboratory. All other

necessary ingredient and chemicals were used from laboratory stocks.

3.2 Methods

3.2.1 Procedures for preparation of potato flour

The selected potatoes were cleaned and washed using potable water and peeled. Then the

potatoes were cut into 3 mm thick slices by knives. Then the slices were blanched for 1

minute in boiling water and dipped into 0.1 % KMS solution for 5 minutes. Cabinet dryer

was used for dehydration of these potato slices. The slices were then dried for about 16 hours

at 650

C. The potato flour was prepared by grinding the dried potato slices in a flour mill and

the flour was kept in polyethylene bags for cake manufacture. The schematic diagram for

preparation of potato flour is shown in figure 3.1.

27

Figure 3.1 Schematic diagrams for preparation of potato flour/carrot flour

Washing with potable water

Peeling

Slicing (in 20x15x3 mm)

Blanching

Dip into KMS solutions

Drying

Grinding

Potato flour

Fresh potatoes/carrots

28

3.2.2 Procedure for preparation of carrot flour

Fresh carrots were selected for preparation of carrot flour. The carrots were first thoroughly

washed in clean tap water to remove adhering gum, soil and other unwanted materials. The

cleaned carrots were then peeled by knives. The peeled carrots were then cut into 10 cm

longitudinal sections and then cut into 3 mm thick slices by knives. Then the slices were

pretreated by blanching for 1 minute in boiling water and dipped into 0.1% KMS solution for

5 minutes. Then the slices were dried for about 16 hours at 65°C. The carrots flour was

prepared by grinding the dried carrot slices in a flour mill and the flour was kept in

polyethylene bags for cake manufacture. The schematic diagram for preparation of carrot

flour is shown in figure 3.1.

3.2.3 Chemical analysis of fresh potato, carrot and wheat flour

The potato, carrot and wheat flour were analyzed for moisture content, protein, ash, crude fat,

crude fiber and total carbohydrate. All the determinations were done in triplicate and the

results were expressed as the average value.

3.2.3.1 Moisture

Moisture content was determined adopting AOAC (2005) method. About 5 g was taken in a

pre-weight crucible (provided with cover) which was previously heated to 1300C. The sample

was dried for 24 hr in an air oven maintained at temperature 1050

C. The crucible was covered

while still in oven then transferred to desiccators and weighed immediately after reaching at

room temperature. The loss of weight from sample was determined and the percent of

moisture was calculated as follows:

% Moisture content = × 100

29

3.2.3.2 Protein

Protein content was determined using AOAC (2005) method. The method was as follows:

Reagent required: Sulfuric acid (nitrogen free); digestion mixture-100g, sodium sulphate,

20g copper sulphate and 5 g selenium di-oxide powder, well mixed in a mortar and kept in a

dry place; 40% sodium hydroxide solution, approximately 0.1N hydrochloric acid; Mixed

indicator solution- Bromocresol green = 0.1 g and Methyl red = 0.02 g, dissolved in ethyl

alcohol (100 ml); Boric acid solution-a 1.0% solution in water.

Procedures: A 5g digestion mixture was weighed accurately and transferred into a dry

300ml Kjeldahl flask. A suitable quantity of the sample (1 g for each) was transferred into the

flask. 20ml of sulphuric acid was added, heated continuously until frothing ceased and then

simmered briskly. The solution became clear in 15-20 min, continued heating for 45 min.

After cooling, 1000ml water was added, and transferred quantitatively to a 1-litre round-

bottom flask; the final volume was about 500ml. Added gently sown the side enough sodium

hydroxide solution to form a precipitate of cupric hydroxide and immediately connected the

flask to steam-trap and condenser. Then 50ml of boric acid solution, 50ml of boric acid

solution, 50ml distilled water and 5 drops of indicator solution were added to a 500ml conical

receiving flask. Positioning the condenser distillation was carried out for 40 to 45 minutes or

until about 250ml of distillate was obtained. The contents of the receiving flask were titrated

with 0.1 N hydrochloric acid, the end point was marked by a brown color. A reagent blank

was also determined and deducted from the titration.

1ml of 0.1N hydrochloric acid is equivalent to 1mg of nitrogen. A protein conversion factor

of 5.7 was used to calculate the percent protein from nitrogen determination. Percentage of

nitrogen and protein calculated by the following equations:

% N2 = × 100

Where,

TS

Tb = Titer volume of the Blank (ml)

= Titer volume of the sample (ml)

Meq. Of N2

% Protein = Nitrogen × 6.2

= 0.014

30

3.2.3.3 Ash AOAC (2005) method was used to determine the total ash content.

Procedure: 2g sample was weighed into clean, dry porcelain ashing dish which was

previously heated to remove moisture. The sample was then ignited with a gas burner until

white smoking stopped. The sample was then placed in a muffle furnace at 5500

% Ash =

C and ignited

until light gray ash resulted (or to constant weight). The sample was then cooled in

desiccators and weighed. The ash content was calculated by following expression:

× 100

3.2.3.4 Fat

AOAC (2005) method using soxhlet apparatus was used to determine crude fat content of the

samples.

Procedure: The dried sample was transferred to a thimble and plugged the top of the thimble

with a wood of fat free cotton. The thimble was dropped into the fat extraction tube attached

to a Soxhlet apparatus. Approximately 75 ml or more of anhydrous petroleum ether was

poured through the sample in the tube into the flask. Top of the fat extraction tube was

attached to the condenser. The sample was extracted for 16 hrs or longer on a water bath at

70-800

C.

At the end of the extraction period, the thimble from the apparatus was removed and distilled

of the petroleum ether by allowing it or collected in soxhlet tube. The petroleum ether was

poured off when its volume, was nearly full. When the petroleum ether had reached small

volume, it was purer into a small, dry (previously weighed) beaker through a small funnel

containing plug cotton. The flask was rinsed and filtered thoroughly using petroleum ether.

