wet milling properties of waxy wheat flours by two laboratory methods

www.elsevier.com/locate/jfoodeng

Journal of Food Engineering 72 (2006) 167–178

Wet-milling properties of waxy wheat flours by twolaboratory methods q

Abdulvahit Sayaslan a,*, Paul A. Seib b, Okkyung K. Chung c

a Department of Food Engineering, Gaziosmanpas�a University, 60240 Tokat, Turkeyb Department of Grain Science and Industry, Kansas State University, Manhattan, 66506 KS, USA

c USDA/ARS Grain Marketing and Production Research Center, Manhattan, 66502 KS, USA

Received 7 July 2004; accepted 18 November 2004

Available online 18 January 2005

Abstract

Straight-grade flours roller-milled from seven waxy and two control (nonwaxy and partial waxy) wheats (Triticum aestivum) were

wet-milled by dough-washing (DW) and dough-dispersion and centrifugation (DD&C) methods to give starch, gluten, tailings, and

water-solubles fractions. Compared to the controls, flour yields of the waxy wheats were lower. The waxy flours contained more

crude fat and pentosans and less total starch. Gluten proteins of the waxy flours appeared to be weaker. By the DW method, both

of the controls but only two of the seven waxy flours could be wet-milled. The remaining five waxy flours failed in the DWmethod as

their doughs lost cohesiveness and elasticity during kneading and washing under water. Those waxy flours were instead wet-milled

by the modified DW method, where the doughs were gently hand-rubbed on a 125-lm opening screen to facilitate the passage of the

starch and water-solubles through while retaining the gluten agglomerates on the screen. The prime starch and tailings of the waxy

flours were not separated as visibly as those of the controls during their centrifugal purification, which in turn led to a reduction in

yields and purities of their prime starch and gluten fractions. On the other hand, the wet-milling characteristics of the waxy flours by

the DD&C method were comparable to those of the controls because the DD&C method is apparently less dependent than the DW

method on the gluten aggregation traits of flours.

� 2004 Elsevier Ltd. All rights reserved.

Keywords: Waxy wheat flour; Wet-milling; Starch and Gluten separation

1. Introduction

Wheat is among the leading cereal grains produced in

the world, and is used for food (67%), feed (20%), and

seed (7%). The industrial uses of wheat, which also in-

cludes its wet-milling to produce starch and vital gluten

as the major co-products, account for �6% of total pro-

0260-8774/$ - see front matter � 2004 Elsevier Ltd. All rights reserved.

doi:10.1016/j.jfoodeng.2004.11.033

q Mention of firm names or trade products does not imply that they

are endorsed or recommended by the USDA, Kansas State University,

or Gaziosmanpas�a University over other firms or products not

mentioned.* Corresponding author. Tel.: +90 3562521616x3262; fax: +90 356

2521488.

E-mail address: [email protected] (A. Sayaslan).

duction. Common or bread wheats (Triticum aestivum)

with hard or soft endosperm constitute about 95% of to-

tal production, whereas durum wheat (Triticum durum)

accounts for �5%. Durum and hard wheats contain

more protein (12–16%) than do soft wheats (8–10%)

(Oleson, 1994; Seib, 1997; USDA/NASS, 2001). Hard

and soft wheats are roller-milled to flour and commonly

used for producing yeast-leavened breads and rolls asthey form strong viscoelastic doughs when mixed with

water. Soft wheat flours, however, give weak doughs

and are thus preferred for cakes, cookies and crackers.

Durum wheat with the hardest endosperm among

wheats is milled to semolina and used in pasta and cous-

cous production due to its strong gluten elasticity and

desirable yellow color. Hard or soft wheat flours with

mailto:[email protected]

168 A. Sayaslan et al. / Journal of Food Engineering 72 (2006) 167–178

weak- to medium-strength gluten are suitable for the

Asian noodles, steam breads, and flat breads (Oleson,

1994; Posner, 2000; Seib, 1997). For wet-milling to pro-

duce wheat starch and vital wheat gluten, straight-grade

or high-yield flours from hard or soft wheats with high-

protein content (>11%), good mixing quality (stronggluten aggregation), and low starch damage, ash, and

a-amylase activity are preferred (Maningat & Bassi,

1999). Wheat starch is used in a vast variety of food

and nonfood applications in unmodified or modified

forms; such as acid-thinned, bleached, oxidized, cross-

linked, substituted, cross-linked/substituted, and other

doubly modified starches (Maningat & Seib, 1997).

Wheat starch also is converted to starch hydrolysisproducts, such as sweeteners (Schenck & Hebeda,

1992). Vital wheat gluten is a valuable co-product of

wheat wet-milling process that yields wheat starch

(Bergthaller, 1997; Cornell & Hoveling, 1998; Grace,

1988; Maningat & Bassi, 1999; Maningat, Bassi, & Hes-

ser, 1994). Vital wheat gluten is used in breakfast cereals

and snacks, meat and cheese analogs, breading and bat-

ter mixes, pizza, and in meat, fish, and poultry products(Bergthaller, 1997; IWGA, 1989; Maningat & Bassi,

1999). Wheat gluten also is of great importance as an

industrial protein, and is converted to wheat protein iso-

late, hydrolyzed wheat protein, and texturized or deam-

idated wheat gluten (Bergthaller, 1997; Maningat et al.,

1994; Maningat, DeMeritt, Chinnaswamy, & Bassi,

1999).

Five industrial wet-milling processes that start withflour rather than wheat kernel have been employed to

isolate wheat starch and vital wheat gluten (Maningat

& Bassi, 1999; Seib, 1994). Until the mid 1970s, wheat

starch had been produced primarily by the Martin pro-

cess that was invented in 1835 (Anderson, 1967; Barr,

1989; Fellers, 1973; Zwitserloot, 1989a) and rarely by

the Batter process developed in 1944 (Anderson, 1967,

1974; Fellers, 1973). Then, the Alfa-Laval/Raisio (Dahl-berg, 1978; Kerkkonen, Laine, Alanen, & Renner, 1976;

Maijala, 1976) and Hydrocyclone (Verberne & Zwitser-

loot, 1978; Verberne, Zwitserloot, & Nauta, 1979) pro-

cesses were introduced. The most recent wet-milling

process commercialized in 1984 is the High-Pressure

Disintegration (HD) process (Bergthaller, Lindhauer,

& Zwingelberg, 1998; Meuser, Althoff, & Huster, 1989;

Witt, 1997; Zwitserloot, 1989a, 1989b). The Martinand Batter processes are considered the traditional pro-

cesses, whereas the Alfa-Laval/Raisio, Hydrocyclone,

and HD processes are deemed the modern-day aqueous

dispersion processes. Currently, the Martin (modified

modern versions), Hydrocyclone, and Alfa-Laval/Raisio

processes are commonly used in North America, and the

HD process is popular in Europe (Maningat & Bassi,

1999). The Batter process was mostly abandoned. Theadvantages of the aqueous dispersion processes include

a reduction in fresh water consumption, an increase in

prime starch yield, and less sensitivity to gluten protein

aggregation characteristics during wet processing (Zwit-

serloot, 1989a, 1989b). For details on the industrial wet-

milling processes for wheat flour, the reader is referred

to a recently published review by Sayaslan (2004).

Common wheats are hexaploid with three sets ofchromosomes, but they differ in the translation of gran-

ule-bound starch synthase isozymes in their kernels

(Yamamori & Quynh, 2000). Wild-type (nonwaxy or

typical) wheats contain all three possible waxy proteins

(Wx-A1, Wx-B1, and Wx-D1) and thus possess normal

level (�28%) of amylose in the starch. Partial waxy

wheats are null for one or two of the three waxy pro-

teins, which results in reduced level of amylose (�20–26%). Waxy wheats are, however, triple-null for all the

three waxy proteins and their starch contains <1% amy-

lose (Kim, Johnson, Graybosch, & Gaines, 2003; Seib,

2000). Besides commonly grown nonwaxy and partial

waxy wheats, waxy wheats with hard or soft endosperm

have been developed recently and may find uses in wet-

milling for waxy starch production, extruded products

for volume expansion, frozen foods and doughs forcold-temperature stability, bakery products for shelf-life

extension and fat replacement, instant food products for

easy-to-cook trait (Bhattacharya, Erazo-Castrejon,

Doehlert, & McMullen, 2002; Graybosch, 1998), and

for other purposes yet to be discovered. The low gelati-

nization temperature of waxy wheat starch compared to

waxy corn starch may be important in microwaved

foods. Hydroxypropylated and cross-linked waxy wheatstarch gave a thick paste with high-cold temperature

stability. Cross-linking waxy wheat starch, akin to

cross-linked waxy corn starch, imparts high and stable

viscosity to processed foods (Reddy & Seib, 2000).

