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Natural Food Flavors and ColorantsSecond Edition

Mathew Attokaran

This edition first published 2017© 2017 by John Wiley & Sons Ltd and the Institute of Food Technologists,

First Edition published in 2011

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Library of Congress Cataloging‐in‐Publication Data

Names: Attokaran, Mathew, author.Title: Natural food flavors and colorants / Mathew Attokaran.Description: 2nd edition. | Hoboken : Wiley-Blackwell, 2017. | Series: Institute of food

technologists series | Includes bibliographical references and index.Identifiers: LCCN 2016043324 (print) | LCCN 2016043737 (ebook) | ISBN 9781119114765

(hardback) | ISBN 9781119114772 (pdf) | ISBN 9781119114789 (epub)Subjects: LCSH: Flavoring essences. | Coloring matter in food. | Natural foods. |

BISAC: TECHNOLOGY & ENGINEERING / Food Science.Classification: LCC TP418 .A88 2017 (print) | LCC TP418 (ebook) | DDC 664/.5–dc23LC record available at https://lccn.loc.gov/2016043324

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v

About the Author viii

Preface ix

Acknowledgments xi

Part I General 1

Chapter 1. Analytical Considerations 3Chapter 2. Flavors 12Chapter 3. Spices 14Chapter 4. Essential Oils 17Chapter 5. Food Colors 20Chapter 6. Preparation of Plant Material for Extraction 23Chapter 7. Methods of Extraction of Essential Oils 26Chapter 8. Solvent Extraction 31Chapter 9. Supercritical Fluid Extraction 35Chapter 10. Homogenization of Extracts 37Chapter 11. Suspension in Solids 42Chapter 12. Deterioration during Storage and Processing 45

Part II Individual Flavors and Colorants 49

Chapter 13. Ajwain (Bishop’s Weed) 51Chapter 14. Allspice (Pimenta) 53Chapter 15. Aniseed 58Chapter 16. Anka Red Fungus 61Chapter 17. Annatto 63Chapter 18. Asafoetida 68Chapter 19. Basil 71Chapter 20. Bay Leaf (Laurel) 74Chapter 21. Beet Root 77Chapter 22. Bergamot Mint 80Chapter 23. Black Cumin 82Chapter 24. Black Pepper 85

Contents

vi Contents

Chapter 25. Capsicum 92Chapter 26. Caramel 100Chapter 27. Caraway 103Chapter 28. Cardamom 106Chapter 29. Carob Pod 112Chapter 30. Carrot 115Chapter 31. Cassia 119Chapter 32. Celery Seed 123Chapter 33. Chicory 128Chapter 34. Cinnamon 130Chapter 35. Cinnamon Leaf 133Chapter 36. Clove 136Chapter 37. Clove Leaf 141Chapter 38. Coca Leaf 143Chapter 39. Cochineal 145Chapter 40. Cocoa 149Chapter 41. Coffee 152Chapter 42. Colored Vegetables 156Chapter 43. Coriander 160Chapter 44. Coriander Leaf 163Chapter 45. Cumin 165Chapter 46. Curry Leaf 168Chapter 47. Date 172Chapter 48. Davana 175Chapter 49. Dill 180Chapter 50. Fennel 184Chapter 51. Fenugreek 188Chapter 52. Galangal: Greater 192Chapter 53. Galangal: Kaempferia 196Chapter 54. Galangal: Lesser 198Chapter 55. Garcinia Fruit 200Chapter 56. Garlic 204Chapter 57. Ginger 209Chapter 58. Grape 215Chapter 59. Grapefruit 219Chapter 60. Green Leaves 223Chapter 61. Hops 229Chapter 62. Hyssop 233Chapter 63. Japanese Mint 235Chapter 64. Juniper Berry 240Chapter 65. Kokam 244Chapter 66. Kola Nut 247Chapter 67. Large Cardamom 249Chapter 68. Lemon 251Chapter 69. Lemongrass 255Chapter 70. Licorice 259