The petroleum ether was evaporated on steam bath at low temperature and was then dried at

1000

C for 1 hr, cooled and weighed. The deference in the weight gave the ether soluble

materials present in the sample. The per cent of crude fat was expressed as follows:

% Crude fat = × 100

31

3.2.3.5 Crude fiber

Crude fiber was determined according to AOAC (2005) method. The method was as follows:

Reagent required: 0.255N sulphuric acid solution (i.e. 1.25 g H2SO4

Procedures: 2 g sample remaining after crude fat determination was taken and transferred to

the digestion flask with approximately 0.5 g asbestos. Added 200 ml of boiling sulphuric acid

solution and immediately was connected the digestion flask with lei big condenser and was

boiled briskly for 30 min. During digestion care was taken to keep material remaining on the

sides of the digestion flask without contact with completed the boiling, the flask was removed

and filtrated through linen in a fluted funnel and washed with boiling water until the

washings are no longer acid. Heated sodium hydroxide solution to boiling under reflux

condenser and washed the residue from acid digestion back into the flask with 200 ml of

boiling sodium hydroxide solution and connected the flask with reflux condenser and boiled

for exactly 30 min. After 30 min. of boiling the flask was removed and immediately filtered

through filtering cloth in a fluted funnel washed with water and potassium sulphate solution.

Returned the residue to the digestion flask thoroughly washed all residues from cloth with hot

water. It was filtered into the Gooch crucible prepared with thin but a packed layer of ignited

asbestos.

/100 ml water); 0.313N

sodium hydroxide solution (i.e. 1.25 g NaOH/100 ml water); 10.0% Potassium sulphate

solution; Asbestos-Gooch grade.

After washing of the residue in the Gooch crucible with boiling water, washing was repeated

with approximately 15 ml of alcohol. The crucible with the contents was dried at 1100C to

constant weight and then cooled in a desiccators and weighed. The content of the crucible

was ignited in an electric muffle furnace at dull red heat (5500

C) until carbonaceous is

destroyed (approximately 20 minutes). Cooled in a desiccator's and again was weighed. The

loss in weight represents crude fiber.

% Crude fiber = × 100

32

3.2.3.6 Total carbohydrate

Total carbohydrate content of the sample were determined as total carbohydrate by

difference, that is by subtracting the measured protein, fat, ash and moisture from 100

(Pearson, 1970).

3.2.4 Product development

3.2.4.1 Formulation of cake by incorporating composite flour

The basic formulation for plain cake (multi-stage mixing) and composite flour cakes are

outlined in Table 3.1 (Atkins, 1971; Bugusu et al. 2001; Anon, 2000). The replacements of

wheat flour in the formulations were made with different levels of composite flour.

Table 3.1 Basic formulation for preparation of plain cake and composite flour cakes (on 100 g flour basis)

Ingredients

Samples

Basic formulation

Composite flour incorporated formulation

S1 S(Control) S2 S3 4

Wheat flour (g) 100 70 70 70

Potato flour(g) 0.0 05 15 25

Carrot flour (g) 0.0 25 15 05

Sugar (g) 90 90 90 90

Oil (g) 90 90 90 90

Baking powder(g) 04 04 04 04

Powder milk (g) 25 25 25 25

Salt (g) 02 02 02 02

Egg (No.s) 02 02 02 02

Water (ml) 50 50 50 50

33

3.2.4.2 Procedure for preparation of composite cake

Cakes were prepared by replacing wheat flour with different levels of composite flour in the

basic formulation of cake (Table 3.1) as per the methods of Rajchel et al. (1975). The wheat

flour, potato flour, carrot flour and other ingredients for each cake sample was weighed

accurately. The flours were mixed together according to the percentages shown in Table 3.1.

Then the sugar and shortening were mixed in a mixing machine for 20 minutes to produce a

cream. In later stages one egg and other ingredients and finally the mixed flour were added

and mixed well using a mixer at low speed (145 rpm) for 10 minutes to ensure even

distribution of the components. The bowl was scrapped and stirred for an additional two

minutes at medium speed (250 rpm). Then another egg was added and the mixture was stirred

at low speed for two minutes. After the bowl was scrapped, the mixture was stirred an

additional two minutes at medium speed. Then a portion of batter was scaled into pre-greased

cake pan. All cakes were baked in air oven for 45 minutes at 1700

C. The schematic diagram

for preparation of composite cake is shown in figure 3.2.

34

Figure 3.2 Schematic diagrams for preparation of composite cake

Mixing of flours well

Mixing of salt, baking powder and powder milk

Beating egg

Adding prepared all one by one slowly

Continue mixing 2 minutes after last addition

Adding the rest of eggs

Pouring into cake pans

Baking

Cooling

Weighing of wheat, potato and carrot flour

35

3.2.5 Chemical analysis of cakes containing composite flour

The cake samples S1 (control cake), S2 (70% wheat flour, 5% potato flour, 25% carrot flour),

S3 (70% wheat flour, 15% potato flour, 15% carrot flour) and S4

(70% wheat flour, 25%

potato flour, 5% carrot flour) were analyzed for moisture content, protein, ash, crude fat and

crude fiber as per the methods of AOAC (2005) and total Carbohydrate content (Pearson,

1970).

3.2.6 Evaluation of cakes by objective analysis

Cake volume was initially used as an important parameter of cake quality. The cake volume

was determined by seed displacement method (Ott, 1987). Moisture content was determined

according to the methods outlined in AOAC (2005). The weights and specific volumes of

baked cakes were also measured.

3.2.7 Evaluation of effect of various levels of composite flour on cake quality

The composite flour cakes were prepared by incorporation of different levels of composite

flour in the formulation by the procedures described in Section 3.2.5.2. Effects on volume,

weight, moisture content and specific volume were evaluated by the procedure described in

Section 3.2.7.