Maltodextrins with dextrose equivalents of �1 and

�10 were successfully produced from waxy wheat

starches because of their lower levels (<0.1%) of lipids

(Lumdubwong & Seib, 2001).Waxy wheats were first developed in 1994 through

conventional plant breeding in Japan (Nakamura,

Yamamori, Hirano, Hidaka, & Nagamine, 1995), and

later in Canada (Chibbar, Baga, Demeke, & Hucl,

1997) and in the USA (Graybosch, 1998; Morris & Kon-

zak, 2001; Souza, 2001—personal communication). Waxy

wheats also have been produced through mutagenesis of

partial waxy wheats Kanto 107 or Ike (Kiribuchi-Otobe,Nagamine, Yanagisawa, Ohnishi, & Yamaguchi,

1997; Yasui, Sasaki, Matsuki, & Yamamori, 1997; Kon-

zak, 1998—personal communication). Physical/chemical

properties of waxy wheat starches have been thoroughly

studied. Hexaploid waxy wheat starch was found to con-

tain 0.9 to 3.2% apparent amylose and 0.12–0.29% lipids

(Abdel-Aal, Hucl, Chibbar, Han, & Demeke, 2002; Cha-

kraborty et al., 2004; Kim et al., 2003; Yasui, Matsuki,Sasaki, & Yamamori, 1996), in contrast with 22–25%

amylose and 0.8–1.2% lipids in nonwaxy wheat starch

A. Sayaslan et al. / Journal of Food Engineering 72 (2006) 167–178 169

(Morrison, Milligan, & Azudin, 1984). As expected,

waxy wheat starch showed the A-type X-ray pattern

and had an increased level of crystallinity compared to

wild types, thereby elevating the enthalpy of gelatiniza-

tion (Chakraborty et al., 2004; Fujita, Yamamoto,

Sugimoto, Morita, & Yamamori, 1998; Hayakawa, Ta-naka, Nakamura, Endo, & Hoshino, 1997; Kim et al.,

2003; Sasaki, Yasui, & Matsuki, 2000). Tetraploid (dur-

um) waxy wheat starches also showed similar gelatiniza-

tion and pasting properties (Chakraborty et al., 2004;

Grant et al., 2001). Although physical and/or chemical

properties of waxy wheat starches have been the focus

of much research, wet-milling properties of waxy wheat

flours and their gluten fractions are yet to be studied.The objective of this study was therefore to determine

the wet-milling properties of waxy wheat flours by two

laboratory methods that simulate the traditional Martin

and aqueous dispersion processes.

2. Materials and methods

2.1. Materials

Six experimental waxy wheat lines were obtained

from Dr. C.F. Konzak (Northwest Plant Breeding

Co., Pullman, WA), Dr. R.A. Graybosch (USDA/

ARS, University of Nebraska, Lincoln, NE), Dr. C.F.

Morris (USDA/ARS-WWQL, Washington State Uni-

versity, Pullman, WA), and Dr. R.N. Chibbar (NationalResearch Council, Plant Biotechnology Institute, Saska-

toon, SK, Canada). One of the samples was received as

flour. The waxy wheat samples were coded as follows:

Wx-A, Wx-B, Wx-C, Wx-1, Wx-2, and Wx-3. All of

the samples were experimental waxy wheat lines, but

the Wx-1, Wx-2, and Wx-3 wheats were reportedly in

their advanced stages of field trials and selection for

agronomic traits. Leona waxy wheat sample, a waxywheat variety, was provided by Dr. E.J. Souza (Univer-

sity of Idaho, Aberdeen, ID). Control nonwaxy (Karl

92) and partial waxy (Ike) wheats were from Dr. J. Mar-

tin (Hays Branch of State Agricultural Experiment Sta-

tion, Kansas State University, Manhattan, KS). The

waxy wheats used in the study were reportedly produced

by either mutagenesis of Ike partial waxy wheat, or by

crossing Ike or Kanto 107 partial waxy wheat with BaiHuo partial waxy Chinese wheat. Some of the waxy

wheats were further backcrossed with Klasic wheat.

2.2. Methods

2.2.1. General methods

Wheat samples were cleaned on a Carter-Day dock-

age tester (Carter-Day Co., Minneapolis, MN) and theirtest weights measured with a test weight apparatus from

Burrows Equipment Co., Evanston, IL. Single kernel

characteristics of wheat samples were determined on

the Single Kernel Characterization System (SKCS

4100, Perten Instruments North America, Inc., Reno,

NV). All wheat samples were tempered at 15.5% mois-

ture for 20 h and roller-milled to straight-grade flours

on a Buhler experimental mill (Buhler Co., Uzwil, Swit-zerland). Lightness values (L*) of flours were measured

using a Minolta Chroma Meter (Minolta Co., Osaka,

Japan).

Moisture, ash, crude fat, and crude fiber contents

were determined by the American Association of Cereal

Chemists (AACC, 2000) methods 44-15A, 08-01, 30-25,

and 32-10, respectively. Protein contents (N · 5.7) weremeasured by combustion method on an FP Protein/Nitrogen Analyzer (Leco Corp., St. Joseph, MI). Total

starch and starch damage were determined by the

AACC methods 76-13 and 76-31, respectively, using

assay kits from Megazyme International Ireland Ltd.,

Wicklow, Ireland. Amylose contents of flours and a-amylase activities of wheat kernels were measured

using, respectively, amylose/amylopectin and Ceralpha

a-amylase assay kits from Megazyme InternationalIreland Ltd., Wicklow, Ireland.

Mixograms of flours were obtained by the AACC

method 54-40A using a 10-g mixograph (National Man-

ufacturing Co., Lincoln, NE). The mixograms were

interpreted as described by Finney and Shogren

(1972). Gluten index (GI) and falling number of flours

were determined, respectively, on Glutomatic and Fall-

ing Number instruments (Perten Instruments NorthAmerica, Inc., Reno, NV) by the AACC methods

38-12 and 56-81B, respectively.

Insoluble polymeric protein (IPP) contents of flours

were determined essentially by the method of Bean,

Lyne, Tilley, Chung, and Lookhart (1998). Flour

(1.0 g, db) was mixed with 4 ml of 50% (v/v) aqueous

1-propanol and the mixture dispersed by hand with a

spatula. The sample was mixed continually for 5 minon a vortex mixer, centrifuged at 8160g for 5 min, and

the supernatant discarded. This extraction procedure

was done a total of three times. After the extractions,

the pellet was freeze-dried and analyzed for protein

(N · 5.7). The IPP content was calculated as a percent-

age of total protein in a flour sample.

Sodium dodecyl sulfate (SDS) sedimentation volumes

of flours were determined by the AACC method 56–70with modifications. Flour (2.0 g, 14% mb) was weighed

into a 100-ml graduated cylinder and 20.0 ml of water

containing 0.0004% bromophenol blue (w/v) was added.

The cylinder was capped and hand-shaken for 15 s, then

placed on a specially designed (USDA/ARS Grain Mar-

keting and Production Research Center, Manhattan,

KS) table-top wrist-action shaker for 225 s at room tem-

perature. Next, 20.0 ml of 2.5% (w/v) aqueous SDS solu-tion was added. After gently shaking, the cylinders were

placed on the shaker for another 6 min. Finally, 10.0 ml


of 0.47% (v/v) lactic acid solution was added and the cyl-

inder placed on the shaker for 6 min. The cylinder was

removed and placed on a rack with a back lighting for

20 min prior to reading sedimentation volume.

Total and soluble pentosans in flours were estimated

according to colorimetric method of Douglas (1981).The concentration of pentose sugar DD-xylose after

acid-catalyzed hydrolysis of pentosans in a flour (for to-

tal pentosan assay) or in its water extract (for soluble

pentosan assay) was estimated from a DD-xylose standard

curve. Soluble pentosans were extracted from a flour

prior to colorimetric determination according to

Hashimoto, Shogren, and Pomeranz (1987). Flour

(100 mg, 14% mb) was weighed into a stoppered 15-mlglass tube, 10.0 ml of distilled water added and the tube

shaken at 30 �C in a reciprocal water bath (Precision

Instruments, Winchester, VA) at a medium speed for

2 h. The sample was then centrifuged at 2000g for

5 min and the supernatant collected for determination

of soluble pentosans. Soluble and total pentosans were

presented as % DD-xylose (Douglas, 1981).