Contents vii

Chapter 71. Lime 262Chapter 72. Long Pepper 266Chapter 73. Lovage 268Chapter 74. Mace 271Chapter 75. Mandarin 274Chapter 76. Marigold 277Chapter 77. Marjoram 282Chapter 78. Mustard 285Chapter 79. Nutmeg 289Chapter 80. Onion 294Chapter 81. Orange 298Chapter 82. Oregano 303Chapter 83. Paprika 305Chapter 84. Parsley 312Chapter 85. Peppermint 315Chapter 86. Red Sandalwood 318Chapter 87. Rosemary 321Chapter 88. Saffron 325Chapter 89. Sage 329Chapter 90. Savory (Sweet Summer) 332Chapter 91. Spearmint 334Chapter 92. Star Anise 337Chapter 93. Stevia 340Chapter 94. Sweet Flag (Calamus) 343Chapter 95. Tamarind 346Chapter 96. Tarragon 349Chapter 97. Tea 351Chapter 98. Thyme 354Chapter 99. Tomato 357Chapter 100. Turmeric 360Chapter 101. Vanilla 368

Part III Future Needs 375

Chapter 102. Opportunities with Natural Flavors 377Chapter 103. Opportunities with Natural Colorants 383

Index of Systematic Biological Names 388

Subject Index 390

viii

Mathew Attokaran (formerly A.G. Mathew) was born in Kerala State in India. He studied for his MSc in Oils, Fats, and Aromatics and was awarded his PhD in Food Chemistry. For over 28 years he carried out research on Food Science and Technology in the Central Food Technology Research Institute, Mysore, and National Institute for Interdisciplinary Science and Technology (CSIR), Trivandrum, before moving into industry. During his career he has guided PhD students and published over 200 scientific papers.

Many of Dr Attokaran’s research findings have been developed into viable technolo-gies, which have been effectively utilized in industry. His team developed the highly successful two‐stage process for preparing the spice oleoresin.

Twice he has been the leader of the Indian Delegation for the International Standards Organization (ISO) Committee meetings on Spices and Condiments held in Hungary (1983) and in France (1986) and was also the President of the Essential Oils Association of India for two terms. He has widely traveled in the United States, Europe, and Asia, visiting centers of research and industry as well as participating in numerous international conferences. Dr Attokaran has served on Short‐term Missions for three United Nations agencies: the Food and Agriculture Organization of the United Nations, Rome; the United Nations Industrial Development Organization, Vienna; and the International Trade Centre, of the United Nations and World Trade Organization, Geneva.

He is happily married and lives with his wife in Cochin, where he recently retired as the Technical Director of Plant Lipids Limited. He has two daughters and five grandchildren. Dr Attokaran can be reached at [email protected].

About the Author

mailto:[email protected].

ix

Ever since man began adding crushed roots, fruits, and leaves to food with a view to improving its organoleptic appeal, the search for more and more diverse flavors has continued. In addition, consumers want their food to be pleasing to the eye. It was soon evident that some plant materials gave a good color to the food. One of the distinctive features of humans that differentiates us from other animals is our innovative approach to improving the quality of our food. This enabled the production of such plant materials into ground, crushed, distilled, and extracted forms so as to obtain the flavor and color in convenient and effective forms, in order to be used as excellent natural additives.

With the development of modern chemistry, synthetic chemical molecules capable of producing delicious flavors and attractive colors started to emerge. But as man became more and more conscious of his own physiology and the interference of external molecules, leading to allergies, toxicity, and carcinogenicity, a decisive step back to natural substances was taken. After all, the human body is a biological engine and compatibility with bio‐derived materials is only natural.

A survey (Food Technology, IFT, 2010, April) of the top ten food trends reported that blending foods and drinks with naturally rich nutrients is the second most popular trend, and avoidance of chemical additives and artificial colors is the fifth most important trend that Americans now seek.