3.2.8 Subjective (sensory) evaluation of cakes

The symmetry and the characteristics of crust and crumb of the cakes supplemented with

wheat, potato and carrot flour samples were evaluated and recorded. Cakes were evaluated

organoleptically for color, flavor, texture and overall acceptability. A 1-9 point hedonic rating

test (Appendix I-VIII) was also performed to assess the degree of acceptability of cakes

containing different levels of potato and carrot flour. One slice from each lot of cake was

presented to 10 panelists as randomly coded samples. The taste panelists were asked to rate

the sample for color, flavor, texture and overall acceptability on a 1-9 point scale where, 1 =

dislike extremely, 2 = dislike very much, 3 = dislike moderately, 4 = dislike slightly, 5 =

neither like nor dislike, 6 = like slightly, 7 = like moderately, 8 = like very much, 9 = like

extremely. The results were evaluated by Analysis of variance and Duncan’s New Multiple

Range Test procedures of the Statistical Analysis system (SAS, 1985).

36

3.2.9 Observation on storage stability of composite cake

The storage stability of different composite cakes was observed at various storage conditions

in terms of moisture gain. Each 10 g sample was packed with single layer high density

polythene and stored at room temperature (300C) and refrigeration temperature (50C). The

moisture uptake by composite cakes at every day was determined gravimetrically and

observed moisture uptake conditions.

37

Chapter 4

RESULTS AND DISCUSSION

4.1 Proximate compositions of wheat, potato and carrot flours

The results of the proximate composition of wheat, potato and carrot flour are presented in

Table 4.1.

Wheat flour contained moisture 12.64% and 14.46%, protein 11.37% and 13.01%, fat 0.83%

and 0.95%, ash 0.67% and 0.77%, crude fiber 0.39% and 0.45% and total carbohydrates

74.49% and 85.26% by wet weight and dry weight basis respectively. The composition of

wheat flour under study was more or less similar to those reported by Samuel (1960). He

reported the composition of wheat flour as follows moisture 14%, protein 11.25%, fat 1.0%,

ash 0.5%, crude fiber 0.4% and total carbohydrates 72%.

The potato flour contained moisture 14.63% and 17.13%, protein 5.65% and 6.62%, fat

0.97% and 1.12%, ash 2.63% 3.1%, crude fiber 4.35% and 5.09% and total carbohydrates

76.12% and 89.16% by wet weight wet basis and dry wet basis respectively. The results were

congruent to that reported by Schwimmer and Burr (1967) who showed that potato flour

contained moisture 11.20% (wb), protein 5.50%, fat 0.85%, ash 2.40%, crude fiber 4.30%

and total carbohydrates 75.75%.

Carrot flour contained moisture 5.37% and 5.67%, protein 6.89% and 7.28%, fat 1.12% and

1.18%, ash 5.33% and 5.63%, crude fiber 2.24% and 2.36% and total carbohydrates 81.29%

and 85.91% by wet weight basis and dry weight basis respectively. The results were similar

with the findings reported by USDA (1997) which reported that carrot flour contained

moisture 3%, protein 7%, fat 1.40%, ash 5.50%, crude fiber 2.25% and total carbohydrates

80.85%.

The small variations observed in the comparing data may be due to the varietal differences,

and quality, agro-ecological condition, fertilizer use, extent of drying, storage conditions,

methods of analysis etc.

By dry weight basis it was observed that wheat flour contained the highest amount of protein

than that of potato and carrot flour, potato flour contained the highest amount of moisture,

38

crude fiber and carbohydrates than that of wheat and carrot flour, and carrot flour contained

the highest amount of fat and ash than that of wheat and potato flour.

Table 4.1 Approximate composition of wheat, potato, and carrot flour

Components Wheat flour Potato flour Carrot flour

Moisture (%) 12.64 (14.46) 14.63 (17.13) 5.37 (5.67)

Protein (%) 11.37 (13.01) 5.65 (6.62) 6.89 (7.28)

Fat (%) 0.83 (0.95) 0.97 (1.12) 1.12 (1.18)

Ash (%) 0.67 (0.77) 2.63 (3.1) 5.33 (5.63)

Crude fiber (%) 0.39 (0.45) 4.35 (5.09) 2.24 (2.36)

Total carbohydrates

74.49 (85.26) 76.12 (89.16) 81.29 (85.91)

Data in bracket are in dry weight basis

4.2 The effect of composite flour on cake properties

Cakes prepared by incorporating 5%, 15% and 25% potato flour and 25%, 15% and 5%

carrot flour with 70% wheat flour respectively were evaluated for physical properties and

external and internal characteristics. The samples are designed according to S1 = Control

sample (with only wheat flour); S2 = Containing 70% wheat flour, 5% potato flour, 25%

carrot flour; S3 = Containing 70% wheat flour, 15% potato flour, 15% carrot flour; S4

=

Containing 70% wheat flour, 25% potato flour, 5% carrot flour.

4.2.1 Physical properties of cake

4.2.1.1 Cake volume

The cakes were prepared by incorporation of different level of composite flour in formulation

of plain cakes. The loaf volume is the most important individual quality parameter used for

evaluation of cake and bread. It is a quantitative measurement and correlates well with dough

handling properties, crumb, texture, freshness and technological versatility (Pomeranz, 1980).

The volumes of cakes prepared with different level of composite flour are presented in figure

4.2 (data shown in Table 4.2). The cakes (245-263cc.) with different level of composite flour

had higher volumes than that of control cake (215cc.) prepared from wheat flour only. It was

also observed that the volumes among the composite cake samples (from S2 to S4) gradually

decreased with increasing the level of potato flour and decreasing level of carrot flour in

39

composite flour of dough. This might be due to the fact that potato flour contains higher

percentage of fiber than that of wheat and carrot and carrot flour contains higher percentage

of fat than that of wheat and potato (Table 4.1).