Granule size distributions of starches were deter-mined on a laser-diffraction particle analyzer (Leco-

trac-LTS150, Leco Corp., St. Joseph, MI) equipped

with a recirculator, an on-line ultrasonic probe, and an

interfaced computer with Lecotrac software. Starch

(�0.2 g) was mixed with distilled water (5 ml) and al-

lowed to stand at room temperature for 24 h. After vig-

orous agitation by hand, the suspension (�1–2 ml) wasadded to isotonic buffer solution (300 ml) (sodium chlo-ride, 8.6 g/L; potassium chloride, 0.38 g/L; ethylenedia-

mine tetraacetic acid, 0.4 g/L; 2-phenoxyethanol, 0.2 g/

L; in deionized water) being circulated at 40 ml/s

through a standard cell. The addition of the starch/water

mixture was stopped when the particle analyzer pro-

duced a signal indicating that a sufficient number of par-

ticles were present for analysis. Then the ultrasonic

device was energized for 60 s prior to particle size mea-surement. The software converted the diffracted light

data to particle diameters between 0.7 and 700 lm,and the volume percentages of particles were calculated

assuming that the particles were spheres.

2.2.2. Wet-milling of flours by dough-washing (DW)

method

Wheat flours were fractionated by the AACC glutenhand-washing method 38-10 with modifications, which

resembles the traditional Martin (dough-washing) pro-

cess, to give wet gluten, prime starch, tailings, and water

solubles. Flour (100 g, 14% mb) in a 100-g bowl pin mix-

er (National Manufacturing Co., Lincoln, NE) was

mixed with gradual addition of water (60–70 ml,

25 �C) until the mixture became a cohesive, stiff

dough-ball and cleaned itself from the mixing bowl(3–5 min). After resting the dough under a moist cover

for 1 h at room temperature, the dough was hand-

kneaded gently under a stream of water over a 125-lmopening sieve until almost all starch and soluble materi-

als were removed. However, certain doughs failed to

maintain their cohesive and elastic properties during

hand-kneading under water. To facilitate the wet-

separation of starch and gluten, those doughs were in-stead gently hand-rubbed on the screen under a spray

of water to allow the passage of the starch and water-

solubles while retaining the gluten protein agglomerates

on the screen. This method of wet-milling was in this

work called the modified dough-washing (MDW) meth-

od. Washing of the gluten mass by both the methods

(DW and MDW) was stopped when 1–2 drops of water

squeezed from the gluten into a beaker gave clear waterfree of starch granules. The gluten fraction was placed in

a container, covered, and stored at room temperature

for 1h. The wet gluten was then shaped into a sphere,

pressed as dry as possible between a pair of watch

glasses, and weighed. Wet gluten was partly frozen in

freezer (�1 h), cut into �1-cm3 pieces, and placed in jars

that were attached to a freeze-dryer (Flexi-Dry/MP,

TMS Systems, Inc., Stone Ridge, NY). The reducedpressure caused the gluten pieces to expand and created

a high-surface area for rapid freeze-drying. The freeze-

dried gluten, which typically contained <5% moisture,

was ground in a Thomas-Wiley intermediate mill (Tho-

mas Scientific Co., Philadelphia, PA) to pass through a

420-lm opening sieve.

The so-called starch milk, which passed through the

125-lm opening sieve, was resieved through a 75-lmopening sieve, and the mass remaining over the 75-lmopening sieve was washed with water (50 ml). The mate-

rial that remained atop the screen was collected. The

material passing through the 75-lm opening sieve was

centrifuged at 2500g for 20 min, and the supernatant

was collected. The upper-pigmented layer (tailings) atop

the white starch was carefully removed with a spatula.

The starch was resuspended by hand-shaking in water(200 ml) and centrifuged at 2500g for 20 min. The super-

natant was collected, combined with the supernatant

collected in the first centrifugation step, and sampled

(100 ml) to determine water-soluble solids. The tailings

were carefully removed with a spatula. The remnants

of the 75-lm opening sieve and the tailings removed

after the first and second centrifugation steps were com-

bined and freeze-dried. The starch on the bottom layerwas collected and oven-dried at 40 �C for two days.

The dried starch (�8% moisture) was gently ground

with a mortar and pestle before being analyzed for mois-

ture and protein.

2.2.3. Wet-milling of flours by dough-dispersion and

centrifugation (DD&C) method

Wheat flours were fractionated into wet gluten, primestarch, tailings, and water-solubles by essentially a

dough-dispersion and centrifugation (DD&C) method


reported by Czuchajowska and Pomeranz (1993, 1995),

which somewhat simulates the aqueous dispersion pro-

cesses. Dough preparation step was similar to that in

the DW method. The developed stiff dough-ball was

covered with water––a total of 200 ml of water including

that added to the flour in the dough mixing stage. Afterresting for 30 min at room temperature, the dough and

liquid were transferred to a Waring blender and dis-

persed at high speed for 1 min. The dry solids concentra-

tion of the slurry was adjusted to �27% with additional

water prior to centrifugation at 2500g for 15 min. Upon

centrifugation, the supernatant was collected and the

top layer of sediment, which consisted mainly of gluten

plus insoluble pentosans, damaged starch, and smallgranular starch, was carefully removed from the prime

starch layer (bottom). The top layer was gently manipu-

lated under a stream of water (3 · 200 ml) to obtain the

cohesive gluten fraction. The gluten fraction was treated

similarly to those in the DW method to obtain dry glu-

ten. The prime starch layer and the washings (starch

milk) of the gluten fraction were combined and purified

by washing with water and centrifugation twice as de-scribed in the DW method.

2.2.4. Data analysis

Gluten and starch separation and the physical/chem-

ical analyses were carried out at least in two replications,

and the means were compared by the Tukey�s HSD test

in one-way analysis of variance (ANOVA), using the

Statistical Analysis System Software, V. 6.12 (SAS Insti-tute, Inc., Cary, NC).

3. Results and discussion

3.1. Wheat kernel properties

Karl 92 and Ike wheats are both the U.S. hard redwinter wheat varieties. Karl 92 is a nonwaxy wheat that

contains all three waxy proteins (Wx-A1, Wx-B1, and

Wx-D1) and thus possesses normal level (�28%) of

amylose in its starch. Ike wheat is a partial waxy wheat,

double-null for the Wx-A1 and Wx-B1 proteins, with re-

duced amylose (�21%). The waxy wheats are, however,triple-null for all the three waxy proteins and their

starches contain <1% amylose (Graybosch et al., 1998;Seib, 2000). The waxy wheats often contain Ike partial

waxy wheat in their genetic backgrounds.

The waxy wheat lines used in the study were pro-

duced by either mutagenesis of Ike, or by crossing Ike

or Kanto 107 wheats, both null for the Wx-A1 and

Wx-B1 proteins, with a Chinese wheat cultivar Bai

Huo null for the Wx-D1 protein. Some of the waxy lines

were further backcrossed with Klasic wheat. All wheatsamples were sound with no sprout damage; the a-amy-lase activities ranged from 0.07 to 0.20 Ceralpha units/g

kernel and the falling numbers of the control flours were

well above 400 s (Table 1). The falling number of only

one waxy flour sample (Wx-3) was determined. In accor-

dance with the previous findings (Abdel-Aal et al., 2002;

Graybosch, Guo, & Shelton, 2000) that the Wx-3 waxy

flour gave an extremely low falling number (75 s) eventhough it was milled from a sample of sound kernels

with a low a-amylase activity (0.12 Ceralpha units/g ker-nel). In sound waxy and nonwaxy wheat flours, a-amy-lase activities were reported to range from 0.04 to 0.16

Ceralpha units/g flour (Abdel-Aal et al., 2002; Gray-

bosch et al., 2000; Yasui, Sasaki, & Matsuki, 1999),

while a sprout-damaged wheat flour had an a-amylaseactivity of 0.33 (Graybosch et al., 2000).