It was Ernest Guenther who pioneered the production of a six‐volume treatise, The Essential Oils, which covers the largest group of natural aroma and flavor materials used in food. Even after 60 years, the volumes are widely consulted by food scientists and technologists. Brian M. Lawrence continued the great tradition of reviews in the form of “Progress in Essential Oils,” which appears in the journal Perfumer and Flavorist. While the aroma‐contributing natural flavors of essential oils are well treated, the same cannot be said with regards to nonvolatile natural flavors.

There are many books on spices, but only a few deal with the chemical constituents that are referred to in this book. For spices and other materials, the compilation by Albert Y. Leung and Steven Foster, Encyclopedia of Common Natural Ingredients, is indeed a very valuable one. There are some good books and reviews on food colors. Nevertheless, the author believes that there is room for a book that includes all the available natural food flavors and colorants with adequate coverage of plant products, tips on extraction procedures, the chemistry of active principles, guidance on analytical methods, and links to regulatory bodies. This book is designed to assist people associated with food science, technology, and industry to realize the newfound dream of consumers for a return to natural substances that can be added to food to improve its appeal.

Preface

x Preface

Almost all the products dealt with in this book may indeed be familiar to ordinary people. However, their scientific significance, methods of production, and recognition in food laws are matters that laypeople will not be fully conversant with and will be a great help to students, researchers, and those in the industry.

The book is divided into three parts. Part I deals with matters connected with analysis, general properties, and techniques. Part II describes the various natural flavors and colorants that are available. Part III covers the future prospects that can be pursued by research workers and manufacturers.

Mathew Attokaran

xi

This book is the fulfillment of one of my cherished dreams. In making this publication available, it is my humble wish that it will serve food scientists, technologists, and industrialists the world over, to move towards flavors and colors of natural origin, a trend that is preferred by today’s consumers. However, this effort of mine would never have seen the light of day had it not been for the benevolent and generous support and encouragement I received from C.J. George, Managing Director of Plant Lipids Limited, a natural flavor and color producing company that is at the forefront of tech-nical excellence and quality management.

Furthermore, I am indebted to all staff members of Plant Lipids for their wonderful cooperation throughout this effort. In particular, may I express my gratitude to C.P. Benny, K.V. George, Thomas Mathew, and Binu V. Paul for useful discussions; John Nechupadom for his keen interest; Neelu Thomas for producing the figures; Moby Paul for assistance with the word processing; and the scientific staff for helpful hints. I must also acknowledge Professor Madhukar Rao for his valuable advice on the use of language.

I will be failing in my duty if I do not express my gratitude to Salim Pushpanath for the beautiful photographs. (All photographs copyright ©Salim Pushpanath.)

I am indeed grateful to the authorities of the Food Chemical Codex (FCC) for allowing me to quote the relevant descriptions of physical specifications of about 40 natural ingre-dients, most of which are essential oils. They are reprinted with permission, the United States Pharmacopeial Convention, copyright 2009, all rights reserved.

Last but not least, I thank the Institute of Food Technologists, USA, for the encour-agement and acceptance of my proposal for publication.

Mathew Attokaran

Acknowledgments for the Second Edition

I wish to thank profusely (Dr) Sreeraj Gopi, Sherin Mathew, Binu Paul, (Dr) L.P. Srikrishna, Robin George, and Mercy Thomas for valuable scientific inputs. I also thank Neelu Thomas for the digital structure of steviol and Moby Paul for the word processing.

Mathew Attokaran

Acknowledgments

Natural Food Flavors and Colorants, Second Edition. Mathew Attokaran. © 2017 John Wiley & Sons Ltd. Published 2017 by John Wiley & Sons Ltd.

1

Part IGeneral

Introduction

Before we discuss various flavors and colorants, numerous general aspects need to be understood. There are several eminent organizations, which, on a regular basis, review methods of determination, specifications, and safety assessments for flavors and colorants. The first part of this book deals with the techniques used and general characteristics of certain classes of flavors and colors that are necessary for a better understanding of the science and technology related to these components.