A significant impact of fiber is to reduce dough gas retention and of fat is to increase dough

gas retention (Williams and Pullen, 1998). Thus the cake volume decreased with fiber

percentage increasing (from S2 to S4) and the cake volume increased with fat percentage

increasing (from S4 to S2

).

Figure 4.1 Physical appearances of control cake and composite cakes

Where,

S1

S

= Control sample (with only wheat flour)

2

S

= Containing 70% wheat flour, 5% potato flour, 25% carrot flour

3

S

= Containing 70% wheat flour, 15% potato flour, 15% carrot flour

4 = Containing 70% wheat flour, 25% potato flour, 5% carrot flour

S2 S3 S4 S1

40

Figure 4.2 Effect of potato-carrot mixed flour on composite cake volume

41

4.2.1.2 Weights of cake

The weights of cakes prepared with different level of composite flour in the formulation of

plain cake are presented in Table 4.2. The cakes (173.6-184.2g) with different level of

composite flour reached higher weights than the control cake (165.0g) prepared from wheat

flour only. It was also observed that the weights of the composite cake samples (from S2 to

S4

) gradually increased with increasing the level of potato flour in composite flour of dough.

This might be due to the fact that potato flour contains higher percentage of fiber than that of

wheat and carrot (Table 4.1). The fiber holds the water which contributes to the higher weight

of the composite flour cake (Cauvain, 1996).

4.2.1.3 Specific volumes of cakes

The specific volumes of cakes prepared with different level of composite flour in the

formulation of plain cake are presented in Table 4.2.

The cakes with different level of composite flour gained higher specific volumes (1.33-

1.51cc/g.) than that of control cake (1.30cc/g) prepared from wheat flour only. The specific

volumes of control cake (1.30cc/g) and the composite cake sample S4 (1.33cc/g) were nearly

equal. It was also observed that the specific volumes among the composite cake samples

(from S2 to S4) gradually decreased with increasing the level of potato flour and decreasing

level of carrot flour in composite flour of dough. The fiber content increased as well as the fat

content decreased from sample S2 to S4

. The weight increased while volume decreased of the

composite cakes (Williams and Pullen, 1998). The specific volume (cc/g) gradually

decreased among the composite cakes.

42

Figure 4.3 Effect of potato- carrot mixed flour on weight of composite cake

43

1

1.05

1.1

1.15

1.2

1.25

1.3

1.35

1.4

1.45

1.5

1.55

0 0.2 1 5

Spec

ific

volu

me

(cc/

g)

Potato-carrot mixing ratio in composite dough

: Control (with only wheat flour) : S-2 (70% wheat flour, 5% potato flour and 25% carrot flour) : S-3 (70% wheat flour, 15% potatoflour and 15% carrot flour) : S-4 (70% wheat flour, 25% potato flour and 5% carrot flour)

0

0.2

1

5

Figure 4.4 Effect of potato-carrot mixed flour on specific volume of composite cake

44

4.2.1.4 Moisture contents of cakes

The moisture contents of cakes prepared with different level of composite flour in the

formulation of plain cake are presented in Table 4.2. The cakes with different level of

composite flour obtained higher moisture contents (22.12-26.93 %) than the cake prepared

from wheat flour only (21.31%). It was also observed that the moisture content of the

composite cake samples (from S2 to S4

Table 4.2 Effects of composite flour level on the volume, weight and moisture content of

cake

) gradually increases with increasing level of potato

flour in composite flour of dough. This might be due to the fact that potato flour contains

higher percentage of fiber than that of wheat and carrot. The fiber may hold the water which

may contribute to the higher moisture content of the composite flour cake (Cauvain and

Young, 2006).

Where,

S1

S

= Control sample (with only wheat flour)

2

S

= Containing 70% wheat flour, 5% potato flour, 25% carrot flour

3

S

= Containing 70% wheat flour, 15% potato flour, 15% carrot flour

4

= Containing 70% wheat flour, 25% potato flour, 5% carrot flour

Sample

Volume

(cc)

Volume

(% of

control

cake)

Weight

(g)

Weight

(% of

control

cake)

Specific

volume

(cc/g)

Moisture

content

(%)

S 215 1 100 165.0 100 1.30 21.31

S 263 2 122 173.6 108 1.51 22.12

S 250 3 116 178.8 111 1.39 24.32

S 245 4 113 184.2 115 1.33 26.93

45

10

12

14

16

18

20

22

24

26

28

30

0 0.2 1 5

Moi

stur

e co

nten

t (%

)

Potato-carrot mixing ratio in composite dough

: Control (With only wheat flour) : S-2 (70% wheat flour, 5% potato flour and 25% carrot flour) : S-3 (70% wheat flour, 15% potato flour and 15% carrot flour) : S-4 (70% wheat flour, 25% potato flour and 5% carrot flour)

0

0.2

1

5

Figure 4.5 Effect of potato-carrot mixed flour on moisture content of composite cake

46

4.2.2 Effects of composite flour on external and internal characteristics of cakes

The composite flour cakes were prepared by incorporation of different level of composite

flour were evaluated for their external and internal characteristics.

4.2.2.1 External characteristics of cake

4.2.2.1.1 Symmetry and bloom characteristics

Symmetry and bloom characteristics of cake containing different level of composite flour are

presented in Table 4.3. The term "symmetry" is self-explanatory. The most common faults

for while points were deducted: low edges, high edges, low centers, high centers and

unevenness. From Table 4.3, it is seen that the cake sample S4

The term bloom refers to luster or sheen. It describes the brilliance of the color. The sample

S

containing 70% wheat flour,

25% potato flour and 5% carrot flour gained better symmetry compared to other cakes.

4 (containing 70% wheat flour, 25% potato flour and 5% carrot flour) gained better bloom

than other samples with different substitution level. It was also observed from the view point

of symmetry and bloom characteristics less difference between samples S3 and S4

was

observed.