The waxy wheats possessed hard, soft, and mixed-

hardness endosperms, whereas the control wheats had

hard endosperms (Table 1). All waxy wheat lines and

the control wheats contained relatively high levels of

protein, ranging from 12.8% to 14.9% (14% mb). Leona

waxy wheat, however, contained the lowest protein

(10.6%). The test weights of the waxy wheats were with-

in the range of the control wheats (76–80 kg/hL) exceptfor the Wx-2 (74 kg/hL) and Wx-3 (73 kg/hL) lines. A

large variation was observed in terms of single kernel

weights (�26–40 mg). Single kernel diameters of the

waxy wheats were in general close to those of the control

wheats (�2.5 mm), with a minimum of 2.0 mm to a

maximum of 2.8 mm (data not shown).

3.2. Flour properties

Flour composition and properties are listed in Table

1. All waxy wheat samples gave less flour than the con-

trol hard wheats by roller-milling. It was noticed that

the fractions of shorts from the waxy wheats, specifically

from soft waxy wheats, were heavily contaminated with

flour. In order to recover the contaminated flour, the

shorts were sieved (150 lm opening sieve, 2 min) andthe recovered flours were combined with their respective

flours. Still, the flour yields from the waxy wheats were

�3–7% lower than the two control wheats. The Wx-2

sample gave even less flour (�15%), which was perhaps

caused by its quite small (2.0 mm) kernel size. The re-

duced flour yields from the waxy wheats with soft endo-

sperm may be explained by the typical inferior bolting

quality of soft wheats (Posner & Hibbs, 1997). Also, softwheats were milled on a Buhler experimental mill that

was set for hard wheat milling. Souza (2001—personal

communication) reported that soft waxy wheat endo-

sperm tended to flake on the smooth reduction rolls dur-

ing milling. The test weights of neither the controls nor

the waxy wheats correlated with their flour yields. The

reduced flour yields from the waxy wheats with hard

endosperm, however, might be explained by theirelevated crude fat and pentosan contents (Table 1).

Fats provide cohesiveness to flours and reduce their

Table1

Compositionandproperties

ofstraight-gradeflours

roller-m

illedfrom

controlandwaxywheatsamples

Floursample

Kernel

hardness

index

(HI)

Flour

yield

(%)

Falling

number

(s)

Proteina

(N·5.7)(%

)

Ash

a

(%)

Crudea

fiber

(%)

Crudea

fat(%

)

Starcha

(%)

Starcha

damage

(%)

Amylose

(%)

IPP

(%)

SDS

(ml)

Gluten

index

(GI)

Pentosansa

(%DD-xylose)

Color

(L*)

Total

Soluble

Controlwhea

ts

Karl92(nonwaxy)

71

71.9

492

12.1

0.49

0.21

0.8

68.0

6.2

27.6

42.4

3.7

99

1.52

0.57

91.8

Ike(partialwaxy)

75

70.8

437

12.9

0.44

0.19

0.6

68.5

4.8

21.3

37.7

3.5

98

1.36

0.47

90.9

Waxy

whea

ts

Wx-A

77

66.1

ndb

12.0

0.46

0.25

0.9

63.3

5.8

1.2

38.3

2.8

nmc

2.30

0.47

91.3

Wx-B

68

67.1

nd

12.0

0.48

0.26

0.9

64.2

5.1

1.4

29.7

1.8

nm

2.08

0.60

91.4

Wx-C

31

66.8

nd

13.1

0.41

0.24

1.0

65.9

3.7

0.9

39.4

2.7

nm

1.97

0.60

93.6

Wx-1

nrd

nr

nd

14.2

0.48

0.30

1.2

61.9

4.5

1.6

24.7

1.3

nm

1.98

0.54

90.1

Wx-2

22

60.4

nd

10.9

0.37

0.20

1.0

64.6

3.2

0.9

28.8

2.2

nm

1.74

0.56

93.5

Wx-3

44

69.2

75

13.6

0.36

0.20

0.9

64.2

6.0

0.6

37.1

3.2

nm

1.74

0.60

91.4

Leona

48

67.2

nd

9.4

0.56

0.20

1.1

66.5

4.6

1.4

24.6

1.5

nm

1.86

0.44

93.0

a14%

flourmoisture

basis(flourmoisture

levelsranged

from

11.5to

13.5%).

bNotdetermined

aswaxywheatflours

giveunusuallylowfallingnumbersindependentoftheir

a-amylase

activities.

cNotmeasureddueto

blindingofGlutomaticwashingchamber

sieve(88-lm

opening)duringglutenwashing.

dNotreported

since

itwasreceived

asflour.


flowability (Neel & Hoseney, 1984). Yasui et al. (1999)

reported reduced (20%) flour yields from two waxy

wheats produced from Kanto 107 by mutagenesis. They

attributed the decrease in waxy flour yield to a decline in

their flowability that might be caused by their elevated

fat (�20%) and b-glucan (�30) levels. Kim et al.(2003) also found that waxy wheats yielded less flour

than partial waxy and nonwaxy wheats. However, the

elevated crude fat contents determined for waxy wheat

flours might be considered an artifact of the lipid extrac-

tion. With essentially no amylose present, there is noth-

ing to bind flour lipids, hence rendering the lipids more

accessible to the solvent and inflating the values.

The protein contents of the waxy flours ranged from9.4% to 14.2% compared to 12.1% to 12.9% for the con-

trols (Table 1). The lightness values (L*) of the flours

varied from 90.1 to 93.6. As compared to the control

flours, the waxy flours contained 20–40% more fat,

10–20% more total pentosans, and 10–30% more crude

fiber. Also, waxy wheat flours had �3–7% lower total

starch than the controls, perhaps because the flux of car-

bohydrates into starch was diminished due to the ab-sence of amylose biosynthesis. Amylose levels of the

waxy samples were higher than the expected levels, rang-

ing from 0.6% to 2.3%, whereas the controls gave the ex-

pected values (Table 1). Other investigators (Abdel-Aal

et al., 2002; Chakraborty et al., 2004; Kim et al., 2003)

also reported varying amylose levels (0.9–3.2%) for

waxy wheats. This discrepancy could be attributed to

the variations in samples and methods of analysis usedin different studies.

3.3. Wet-milling properties of flours by dough-washing

(DW) method

All wheat samples were separately roller-milled to

straight-grade flours, physically and/or chemically char-

acterized, and wet-milled to give wet gluten, primestarch, tailings, and water solubles fractions. The two

control flours and only two of the waxy wheat (Wx-1

and Wx-3) flours could be wet-milled by the original

DW method (Table 2). The doughs from those flours

maintained their cohesiveness and elasticity during

kneading and washing under water, thus enabling wash-

ing of the starch from the gluten fraction. The remaining

five waxy wheat flour doughs lost much of their cohesiveand elastic properties immediately upon starting to

knead under the stream of water, despite the fact that

cohesive stiff doughs were initially formed from all the

flours, including the waxy flour doughs whose gluten

agglomerates were broken apart into small pieces and

became sticky during washing. In order to wash the

starch away and isolate the gluten, those doughs were

wet-milled by hand-rubbing them on the 125-lm open-ing screen (modified DW method, MDW). Gentle rub-

bing and washing of the small dough pieces and gluten

Table2

Wet-m

illingdata

forwheatflours

bydough-washing(D

W)ormodified

dough-washing(M

DW)methodon100g(14%

mb)offlour

Floursample

Flour

Wetgluten

Dry

glutenfraction

Starchfraction

Solublea

solids(%

)

Unaccounteda

solids(%

)Proteinb

(N·5.7)

(%)

Yieldb(%

)Glutena

yield

(%)

Proteina

(N·5.7)(%

)

Protein

recovery(%

)

Starcha

yield

(%)

Proteina

(N·5.7)(%

)

Starch

recovery(%

)

Controlwhea

ts

Karl92(nonwaxy)(byDW)

12.1

30.4

11.9

92.0

77.9

63.2

0.24

79.9

3.8

21.1

Ike(partialwaxy)(byDW)

12.9

37.9

14.2

90.9

86.2

60.6

0.21

76.0

3.7

21.5

Waxy

whea

ts

Wx-A

(byMDW)

12.0

36.8

13.4

73.8

71.1

54.3

0.40

73.8

5.8

26.5

Wx-B

(byMDW)