Various chapters cover subjects related to the analysis, extraction techniques, and modifications necessary for application in the area of foodstuffs. The general characteristics of some important classes of products, such as spices, essential oils, flavors, and colors, have also been given emphasis so as to assist researchers, manu-facturers, and formulators of foods.


3

The analysis of natural flavors and colorants involves three different types of determinations: (1) chemical analysis of constituents, (2) analysis of residues, and (3) microbiological analysis.

Chemical Analysis

The most important determinations are the contents of the active components. Some information on the determinations is included, where in addition to conventional anal-ysis, instrumental analysis may also be needed. For many of the components, estima-tions based on ultraviolet (UV) or visible spectrometric methods are appropriate. Furthermore, some volatile components can be determined by gas chromatography (GC) and nonvolatile components by high‐performance liquid chromatography (HPLC). An advanced method is GC‐MS where GC is combined with a mass spec-trometer (MS) to identify compounds separated by GC.

In the case of many substances containing volatile oils, such as spices, the moisture content cannot be determined by loss of weight. For example, the American Spice Trades Association, Inc. (ASTA) describes the toluene distillation method, where the volatile oil content can be determined by distillation using a Clevenger trap.

Official Methods of Analysis of AOAC International is a veritable bible as far as analysis of plant products is concerned. The US Food and Drug Administration (FDA) and the European Union (EU) provide the Code of Federal Regulations (CFR) and the European Food Safety Authority (EFSA), respectively, where regulatory, specifica-tion‐based, and analytical matters are described. Similarly, in the case of flavoring materials, the International Organization of the Flavor Industry (IOFI) provides some information. Codex Alimentarius also specifies and gives instructions for analysis. Good descriptions of a wide range of flavors, colorants, and test methods are given in the Food Chemicals Codex (FCC) (2008–2009).

Residue Analysis

In general, the residues that are unwelcome but likely to be present in natural flavors and colorants are: (1) solvents (in the case of extracts), (2) aflatoxins, (3) pesticides, and (4) heavy metals.

The residual solvent is limited according to food laws (see Chapter 8 on Solvent Extraction). This residue is determined by taking 50 g of the extract and collecting the residual solvent in 1 mL of toluene using water distillation under specified conditions.

1 Analytical Considerations

4 Natural Food Flavors and Colorants

The solvent present is then determined by GC. This is a method based on a paper by Todd (1960), on work carried out over half a century ago. Many attempts have been made to standardize an improved method but without success. Details of the determi-nation are given in the FCC.

Aflatoxins are produced by the fungus Aspergillus flavus (from which the name is derived) and a few members of Aspergillus and Penicillium species. EU limits are 5 ppb for B1 and 10 ppb for total aflatoxin content. The FDA limit is 20 ppb for total aflatoxins. Methods are available from the AOAC and ASTA (for spices only).

The EU has included limits on ochratoxin contamination. The recommended limit is 30 ppb. The AOAC has provided methods of analysis. Aflatoxins are determined using HPLC with a fluorescence detector.

For the analysis of pesticide residues, detailed methods are given in the Pesticide Analytical Manual published by the FDA. The AOAC is also a good reference source. The residues are divided into organochlorine, organophosphorus, and pyrethroids, and can be determined using GC. For organochlorine compounds and pyrethroids, an elec-tron capture detector (ECD) is required, while for organophosphorus compounds, a flame photometric detector (FPD) or nitrogen–phosphorus detector (NPD) is used.

Heavy metal residues, which are considered harmful and that are frequently found, include mercury, cadmium, arsenic, copper, lead, and zinc. Methods of testing are given by the AOAC. Atomic absorption spectrometry (AAS) is used for these determinations.

Artificial colors became the focus of attention when there was an attempt to adulter-ate red chili with Sudan dyes. However, this is not generally a problem with flavors and colorants, and its significance is gradually disappearing. For capsicum and turmeric, restrictions were introduced by the EU for the following dyes: butter yellow, fast garnet GBC, methyl yellow, metanil yellow, orange II, para red, p‐nitro‐analine, rhodamine, Sudan black B, Sudan orange, Sudan red B, Sudan red I to IV, and toluidine red. Bixin was also introduced more as a measure of preventing cross contamination.