4.2.2.1.2 Crust characteristics

4.2.2.1.2.1 Color of crust

Color differences of cakes containing different level of composite flour relative to the control

are shown in Table 4.3. The crust color of the cake sample S2

(containing 70% wheat flour,

5% potato flour and 25% carrot flour) was deeper than those of control cake and other cake

samples. In general, the differences (deepness) in crust color between different cake samples

became larger as the potato flour level increased and carrot flour level decreased in dough.

4.2.2.1.2.2 Consistency of crust

This term applies to the condition of the crust and varies with the types of cakes. As shown in

Table 4.3, the tender crust was obtained in control sample. The cake sample S4 (containing

70% wheat flour, 25% potato flour and 5% carrot flour) gained medium tender crust. The

cake sample S2 and S3 had medium tough crust compared to both the control and the sample

47

S4. The overall crust characteristics of sample S4 seemed to be better than other samples (S2

and S3

4.2.2.2 Internal (crumb) characteristics of cakes

).

4.2.2.2.1 Color

Crumb colors of the cakes containing different level of potato and carrot flour are presented

in Table 4.3. Color evaluation was made with interior slices. Color differences were observed

between control cake and composite cakes. As shown in Table 4.3, the crumb color of the

control cake was brownish white, sample S2 was reddish yellow with 50% darker, sample S3

was reddish yellow with 25% darker and sample S4 was reddish yellow with 10% darker.

Sample S4

(containing 70% wheat flour, 25% potato flour and 5% carrot flour) gained better

crumb color than those obtained from cakes of different level of composite flour. This might

be due to the reddish color of the carrot flour. The decrease in the levels of carrot flour

substitution changed the crumb color of the composite cake samples from reddish yellow

with 50% darker to reddish yellow with 10% darker. A good live color regardless of kinds of

cake is always desirable (Bakery Science Corporation, 2007). The degree of deepness of

color will depend upon the formula and ingredients used.

4.2.2.2.2 Crumb texture

Crumb textures of the cakes containing various levels of composite flour are presented in

Table 4.3. Texture differences was observed between control cake and the sample S4

(Containing 25% potato and 5% carrot flour). The differences decreased with decreasing the

substitution levels of potato flour. The texture differences between the sample S2 (Containing

5% potato and 25% carrot flour) and the sample S3 (Containing 15% potato and 15% carrot

flour) cakes were less. A perfect texture should be free from lumps and harshness and have

smooth silky surfaces (Raffaela Pugliese, 2005) which were obtained in the sample S4. The

Summary of the different internal and external characteristics of composite flour cakes are

presented in Table 4.3.

48

Table 4.3 Effects of composite flour (composite) on symmetry, crust and crumb

Characteristics of cake

NOT TO BE PRINTED, alTER NaTIvE

PagE ThERE TO BE * aTTachED S1

S

= Control sample (with only wheat flour)

2

S

= Containing 70%wheat flour, 5% potato flour, 25% carrot flour

3

S

= Containing 70%wheat flour, 15% potato flour, 15% carrot flour

4

Cake

= Containing 70%wheat flour, 25% potato flour, 5% carrot flour

type

Symmetry Bloom Crust characteristics Crumb characteristics

Evenness Edges Centre Color Consistency Color Texture Flavor Grain

Lumps

and

hardness

Surface Close

or

airy

Shape

and size

S Medium

even 1 Medium Medium Slightly

dull

Brown Tender Brownish

white

Present

slightly

Light

smooth

Appetizing Airy Non-

uniform,

thin

walled

cells

S Medium

even 2 Low Low Shining Brownish

yellow,

darker 50%

Medium tough Reddish

yellow,

darker 50%

Present

slightly

Rough Vegetable

flavor

Less

airy

Less

uniform

S Even 3 Medium Medium Shining Brownish

yellow,

darker 25%

Medium tough Reddish

yellow,

darker 25%

Free Smooth Vegetable

flavor

Close Uniform

S Even 4 Medium Medium Luster Brownish

yellow,

darker 10%

Medium tender Reddish

yellow,

darker 10%

Free Smooth,

silky

Vegetable

flavor

Close Uniform

49

4.2.2.2.3 Crumb flavor The flavor differences of cake containing different level of composite flour relative to control

are provided in Table 4.3. The composite cake samples provided characteristic vegetable

flavor as compared to control cake (wheat flour only). The flavor of the cake samples S2 and

S3 were generally not so fresh than other samples. The acceptable flavor (i.e. fresh, sweet,

natural, appetizing) were found in cake sample S4 (containing 70% wheat flour, 25% potato

flour, 5% carrot flour). The sample S4

developed the attractable potato flavor.

4.2.2.2.4 Crumb grain

Crumb grain of cakes indicates to the shape, size and character of the cell wall structure of

crumb. The crumb grains of cakes containing different levels of composite flour substitution

are presented in Table 4.3.

Uniformity of size with thin walled cell is most desirable for crumb grain. Coarseness, thick

walled cells, uneven cell size and large holes are indicative of poor grain (Bakery Science

Corporation 2007). As shown in Table 4.3 the cake samples S2 (containing 5% potato flour

and 25% carrot flour) and S3 (Containing 15% potato and 15% carrot flour) gained coarser

grain and less uniform shape and size. The cake sample S4 (Containing 25% potato and 5%

carrot flour) secured better acceptable crumb grain. The crumb grain of S4

sample was

uniform and thin walled cells as compared to other cake samples.

4.3 The effect of composite flour on the composition of plain cake

In the present study four different samples of cakes S1 (with only wheat flour, termed as

control sample), S2 (containing 70% wheat flour, 5% potato flour and 25% carrot flour), S3

(containing 70% wheat flour, 15% potato flour and 15% carrot flour), and S4

(containing

70% wheat flour, 25% potato flour and 5% carrot flour) were processed and chemical

properties were measured to assess the quality. The cake samples were analyzed for moisture,

protein, fat, ash, crude fiber and total carbohydrates content.