12.0

48.9

15.9

70.3

80.0

55.1

0.49

73.9

6.2

22.8

Wx-C

(byMDW)

13.1

44.2

16.5

73.0

79.1

56.3

0.38

73.5

6.3

21.0

Wx-1

(byDW)

14.2

54.9

17.7

73.1

78.3

56.3

0.32

78.1

9.6

16.4

Wx-2

(byMDW)

10.9

33.0

12.3

82.2

79.9

58.7

0.20

78.2

8.3

20.7

Wx-3

(byDW)

13.6

45.7

16.5

81.6

85.0

53.9

0.20

72.1

9.5

20.2

Leona(byMDW)

9.4

25.9

9.0

77.6

63.6

52.4

0.35

67.8

9.9

28.8

Tukey�sHSD

(a=0.05)

–4.9

1.5

4.4

10.3

6.5

0.09

7.4

1.4

7.0

aDry

basis.

b14%

flourmoisture

basis.


agglomerates on the sieve retained gluten agglomerates

on the sieve while allowing the starch granules and the

soluble solids to pass through the screen. Because of

the stickiness of their glutens, many of the screen open-

ings became plugged during washing, which increased

the time and water usage required to purify the glutenfraction. Interestingly, the wet gluten fractions retained

on the screen recovered their elasticity and cohesiveness

during washing at a point where about two-thirds or

more of the starch were washed away from the gluten

fractions. This may be explained by the increase in the

concentration of the gluten proteins in the gluten frac-

tions and/or removal of an unknown component from

the dough mass, which enabled the gluten proteins tointeract with each other, agglomerate, and provide cohe-

siveness. Furthermore, when the starch milk passing

through the screen from the waxy flour dough washings

were centrifuged to recover the starch fraction, a thick

intermediate fraction (tailings) was found between the

supernatant and the bottom prime starch layer. The

intermediate layer contained gluten protein particles

mixed with mostly small starch granules and insolublepentosans. In contrast, centrifugation of the starch milk

from the control flours gave a sharp interface between

the supernatant and sedimented starch with only a thin

layer of tailings (darkened zone) atop the starch.

Other investigators (Hamer, Weegels, Marseille, &

Kelfkens, 1989; Meuser, 1994; Meuser et al., 1989; Wee-

gels, Marseille, & Hamer, 1988; Zwitserloot, 1989a)

have reported differences in the rate and extent of glutenagglomeration during wet-processing of wheat flours.

The reasons for the reduced rate and strength of gluten

agglomeration in flour-water doughs and slurries have

not been fully understood. High molecular weight glute-

nins and glutenin macropolymer formed by the glutenin

particles have been shown in the last 10 years to add

strength (elasticity) to a wheat flour dough (Antes &

Wieser, 2001; Bekkers, Lichtendonk, Graveland, & Plij-ter, 2000; Don, Lichtendonk, Plijter, & Hamer, 2003a,

2003b; Schropp & Weiser, 1996; Singh & MacRitchie,

2001; Southan & MacRitchie, 1999; Uthayakumaran,

Stoddard, Gras, & Bekes, 2000; Veraverbeke, Verbrug-

gen, & Delcour, 1998; Wooding, Kavale, MacRitchie,

& Stoddard, 1999). However, the wet-processing quality

of a wheat flour and its relationship to flour protein

quality remain mostly unknown.Gluten proteins in the waxy wheat flours appeared to

be weaker than those of the controls as indicated by

their lower SDS sedimentation volumes and IPP con-

tents (Table 1) and shorter mixograph mixing times

and lower mixing tolerances (Fig. 1). The IPP contents

of flours were reported to correlate strongly with dough

mixing time and mixing tolerance (Bean et al., 1998).

Also, elevated insoluble pentosans of the waxy flours(Table 1) may be the reason for the loss of their

cohesiveness and elasticity during kneading. Pentosans

Fig. 1. Mixograms of flours from nonwaxy and partial waxy control wheats (top row) and waxy wheats (middle and bottom rows) at optimum water

absorption levels (protein contents of flours given in parenthesis on 14% mb).


(2–3%) of wheat flours (Hashimoto et al., 1987; Line-

back & Rasper, 1988) were reported to bind or hold 5-to 10-fold water by their mass (Bushuk, 1966; Courtin

& Delcour, 2002) and to increase the viscosity of the li-

quid phase during wet-milling. This in turn caused a

reduction in the sedimentation rate of small B-starch

granules in a centrifugal field, translating to a reduced

starch yield (Witt, 1997). Pentosans also interfered with

gluten formation and aggregation during dough mixing

through viscosity-related interference of pentosans ongluten aggregation (McCleary, 1986; Wang, Hamer,

Vliet, & Oudgenoeg, 2002), steric hindrance of gluten

aggregation due to formation of a pentosan network

during dough mixing (Rouau, El-Hayek, & Moreau,

1994; Labat, Rouau, & Morel, 2002; Weegels, Marseille,

& Voorpostel, 1991), and through direct interaction of

pentosans with glutenin particles during dough mixing

(Wang et al., 2002; Wang, 2003; Wang, Hamer, et al.,2003a; Wang, Oudgenoeg, Vliet, & Hamer, 2003b), all

of which are expected to affect the wet-milling properties

of flours. In waxy wheats, genetic backgrounds, not the

waxy trait per se, are more likely the cause of weak

glutens.

Other methods of wet-milling were reported to be less

dependent on agglomeration traits of gluten in a dough

(Sayaslan, 2004; Zwitserloot, 1989a, 1989b), and suchmethods may work better for the separation of vital glu-

ten and starch from flours with poor gluten strength/

elasticity. According to Zwitserloot (1989a), some weak

flour doughs that weaken excessively in the Martin pro-

cess can be wet-milled by the HD process. In that pro-

cess and possibly in the other dispersion processes

(Hydrocyclone and Alfa-Laval/Raisio), the sensitivity

to gluten agglomeration quality exhibited in the Martinprocess may be marginalized because density differences

of the flour components appear to be the primary sepa-

ration factor in those processes. Also, concentrating the

gluten proteins and removing the viscosity-building sol-uble pentosans early in the wet-milling steps through

centrifugation, which is practiced in the dispersion pro-

cesses, may facilitate the wet-milling of waxy wheat

flours. In fact, this approach proved to be viable for

the wet-milling of the waxy wheat flours that failed by

the DW method (see results in the DD&C method below).

As expected, the yields of dry gluten fractions were

closely associated with the protein contents of theirflours. With the exception of Wx-2 and Leona, the waxy

wheat flours mostly yielded more dry glutens than the

control flours, but their protein contents (purity) were

�7–20% lower (Table 2). This particular Leona waxy

wheat sample gave the least dry gluten because of its ex-

tremely low protein content (9.4%). A high-protein Leo-

na sample is likely to give improved gluten yield and

wet-milling quality. The difficulty encountered duringwashing the starch away from the gluten reduced the

purities of the waxy flour gluten fractions. The protein

contents of the glutens isolated in this work were all

>73%, meeting the minimum 73% protein (N · 5.7, db)required by the Codex Alimentarius of the Food and

Agriculture Organization (FAO, 2002). Commercial

glutens have been found to contain 73–80% protein on

dry solids basis (Miller & Hoseney, 1996). Dreese, Fau-bion, and Hoseney (1988) showed that starch accounted

for about 8% of the impurities in the glutens from differ-

ent flours.

As listed in Table 2, the starch recoveries from the

waxy wheat flours (�72–78%) were statistically similar

to the recoveries (�76–80%) from the control flours, ex-

cept for the reduced recovery (�68%) from Leona.