The initial limit for these artificial dyes was 10 ppb, which means the analysis requires the use of LC‐MS‐MS, in which a liquid chromatograph (LC) is connected with two mass spectrometers to quantify low levels of the target compounds. Now the limit may be increased to 500 ppb, which can be determined by HPLC. Readers will do well to check whether the increase in the limit is effected.

There is a general feeling that adulteration at these levels is not an advantage that can be readily exploited. Furthermore, contamination can result from many other means. For example, pesticide manufacturers use colors such as rhodamine for color coding their products to assist farmers in their identification, lubricants for machines used in farming operations and grinding are sometimes color coded, and farmers use dyes to write details such as weight, date, and lot number on bags of products.

Instrumental Chemical Analysis

Today chemical analysis has progressed from the initial days of volumetric and gravimet-ric determinations to chemical instrumentation. Instrumental analysis is more precise, reliable, and easier to carry out for both chemical analysis of constituents and, particu-larly, residue analysis. Initially colorimetric methods became the most dominant tools.

Analytical Considerations 5

By taking advantage of the Beer–Lambert law of absorption, and comparing with a standard solution of known strength, the concentration of a chemical constituent can be determined at the absorption maxima in the visible region. Subsequently spectropho-tometry, wherein either UV or visible spectra can be used, has become the major instrumental method for determinations.

In recent years, chromatography has become the most powerful tool for the deter-mination of chemical compounds in plant products or extracts.

Gas Chromatography (GC)For volatile constituents, gas–liquid chromatography, or more often simply called gas chromatography, has become very valuable for separating and analyzing chemical constituents that can be transformed into a volatile gaseous phase through controlled heating. The specific compound is then separated from other constituents while pass-ing through a column. The mobile phase, which carries the volatile component through the column, is a carrier gas, usually an inert gas such as nitrogen or helium. The column is tubing made from glass, a polymer, or metal, which is coated with a stationary phase. The stationary phase is a microscopic layer of a suitable liquid or polymer on a nonreactive solid support. The volatile analyte of interest is then detected, using various types of detectors, depending on the class of compounds of interest.

Thermal Conductivity Detector (TCD) This is based on the change in thermal conductivity to the reference flow of a carrier gas as a result of the volatile compound. When the volatile compound emerges from the column, the thermal conductivity in the chamber, where one of the arms of a Wheatstone bridge is positioned, is reduced. This results in a detectable signal due to an upset in the electrical balance of the Wheatstone bridge.

Flame Ionization Detector (FID) The principle of an FID is based on the detec-tion of ions formed during the combustion of organic compounds in a hydrogen flame. The ions generated are proportional to the concentration of organic compounds in the gas stream. Hydrocarbons generally have molar response factors corresponding to the carbon atoms in their molecules, whereas oxygenated and other heteroatoms tend to have a lower response factor. FID cannot detect inorganic molecules. Because it oxi-dizes organic molecules, it is not useful in preparatory work.

Electron Capture Detector (ECD) This is a device for detecting electron‐absorbing components of high electronegativity, for example, halogenated com-pounds. It has a β‐particle (electron) emitter, in conjugation with a make‐up gas such as nitrogen flowing through the detection chamber. A typical electron emitter con-sists of a metal foil holding 10 μCi (370 MBq) of the radionuclide 63Ni. The electrons from the electron emitter collide with the make‐up gas molecules and move towards the positively charged anode, resulting in the production of a current. As the volatile compound is carried into the detector, electron‐absorbing molecules of the volatile compound under analysis capture electrons, resulting in a proportionate reduction in the current.


These detectors are very sensitive to halogenated compounds such as chlorinated pesticides.

Nitrogen–Phosphorus Detector (NPD) In this type of detector, thermal energy ionizes a volatile compound. Nitrogen and phosphorus can be selectively detected with a high degree of sensitivity, and therefore an NPD is useful for analyzing phos-phorus‐containing pesticides.