50

4.3.1 Moisture content

The moisture contents of four different cake samples processed with different levels of

composite flour were shown in Table 4.4. Data in Table 4.4 showed that the moisture content

of control sample S1 (21.31%, wb and 27.08%, db) was lower than other samples. The

highest moisture content (26.93%, wb and 36.85%, db) was found in sample S4. It was seen

that the moisture content gradually increased from samples S2 to S4 with the increase of

substitution levels of potato flour in composite flour. This is due to the high concentration of

fibers which increased the water holding capacity of the composite flour cakes (Cauvain,

1996). Okorie and Onyeneke (2012) showed that the moisture content of the composite cake

(70% wheat flour and 30% sweet potato flour) was 26.72% which is similar to the sample S4

(26.93%) containing 70% wheat flour, 25% potato flour and 5% carrot flour.

4.3.2 Protein

The protein contents of four different cake samples processed with different levels of

composite flour were shown in Table 4.4. In present study it was observed that the protein

contents of all samples (7.93-7.97%, db) were lower than that of control sample (8.26%, db).

It was observed that protein content in composite cake samples increased (from S2 to S4) with

increased substitution level of potato flour and decreased substitution level of carrot flour in

composite dough (Table 4.4). Okorie and Onyeneke (2012) showed that the protein content

of the composite cake (70% wheat flour and 30% sweet potato flour) was 6.16% which is

congeal to the sample S2

(6.18%) containing 70% wheat flour, 5% potato flour and 25%

carrot flour.

4.3.3 Fat

The fat contents of four different cake samples processed with different levels of composite

flour were shown in Table 4.4. In present study it was observed that the fat contents of all

samples (31.68-33.64%, db) were higher than that of control sample (22.25%). It was

observed that fat contents in composite cake samples decreased (from S2 to S4) with

increasing substitution level of potato flour and decreasing substitution level of carrot flour in

composite dough.

51

This might be due to the fact that carrot flour contains highest percentage of fat

(approximately 1.18%, db) than that of potato flour (1.14%, db) and wheat flour (0.95%).

Okorie and Onyeneke (2012) reported that the fat content of the composite cake (70% wheat

flour and 30% sweet potato flour) was 30.84% (db) which is congeal to the composite sample

S4

(31.68%, db) containing 70% wheat flour, 25% potato flour and 5% carrot flour.

4.3.4 Ash

The ash (mineral) contents of four different cake samples processed with different levels of

composite flour were shown in Table 4.4. In present study it was observed that the ash

contents of all samples (1.54-2.76%, db) were higher than that of control sample (1.18%). It

was observed that fat contents in composite cake samples decreased (from S2 to S4

This might be due to the fact that carrot flour contains highest percentage of ash

(approximately 5.63%, db) than that of potato (3.1%, db) and wheat flour (0.77% fat). Okorie

and Onyeneke (2012) reported that the ash content of the composite cake (70% wheat flour

and 30% sweet potato flour) was 1.12% which is less similar to the composite sample S

) with

increasing substitution level of potato flour and decreasing substitution level of carrot flour in

composite dough.

4

Table 4.4 Composition of cakes containing different levels of composite flour

(1.54%) containing 70% wheat flour, 25% potato flour and 5% carrot flour.

Data in bracket are in dry weight basis

Components

Cake samples

S S1 S2 S3 4

Moisture (%) 21.31 (27.08) 22.12 (28.40) 24.43 (32.32) 26.93 (36.85)

Protein (%) 6.50 (8.26) 6.18 (7.93) 6.00 (7.94) 5.83 (7.97)

Fat (%) 22.25 (28.27) 26.20 (33.64) 24.38 (32.26) 23.15 (31.68)

Ash (%) 0.93 (1.18) 2.15 (2.76) 1.43 (1.89) 1.13 (1.54)

Crude fiber (%) 0.41 (0.52) 0.85 (1.09) 1.55 (2.05) 2.31 (3.16)

Total carbohydrates (%) 49.01 (62.28) 43.35 (55.66) 43.76 (57.90) 42.96 (58.79)

52

Where,

S1

S

= Control sample (with only wheat flour)

2

S

= Containing 70% wheat flour, 5% potato flour, 25% carrot flour

3

S

= Containing 70% wheat flour, 15% potato flour, 15% carrot flour

4

= Containing 70% wheat flour, 25% potato flour, 5% carrot flour

4.3.5 Crude fiber

The crude fiber contents of four different cake samples processed with different levels of

composite flour were shown in Table 4.4. In present study it was observed that the fiber

contents of all samples (1.09-3.16%, db) were higher than that of control sample (0.52%, db).

It was observed that fiber contents in composite cake samples increased (from S2 to S4

This might be due to the fact that potato flour contains highest percentage of fiber

(approximately 5.09%, db) than that of carrot flour (2.36%, db) and wheat flour (0.45%, db).

The fiber content (3.16%, db) of the cake sample S

) with

increasing substitution level of potato flour and decreasing substitution level of carrot flour in

composite dough.

4

(containing 70% wheat flour, 25% potato

flour and 5% carrot flour) was similar to those reported by Woot-Tsuen wu Leung et al.

(1972) who found 3.11% (db) fiber in composite cake containing 70% wheat flour and 30%

cassava flour.

4.3.6 Total carbohydrate

The total carbohydrate content of the cakes containing different levels of composite flour and

control cake were presented in Table 4.4. The total carbohydrate content of different cakes

varied from 55.66% to 58.79%, db being highest for control cake S1 (62.28%, db) and the

lowest for the cake sample S2 (55.66%, db). It was observed that total carbohydrates content

increased in composite cakes (from S2 to S4) with increased levels of potato flour in dough.