However, some of the waxy starches were contaminatedwith more proteins (0.4–0.5%) than the starches from

the controls (<0.3%). Granule size distributions were

Wx-A

0

2

4

6

8

10

12

804020105310

Vol

ume

(%)

Wx-B

0

2

4

6

8

10

12

804020105310

Vol

ume

(%)

Wx-C

0

2

4

6

8

10

12

804020105310

Vol

ume

(%)

Karl 92 (nonwaxy)

0

2

4

6

8

10

12

804020105310

Granule Size (µm) Granule Size (µm)

Granule Size (µm)Granule Size (µm) Granule Size (µm)

Ike (partialwaxy)

0

2

4

6

8

10

12

804020105310

Vol

ume

(%)

Vol

ume

(%)

Fig. 2. Typical bimodal size distributions of starch granules isolated from control wheats (top row) and several selected waxy wheats (bottom row).


determined for selected waxy starches (Fig. 2); as ex-

pected they showed a typical bimodal size distribution

with �25–30% by weight of the granules below 10 lm.In other words, granule size distributions of the waxy

and control starches isolated by the two methods of

wet-milling were comparable, which is consistent with

the results of Yoo and Jane (2002) and Abdel-Aal etal. (2002). The soluble flour solids varied from 5.8% to

9.9% in the waxy flours (Table 2), which is within the

range of 5–15% water-solubles found in wheat flours

(Hamer et al., 1989; Maijala, 1976; Witt, 1997). About

one-fifth of the flour weight for all the control and waxy

wheat flours was unaccounted for in the gluten, starch,

and water solubles fractions (Table 2). The unaccounted

solids for Leona flour were even higher (�29%).Those unaccounted solids were mostly in the tailings re-

moved during centrifugal purification of the starch

fractions.

3.4. Wet-milling properties of flours by dough-dispersion

and centrifugation (DD&C) method

Because of the difficulties encountered during thewet-milling of the waxy wheat flours by the DW method

as discussed above, which requires a strongly agglomer-

ated gluten in dough for efficient separation of the starch

and gluten fractions, the method described by Czucha-

jowska and Pomeranz (1993, 1995) was tested. In that

method, a stiff dough was mixed to optimum and rested

under �1 parts of water for 30 min. Then the dough wassheared with additional water in a blender to form a dis-persion. The dispersion is centrifuged to give mainly

three layers; a top supernatant, a middle protein-rich

layer, and a bottom layer of practically pure starch. It

appears that the gluten proteins were agglomerated,

mostly during dough mixing, and the protein strands

in the agglomerates were dislodged from starch granules

during high-shear dispersion step. During the centrifu-

gation, the dispersed gluten is thought to form a fine

mesh network which allows the passage of the rapidly

sedimenting large starch granules. After centrifugation,

the viscous supernatant containing the soluble pento-

sans and the sedimented starch layer (�50% of total

starch) was easily removed from the middle protein-richlayer. The middle layer in the centrifuged mixture was

sufficiently cohesive even at the beginning of kneading

so that the remaining starch was easily removed by

kneading and washing under water.

Leona waxy flour gave a similar wet-milling trend by

both the DW and DD&C methods; a lower quantity of

dry gluten, more protein in starch, and elevated water-

solubles (Tables 2 and 3) probably because of its lowprotein quantity and quality. However, when wet-milled

by the DD&C method, Leona waxy wheat gave even

lower dry gluten and protein recovery. The DD&C

method, as compared to the DW method, employed

more shear during the wet-processing, which was likely

to damage already weak gluten aggregates in Leona

sample. In contrast to the DW method, the separation

of starch and gluten fractions from all other waxy wheatflour doughs by the DD&C method was accomplished

with similar ease to that of the controls. In other words,

waxy flour doughs that failed for wet-milling in the ori-

ginal DW method could be wet-processed by the DD&C

method.

The waxy wheat flours wet-milled by the DD&C

method gave similar or elevated yields of gluten with re-

duced purities as compared to the control flours (Table3). Thus, both wet-milling methods gave reduced protein

levels in the gluten fractions from the waxy wheats.

However, the protein contamination in the waxy starch

fractions was almost cut in half to <0.3% by the DD&C

method of wet-milling (Table 3) compared to the DW

method (Table 2).

Table3

Wet-m

illingdata

forwheatfloursbydough-dispersionandcentrifugation(D

D&C)methodon100g(14%

mb)offlour

Floursample

Flour

Wetgluten

Dry

glutenfraction

Starchfraction

Solublea

solids(%

)

Unaccounteda

solids(%

)Proteinb

(N·5.7)

Yieldb(%

)Glutena

yield

(%)

Proteina

(N·5.7)(%

)

Protein

recovery(%

)

Starcha

yield

(%)

Proteina

(N·5.7)(%

)

Starch

recovery(%

)

Controlwhea

ts

Karl92(nonwaxy)

12.1

30.9

12.3

88.7

77.9

63.4

0.26

80.1

6.3

18.0

Ike(partialwaxy)

12.9

37.6

13.9

89.0

82.8

61.5

0.23

77.1

5.7

19.0

Waxy

whea

ts

Wx-A

12.0

39.3

13.9

80.5

79.9

55.3

0.23

75.1

10.1

20.8

Wx-B

12.0

43.4

16.2

72.2

84.0

57.0

0.15

76.3

8.4

18.4

Wx-C

13.1

43.6

16.1

80.0

84.4

56.9

0.19

74.3

7.7

19.3

Wx-1

14.2

52.9

18.2

80.4

88.6

57.7

0.26

80.1

9.7

14.5

Wx-2

10.9

30.3

11.9

83.8

78.5

59.8

0.16

79.6

9.0

19.3

Wx-3

13.6

41.6

16.0

85.7

86.9

54.5

0.22

73.0

11.0

18.5

Leona

9.4

11.0

3.7

79.6

27.1

56.0

0.37

72.4

11.2

29.1

Tukey�sHSD

(a=0.05)

–7.8

2.3

4.5

11.6

6.8

0.10

NSc

2.3

6.8

aDry

basis.

b14%

flourmoisture

basis.

cNosignificantdifference

ata=0.05(P

>0.05).


4. Conclusions

Waxy wheats gave reduced flour yields, and the flours

contained less starch but more crude fat and pentosans.

The gluten proteins of waxy wheats were weaker than

those of the nonwaxy and partial waxy control wheatsas indicated by their poor mixograms, decreased IPP

contents, and lower SDS sedimentation volumes. It is

more likely the genetic backgrounds of the waxy wheats,

not the waxy trait per se, are the causes of their weak

glutens. Some of the waxy flour doughs failed in the

wet-milling by the DW method as the DW method relies

heavily on the gluten aggregation traits of flours. It is

therefore recommended that wet-milling of the waxywheat flours with weak gluten be done by an aqueous

dispersion process that is less dependent on gluten

strength and less affected from the deleterious interfer-

ence of pentosans on gluten formation and aggregation.

In this regard, the DD&C aqueous dispersion method of

wet-milling used in this study facilitated the wet-milling

of the waxy flour doughs and gave �80% recovery of

flour protein in the gluten fraction with �80% protein,and �75% waxy starch recovery with <0.3% protein.

References

AACC (2000). Approved methods of the American association of cereal

chemists (10th ed.). St. Paul, MN: American Association of Cereal

Chemists.

Abdel-Aal, E. S., Hucl, P., Chibbar, R. N., Han, H. N., & Demeke, T.

(2002). Physicochemical and structural characteristics of flours and

starches from waxy and nonwaxy wheats. Cereal Chemistry, 79,

458–464.

Anderson, R. A. (1967). Manufacture of wheat starch. In R. L.

Whistler & E. F. Paschall (Eds.). Starch: Chemistry and technology

(Vol. II, pp. 53–63). New York: Academic Press.

Anderson, R. A. (1974). Wet-processing of wheat flour. In G. E.

Inglett (Ed.), Wheat: Production and utilization (pp. 355–365).

Westport, CT: AVI Publishing.

Antes, S., & Wieser, H. (2001). Effects of high molecular weight

glutenin subunits on rheological dough properties and breadmak-

ing quality of wheat. Cereal Chemistry, 78, 157–159.

Barr, D. J. (1989). The engineering of a modern wheat starch process.

In Y. Pomeranz (Ed.), Wheat is unique (pp. 501–508). St. Paul,

MN: American Association of Cereal Chemists.

Bean, S. R., Lyne, R. K., Tilley, K. A., Chung, O. K., & Lookhart, G.

L. (1998). A rapid method for quantitation of insoluble polymeric

proteins in flour. Cereal Chemistry, 75, 374–379.

Bekkers, A. C. A. P. A., Lichtendonk, W. J., Graveland, A., & Plijter,

J. J. (2000). Mixing of wheat flour dough as a function of the

physico-chemical properties of the SDS-gel proteins. In P. R.

Shewry & A. S. Tatham (Eds.), Wheat Gluten (pp. 408–412).

London: Royal Society of Chemistry.

Bergthaller, W. J. (1997). New uses of wheat gluten and non-starch

wheat components. In J. L. Steele & O. K. Chung (Eds.),

Proceedings of international wheat quality conference

(pp. 285–301). Manhattan, KS: Grain Industry Alliance.

Bergthaller, W., Lindhauer, M. G., & Zwingelberg, H. (1998). Variety

testing of wheat for starch production using small scale process. In

W. Praznik & A. Huber (Eds.), Contributions of the fourth


international workshop on carbohydrates as organic raw materials

(pp. 163–176). Vienna: WUV-Universitatsverlag.

Bhattacharya, M., Erazo-Castrejon, S. V., Doehlert, D. C., &

McMullen, M. S. (2002). Staling of bread as affected by waxy

wheat flour blends. Cereal Chemistry, 79, 178–182.

Bushuk, W. (1966). Distribution of water in dough and bread. Baker�sDigest, 40, 38–40.

Chakraborty, M., Matkovic, K., Grier, D. G., Jarabek, E. L.,

Berzonsky, W. A., McMullen, M. S., et al. (2004). Physicochem-

ical and functional properties of tetraploid and hexaploid waxy

wheat starch. Starch/Starke, 56, 339–347.

Chibbar, R. N., Baga, M., Demeke, T., & Hucl, P. (1997). Genetic

engineering for starch modification. In J. L. Steele & O. K. Chung

(Eds.), Proceedings of international wheat quality conference

(pp. 245–259). Manhattan, KS: Grain Industry Alliance.

Cornell, H. J., & Hoveling, A. W. (1998). Wheat chemistry and

utilization. Lancaster, PA: Technomic.

Courtin, C. M., & Delcour, J. A. (2002). Arabinoxylans and

endoxylanases in wheat flour bread-making. Journal of Cereal

Science, 35, 225–243.

Czuchajowska, Z., & Pomeranz, Y. (1993). Protein concentrate and

prime starch from wheat flours. Cereal Chemistry, 70, 701–706.

Czuchajowska, Z., & Pomeranz, Y. (1995). Process for fractionating

wheat flours to obtain protein concentrates and prime starch. U.S.

Patent, 5,439,526.

Dahlberg, B. I. (1978). A new process for the industrial production of

wheat starch and wheat gluten. Starch/Starke, 30, 8–12.

Don, C., Lichtendonk, W., Plijter, J. J., & Hamer, R. J. (2003a).

Glutenin macropolymer: A gel formed by glutenin particles.

Journal of Cereal Science, 37, 1–7.

Don, C., Lichtendonk, W. J., Plijter, J. J., & Hamer, R. J. (2003b).

Understanding the link between GMP and dough: From glutenin

particles in flour towards developed dough. Journal of Cereal

Science, 38, 157–165.

Douglas, S. G. (1981). A rapid method for the determination of

pentosans in wheat flour. Food Chemistry, 7, 139–145.

Dreese, P. C., Faubion, J. M., & Hoseney, R. C. (1988). Dynamic

rheological properties of flour, gluten, and gluten–starch doughs. I.

Temperature-dependent changes during heating. Cereal Chemistry,

65, 348–351.

FAO (2002). Codex standard for wheat gluten—163-1987. [http://

www.fao.org]. Rome, Italy: Food and Agriculture Organization.

Fellers, D. A. (1973). Fractionation of wheat into major components.

In Y. Pomeranz (Ed.), Industrial uses of cereals (pp. 207–228).

St. Paul, MN: American Association of Cereal Chemists.

Finney, K. F., & Shogren, M. D. (1972). A ten-gram mixograph for

determining and predicting functional properties of wheat flours.

Baker�s Digest, 46, 32–35, 38–42, 77.

Fujita, S., Yamamoto, H., Sugimoto, Y., Morita, N., & Yamamori,

M. (1998). Thermal and crystalline properties of waxy wheat

(Triticum aestivum L.) starch. Journal of Cereal Science, 27, 1–5.

Grace, G. (1988). Preparation of vital wheat gluten. In T. H.

Applewhite (Ed.), Proceedings of the world congress on vegetable

protein utilization in human foods and animal feedstuffs

(pp. 112–115). Champaign, IL: American Oil Chemists Society.

Grant, L. A., Viagnux, N., Doehlert, D. C., McMullen, M. S., Elias, E.

M., & Kianian, S. (2001). Starch characteristics of waxy and

nonwaxy tetraploid (Triticum turgidum L. var. durum) wheats.

Cereal Chemistry, 78, 590–595.

Graybosch, R. A. (1998). Waxy wheats: Origin, properties, and

prospects. Trends in Food Science and Technology, 9, 135–142.

Graybosch, R. A., Guo, G., & Shelton, D. R. (2000). Aberrant falling

numbers of waxy wheats independent of a-amylase activity. Cereal

Chemistry, 77, 1–3.

Graybosch, R. A., Peterson, C. J., Hansen, L. E., Rahman, S., Hill, A.,

& Skerritt, J. H. (1998). Identification and characterization of U.S.

wheats carrying null alleles at the wx loci. Cereal Chemistry, 75,

162–165.

Hamer, R. J., Weegels, P. L., Marseille, J. P., & Kelfkens, M. (1989). A

study of the factors affecting the separation of wheat flour into

starch and gluten. In Y. Pomeranz (Ed.), Wheat is unique

(pp. 467–477). St. Paul, MN: American Association of Cereal

Chemists.

Hashimoto, S., Shogren, M. D., & Pomeranz, Y. (1987). Cereal

pentosans: their estimation and significance. I. Pentosans in wheat

and milled wheat products. Cereal Chemistry, 64, 30–34.

Hayakawa, K., Tanaka, K., Nakamura, T., Endo, S., & Hoshino, T.

(1997). Quality characteristics of waxy hexaploid wheat (Triticum

aestivum L): Properties of starch gelatinization and retrogradation.


IWGA (1989). Wheat gluten––a natural protein for the future––today.

Prairie Village, KS: International Wheat Gluten Association.

Kerkkonen, H. K., Laine, K. M. J., Alanen, M. A., & Renner, H. V.

(1976). Method of separating gluten from wheat flour. U.S. Patent,

3,951,938.

Kim, W., Johnson, J. W., Graybosch, R. A., & Gaines, C. S. (2003).

Physicochemical properties and end-use quality of wheat starch as

a function of waxy protein alleles. Journal of Cereal Science, 37,

195–204.

Kiribuchi-Otobe, C., Nagamine, T., Yanagisawa, T., Ohnishi, M., &

Yamaguchi, I. (1997). Production of hexaploid wheats with waxy

endosperm character. Cereal Chemistry, 74, 72–74.

Labat, E., Rouau, X., & Morel, M. H. (2002). Effect of flour water-

extractable pentosans on molecular associations in gluten during

mixing. Lebensmittel-Wissenschaft und-Technologie (Food Science

and Technology), 35, 185–189.

Lineback, D. R., & Rasper, V. F. (1988). Wheat carbohydrates (3rd

ed.) In Y. Pomeranz (Ed.). Wheat chemistry and technology (Vol. I,

pp. 277–372). St. Paul, MN: American Association of Cereal

Chemists.

Lumdubwong, N., & Seib, P. A. (2001). Low- and medium-DE

maltodextrins from waxy wheat starch: Preparation and properties.

Starch/Starke, 53, 605–615.

Maijala, M. (1976). Environment and product gain in new wet wheat

process. Food Engineering, 48, 73–75.

Maningat, C. C., & Bassi, S. D. (1999). Wheat starch production. In

M. Tumbleson, P. Yang, & S. Eckhoff (Eds.), Proceedings of

international starch technology conference (pp. 26–40). Urbana, IL:

University of Illinois.

Maningat, C. C., & Seib, P. A. (1997). Update on wheat starch and its

use. In J. L. Steele & O. K. Chung (Eds.), Proceedings of

international wheat quality conference (pp. 261–284). Manhattan,

KS: Grain Industry Alliance.

Maningat, C. C., Bassi, S., & Hesser, J. M. (1994). Wheat gluten in

food and non-food systems. Technical Bulletin, XVI, 6. Manhattan,

KS: American Institute of Baking.

Maningat, C. C., DeMeritt, G. K., Chinnaswamy, R., & Bassi, S. D.

(1999). Properties and applications of texturized wheat gluten.

Cereal Foods World, 44, 650–655.

McCleary, B. V. (1986). Enzymatic modification of plant polysaccha-

rides. International Journal of Biological Macromolecules, 8,

433–436.