Okorie and Onyeneke (2012) reported that the carbohydrate content of the composite cake

(70% wheat flour and 30% sweet potato flour) was 58.32% which is as like as similar to the

composite sample S4 (58.79%, db) containing 70% wheat flour, 15% potato flour and 15%

carrot flour.

53

4.4 Sensory evaluation of the cakes containing different level of composite flour

Cake samples S1 (with only wheat flour), S2(containing 70% wheat flour, 5% potato flour

and 25% carrot flour), S3 (containing 70% wheat flour, 15% potato flour and 15% carrot

flour), and S4

One-way analysis of variance (ANOVA) (Appendix I) on sensory qualities of cakes samples

was carried out and results (Table 4.5) revealed that there were (P<0.05) differences in color

acceptability among the cakes. The finding indicates that the color of sample S

(containing 70% wheat flour, 25% potato flour and 5% carrot flour)were

subjected to sensory evaluation. The color, flavor, texture and overall acceptability of control

cake and three composite cake samples were evaluated by a panel of 10 tasters. The mean

score for color, flavor, texture and overall acceptability preference are presented in Table 4.5.

4 was more

acceptable. As shown in Table 4.5, (DMRT test) there was difference for color preference

between the cakes containing composite flour. The cake sample S4 scored better color

acceptability among all the cakes. The cake samples gained increasing preferable

acceptability gradually from S1 to S4

In case of flavor preferences among the cake samples, one-way ANOVA (Appendix II)

showed that the supplementation of cakes, with composite flour significantly (P<0.05)

affected flavor acceptability. The result (Table 4.5) points out that the flavor of sample S

.

4

was most preferred and differed from all other cake samples. The flavor of the cake samples

S1, S2 and S3 were equally acceptable. The cake sample S4 scored higher flavor acceptability

than all other cake samples while the control cake sample S1

Significant texture difference (P<0.05) were revealed between control cake and cakes

containing composite flour (Appendix III). The DMRT test for texture preference was

conducted and the findings (Table 4.5) suggested that the control cake S

scored least flavor acceptability

as compared to the other cake samples.

1 and the cake

sample S2 were equally acceptable and significantly different from the cake samples S3 and

S4. The cake sample S4 (containing 70% wheat flour, 25% potato flour and 5% carrot flour)

gained the highest score among cake samples with composite flour and control cake while

cake sample S2

obtained the lowest texture score among cakes.

54

Table 4.5 Mean sensory scores of control cake and the cakes containing composite flour

(wheat, potato and carrot flour)

Mean with same superscript within a column are not significantly different at p<0.05.

Where,

S1

S

= Control sample (with only wheat flour)

2

S

= Containing 70% wheat flour, 5% potato flour, 25% carrot flour

3

S

= Containing 70% wheat flour, 15% potato flour, 15% carrot flour

4

From the results of ANOVA (Appendix IV) it was apparent that there was significant

(P<0.05) difference in overall acceptability among the cakes. The results (Table 4.5) indicate

that the overall acceptability of the control cake S

= Containing 70% wheat flour, 25% potato flour, 5% carrot flour

1 (with only wheat flour) and sample S2

(containing 70% wheat flour, 5% potato flour and 25% carrot flour) were equally acceptable.

The DMRT test for overall acceptability preference was performed and the results (Table 4.5)

revealed and the composite cake sample S4 scored the highest score for overall acceptability

among the other cake samples. The overall acceptability of control cake sample S1 (with only

wheat flour) and composite cake sample S2 (containing 70% wheat flour, 5% potato flour and

25% carrot flour) were equally acceptable. On the other hand, the cake sample S3 and S4

were equally acceptable. It was observed that the cake sample S4

secured the highest score

Cake type

Sensory attributes

Color Flavor Texture Overall

acceptability

S 5.9001 6.000C 6.100B 6.000C B

S 6.7002 6.600BC 6.000B 6.200C B

S 7.1003 6.800AB 7.000B 7.200B A

S 7.6004 7.800A 8.100A 8.000A A

LSD (P<0.05) 0.8238 0.8863 0.8264 0.8579

55

for overall acceptability and was ‘like very much’ while control cake S1

(containing only

wheat flour) obtained the lowest score among all the cake samples.

4.5 Storage study of wheat-potato-carrot composite cake

Studies were conducted to observe the storage stability in terms of moisture gain by storing

the composite cake at room temperature (300C) and refrigeration temperature (50

Table 4.6 The effect of normal and refrigeration condition on moisture content of

composite cake

C).

Composite cake with 24.43% initial moisture content was packed in single layer polythene

and kept in the laboratory at room temperature and refrigeration temperature. The moisture

content of different composite cake was determined gravimetrically (from initial known

moisture content) at every day. Results are shown in Table 4.6 and figure 4.6.

Storage t ime

(day)

Moisture content (%)

At Room temperature

(30 0

At Refr igerat ion

temperature (5C) 0 C)

1 24.43 s t 24 .43

2 25 .27 n d 26 .13

3 26 .20 r d 27 .04

4 27 .56 t h 28 .01

5 27 .63 t h 28 .89

6 27 .66 t h 29 .58

7 27 .67 t h 30 .46

8 27 .69 t h 30 .48

56

Figure 4.6 Effect of normal and refrigeration storage condition on moisture uptake of

composite cake during storage

The results showed that the moisture uptakes by composite cake were increased continuously

throughout the investigation period for both the storage conditions. Then the moisture

contents were constant after storage period 4th day stored at room temperature and 7th

The above studies indicate that the storage stability of composite cake is 3 to 4 days at room

temperature and 6 to 7 days at refrigeration temperature packed with single layer polythene.

day

stored at refrigeration temperature respectively. This might be due to the fact that the

products approached equilibrium with relative humidity of room condition and refrigeration

conditions, respectively.