Meuser, F. (1994). Wheat utilization for the production of starch,

gluten and extruded products. In W. Bushuk & V. F. Rasper

(Eds.), Wheat: Production, properties and quality (pp. 179–204).

New York: Chapman & Hall.

Meuser, F., Althoff, F., & Huster, H. (1989). Developments in the

extraction of starch and gluten from wheat flour and wheat kernels.

In Y. Pomeranz (Ed.), Wheat is unique (pp. 479–499). St. Paul,


Miller, R. A., & Hoseney, R. C. (1996). Evaluating vital wheat gluten

quality. Cereal Foods World, 41, 412–416.

http://www.fao.org

http://www.fao.org


Morris, C. F., & Konzak, C. F. (2001). Registration of hard and soft

homozygous waxy wheat germplasm. Crop Science, 41, 934.

Morrison, W. R., Milligan, T. P., & Azudin, M. N. (1984). A

relationship between the amylose and lipid contents of starches

from diploid cereals. Journal of Cereal Science, 2, 257–271.

Nakamura, T., Yamamori, M., Hirano, H., Hidaka, S., & Nagamine,

T. (1995). Production of waxy (amylose-free) wheats. Molecular

and General Genetics, 248, 253–259.

Neel, D. V., & Hoseney, R. C. (1984). Factors affecting flowability of

hard and soft wheat flours. Cereal Chemistry, 61, 262–266.

Oleson, B. T. (1994). World wheat production, utilization, and trade.

In W. Bushuk & V. F. Rasper (Eds.), Wheat production, properties

and quality (pp. 1–11). New York: Chapman & Hall.

Posner, E. S., & Hibbs, A. N. (1997). Wheat flour milling. St. Paul,


Posner, E. S. (2000). Wheat. In K. Kulp & J. G. Ponte, Jr. (Eds.),

Handbook of cereal science and technology (2nd ed., pp. 1–30). New

York: Marcel Dekker.

Reddy, I., & Seib, P. A. (2000). Modified waxy wheat starch compared

to modified waxy corn starch. Journal of Cereal Science, 31, 25–39.

Rouau, X., El-Hayek, M. L., & Moreau, D. (1994). Effect of an

enzyme preparation containing pentosanases on the bread-making

quality of flours in relation to changes in pentosan properties.

Journal of Cereal Science, 19, 259–272.

Sasaki, T., Yasui, T., & Matsuki, J. (2000). Effect of amylose content

on gelatinization, retrogradation, and pasting properties of

starches from waxy and nonwaxy wheat and their F1 seeds. Cereal

Chemistry, 77, 58–63.

Sayaslan, A. (2004). Wet-milling of wheat flour: Industrial processes

and small-scale test methods. Lebensmittel-Wissenschaft und-Tech-

nologie (Food Science and Technology), 37, 499–515.

Schenck, F. W., & Hebeda, R. E. (1992). Starch hydrolysis products:

An introduction and history. In F. W. Schenck & R. E. Hebeda

(Eds.), Starch hydrolysis products (pp. 1–21). New York: VCH

Publishers.

Schropp, P., & Weiser, H. (1996). Effects of high molecular weight

subunits of glutenin on the rheological properties of wheat gluten.


Seib, P. A. (1994). Wheat starch: isolation, structure and properties.

Oyo Toshitsu Kagaki, 41, 49–69.

Seib, P. A. (1997). Wheat starch as a quality determinant. In J. L.

Steele & O. K. Chung (Eds.), Proceedings of international wheat

quality conference (pp. 61–82). Manhattan, KS: Grain Industry

Alliance.

Seib, P. A. (2000). Reduced-amylose wheats and Asian noodles. Cereal

Foods World, 45, 504–512.

Singh, H., & MacRitchie, F. (2001). Application of polymer science to

properties of gluten. Journal of Cereal Science, 33, 231–243.

Southan, M., & MacRitchie, F. (1999). Review: Molecular weight

distribution of wheat proteins. Cereal Chemistry, 76, 827–836.

USDA/NASS (2001). Agricultural statistics. U.S. Department of

Agriculture, National Agricultural Statistics Service. Washington,

DC: U.S. Government Printing Office.

Uthayakumaran, S., Stoddard, F. L., Gras, P. W., & Bekes, F. (2000).

Effects of incorporated glutenins on functional properties of wheat

dough. Cereal Chemistry, 77, 737–743.

Veraverbeke, W. S., Verbruggen, I. M., & Delcour, J. A. (1998). Effects

of increased high molecular weight glutenin subunits content of

flour on dough mixing behavior and breadmaking. Journal of

Agricultural and Food Chemistry, 46, 4830–4835.

Verberne, P., & Zwitserloot, W. (1978). A new hydrocyclone process

for the separation of starch and gluten from wheat flour. Starch/

Starke, 30, 337–338.

Verberne, P., Zwitserloot, W. R. M., & Nauta, R. R. (1979). Method

for separation of wheat gluten and wheat starch. U.S. Patent,

4,132,566.

Wang, M. (2003). Effect of pentosans on gluten formation and

properties. Ph.D. Dissertation. Wageningen: Wageningen

University.

Wang, M., Hamer, R. J., Vliet, T. V., & Oudgenoeg, G. (2002).

Interaction of water extractable pentosans with gluten protein:

effect on dough properties and gluten quality. Journal Cereal

Science, 36, 25–374.

Wang, M., Hamer, R. J., Vliet, T. V., Gruppen, H., Marseille, H., &

Weegels, P. L. (2003a). Effect of water unextractable solids on

gluten formation and properties: mechanistic considerations.

Journal Cereal Science, 37, 55–64.

Wang, M., Oudgenoeg, G., Vliet, T. V., & Hamer, R. J. (2003b).

Interaction of water unextractable solids with gluten protein: Effect

on dough properties and gluten quality. Journal Cereal Science, 38,

95–104.

Weegels, P. L., Marseille, J. P., & Hamer, R. J. (1988). Small scale

separation of wheat flour in starch and gluten. Starch/Starke, 40,

342–346.

Weegels, P. L., Marseille, J. P., & Voorpostel, A. M. B. (1991).

Enzymes as a processing aid in the separation of wheat into starch

and gluten. In W. Bushuk & R. Thackuk (Eds.), Gluten proteins

1990 (pp. 199–202). St. Paul, MN: American Association of Cereal

Chemists.

Witt, W. (1997). Modern method of separating the components of

wheat. In J. L. Steele & O. K. Chung (Eds.), Proceedings of

international wheat quality conference (pp. 231–248). Manhattan,

KS: Grain Industry Alliance.

Wooding, A. R., Kavale, S., MacRitchie, F., & Stoddard, F. L. (1999).

Link between mixing requirements and dough strength. Cereal

Chemistry, 76, 800–806.

Yamamori, M., & Quynh, N. T. (2000). Differential effects of Wx-A1,

-B1, and -D1 protein deficiencies on apparent amylase content and

starch pasting properties in common wheat. Theoretical and

Applied Genetics, 100, 32–38.

Yasui, T., Matsuki, J., Sasaki, T., & Yamamori, M. (1996). Amylose

and lipid content, amylopectin structure and gelatinization prop-

erties of waxy wheat (Triticum aestivum) starch. Journal of Cereal

Science, 24, 131–137.

Yasui, T., Sasaki, T., & Matsuki, J. (1999). Milling and flour pasting

properties of waxy endosperm mutant lines of bread wheat

(Triticum aestivum L). Journal of Science of Food and Agriculture,

79, 687–692.

Yasui, T., Sasaki, T., Matsuki, J., & Yamamori, M. (1997). Waxy

endosperm mutants of bread wheat (Triticum aestivum L.) and their

starch properties. Breeding Science, 47, 161–163.

Yoo, S.-H., & Jane, J.-L. (2002). Structural and physical characteristics

of waxy and other wheat starches. Carbohydrate Polymers, 49,

297–305.

Zwitserloot, W. R. M. (1989a). Production of wheat starch and gluten:

historical review and development into a new approach. In Y.

Pomeranz (Ed.), Wheat is unique (pp. 509–519). St. Paul, MN:

American Association of Cereal Chemists.

Zwitserloot, W. R. M. (1989b). New integrated process for starch,

gluten production. World Grain, 6, 12–15.

wet milling properties of waxy wheat flours by two laboratory methods

Documents