57

Chapter 5

SUMMARY AND CONCLUSION

This study reports on processing of cakes by incorporating different levels of potato and

carrot flour with standard wheat flour on flour weight basis and analyzed for their various

physical and chemical properties. Raw potato and carrot were dried and milled to produce

flour. Ready-made wheat flour from near market was also used. The cakes were prepared by

standard formulation. Wheat, potato and carrot flour used in the cakes preparation were

analyzed for proximate composition. Wheat flour contained moisture 14.46% (wb), protein

13.01% (wb), fat 0.95% (wb), ash 0.77% (wb), crude fiber 0.45% (wb) and total carbohydrate

85.26% (wb); The potato flour contained moisture 17.13%(wb), protein 6.62% (wb), fat

1.12% (wb), ash 3.1% (wb), crude fiber 5.09% (wb) and total carbohydrate 89.16% (wb);

Carrot flour contained moisture 5.67% (wb), protein 7.28% (wb), fat 1.18% (wb), ash 5.63%

(wb), crude fiber 2.36% (wb) and total carbohydrate 85.91% (wb). Control cake was prepared

from 100.0% wheat flour and composite flour cakes were processed containing 5, 15 and

25% potato flour and 25, 15 and 5% carrot flour in the formulations and evaluated for various

quality parameters.

The volume and specific volume of composite cake samples incorporated with wheat, potato

and carrot flour gave higher results than that of control cake prepared from only wheat flour.

The volume and specific volume were found of control sample S1 (with only wheat flour)

215cc and 1.30 cc/g, sample S2 (70% wheat flour, 5% potato flour and 25% carrot flour) 263

cc and 1.51 cc/g, , sample S3 (70% wheat flour, 15% potato flour and 15% carrot flour) 250

cc and 1.39 cc/g, sample S4

Moisture contents and weights of composite flour cakes were higher than that of control cake.

The moisture content and weight of composite flour cakes increased gradually with

increasing levels of potato-carrot ratio in composite flour formulations. The variations in

moisture content and weight of the cakes might result from the increased water absorption by

the composite flour.

(70% wheat flour, 25% potato flour and 5% carrot flour) 245 cc

and 1.33 cc/g respectively. Volume and specific volume decreased with the increasing level

of potato flour and decreasing level of carrot flour among the composite cake samples.

58

The cake sample S4 gained better appearance compared to other composite flour cakes in

terms of bloom, crust color and texture. Crumb color of all composite cake samples became

reddish yellow. But there were visible difference among its color brightness. Sample S2

containing 5% potato flour and 25% carrot flour, sample S3 containing 15% potato flour and

15% carrot flour and sample S4 containing 25% potato and 5% carrot flour gained 50%, 25%

and 10% darker respectively. In respect of color brightness sample S4

Sensible difference of crumb flavor was observed between cake sample S

was most preferable.

4 containing 25%

potato and 5% carrot flour and other types of cake samples. Control sample (without

composite flour), sample S2 and sample S3 were equally acceptable. Sample S4

In case of crumb texture control sample and sample S

was most

acceptable in respect to flavor.

2 were equally acceptable. Sample S4

The cakes (both control and composite flour cakes) were analyzed for their composition. It

was observed that cakes from composite flour secured higher amount of moisture, fat, ash,

and crude fiber than cake from only wheat flour (i.e. control). A sharp increase in moisture

and crude fiber content were observed with increase of potato-carrot flour mixing ratio in

cake formulation. On the other hand, a sharp decrease in protein, fat and ash content were

observed with increase of potato-carrot flour mixing ratio in cake formulation. The

moisture, protein, fat, ash, crude fiber and carbohydrate contents in the composite flour cakes

samples were found in the range of 28.40-36.85% (db), 7.93-7.97% (db), 31.68-33.64% (db),

1.54-2.76% (db), 1.09-3.16% (db), and 55.66-58.79% (db) respectively. A statistical analysis

on the response of taste panel on the sensory properties of cakes supplemented with

composite flour revealed that the color, flavor, texture and overall acceptability of different

cakes were significantly (P<0.05) different. The color and flavor of the cake sample S

was most acceptable.

4 was

better than those of the cake samples S1, S2 and S3. The flavor acceptability of control cake,

sample S2 and S3 were equally acceptable. The texture preference of sample S4 was better

than the other composite flour cake samples. The overall acceptability of control cake and the

cake sample S2 were equally acceptable. As evident, the color, flavor, texture and overall

acceptability of the cake sample S4

was found to be most acceptable among the cake samples

with composite flour and control sample.

59

This study has demonstrated that incorporation of different levels of potato and carrot flour

(vegetable flour) to the cake formulation has improved the cake quality attribute especially

color, texture, flavor, volume, weight, fat, minerals, crude fiber than that of ordinary cake,

thus development of new wheat-potato-carrot product variety. On the basis of composition

and organoleptic evaluation of the processed cakes, it may be concluded that good quality

composite flour cake sample S4

The storage stability of composite cake sample was observed by storing it in room

temperature (30

may be processed incorporating 70% wheat flour, 25%

potato flour and 5% carrot flour for improved nutritional value and sensory properties. This

cake formulation may be preferred for vegetable complement in our body. The current study

aimed at producing and evaluating the quality properties of cake made the composite of

wheat, potato and carrot flours as a strategy to improve potato and carrot utilization and

improvement of smallholder income and livelihood.

0C) and refrigeration temperature (50

C) packaging with single layer

polythene. The observation showed that the stability of composite cake was 3 or 4 days for

room temperature storage and 6 to 7 days for refrigeration temperature storage. The

refrigeration storage provided better storage stability than that of room temperature. The

refrigeration storage recommends the slow rate of approaching equilibrium with relative

humidity of storage condition and inactivation or slow of microbial growth. Hence

refrigeration storage is more preferable.