A concentration of hydrogen gas below the minimum required for ignition is employed. A rubidium or cesium bead ignites the hydrogen and forms a cold plasma. When excited by an alkali metal, ejection of electrons results, which are detected as a current flow between an anode and a cathode in the chamber. A nitrogen or phosphorus volatile leaving the chromatography column causes an increase in current, which can be detected.

Flame Photometric Detector (FPD) Phosphorus‐containing pesticides can also be determined using FPD. This allows sensitive and selective measurement of volatile sulfur and excited hydrogen phosphorus oxide species in a reducing flame. A photo-multiplier tube measures the chemiluminescent emissions from these species. By using an appropriate filter, the FPD can determine either sulfur (394 nm) or phospho-rus (526 nm).

High‐Performance Liquid Chromatography (HPLC) Originally known as high‐pressure liquid chromatography, HPLC is a technique to detect, quantify, and even identify nonvolatile components. Here the sample is dissolved in a suitable solvent and passed through a column packed with a stationary adsorbent material. Unlike in conventional column chromatography, where passage of the dissolved material through the adsorbent material occurs through the use of gravity, HPLC relies on pumps to pass a pressurized liquid solvent containing the sample mixture through long, thin columns filled with adsorbents. Each component of the sample moves at a different speed due to differences in the intensities of adsorption on the stationary phase. This results in separation of the components as they emerge from the column.

The active component of the stationary phase in the column is usually a granular material such as silica or a polymer, of 2–50 µm in size. The separated molecules leav-ing the column are detected by a suitable detector.

Typically, the columns were long and thin, of 4.5 mm diameter and 250 mm length. However, more recently, columns of 2.5 mm diameter and 50 mm length have been used. To increase the efficiency, sub‐2 µm diameter particles, compared with the con-ventional 5 µm, are being used as adsorbents. Since very high pressures are used to pass the solution through the column, this technique is often referred to as ultra high‐pressure liquid chromatography (UHPLC).

UV or UV/Visual Detector UV detectors, which are frequently used, use a deuterium discharge lamp with the wavelength ranging between 190 and 380 nm. When longer


wavelengths are required, an additional tungsten lamp (range 390–700 nm) is used. Combination detectors are currently available (photodiode array).

Almost all the chemical constituents that are analyzed may have absorptions in both ranges. It should be noted that not all components have similar spectra. The concentration may not be proportional to the peak size, as compounds with greater molar extinction coefficients can produce bigger peaks, even if present at a low dose.

Refractive Index Detector This can be considered as a universal detector for HPLC. The principle involved is the change in refractive index of the effluent when the compound under investigation passes the detector along with solvent. Naturally it is advantageous to have a large difference between the refractive index of the com-pounds and the mobile phase solvent.

Fluorescence Detector This is the most sensitive of all HPLC detectors. About 15% of all compounds fluoresce. Conjugated π‐electrons in aromatic compounds produce the highest fluorescence activity. Fluorescence sensitivity is usually 10–1000 times greater than for UV detectors, even for strong UV-absorbing compounds. Moreover, fluorescence detectors are selective and specific. When com-pounds have specific functional groups that are excited by shorter wavelengths but emit at higher wavelengths, they are credited with having fluorescence. Aflatoxins, which can be excited in this manner and produce fluorescence emissions, are detected using fluorescence detectors as they are required to be measured at the parts per billion level.

Mass spectrometer (Ms) This produces an ion signal as a function of the mass‐to‐charge ratio. In order to do this, mass spectrometry works by ionizing chemical compounds to generate charged molecular fragments. The spectra are useful for determining the elemental or isotopic character of the sample and for elucidating the chemical structure of the molecule.

The ionization is achieved by bombarding a solid, liquid, or gaseous sample with electrons. The ions that emerge are separated according to their mass‐to‐charge ratio. The ions are detected by an electron multiplier. The atoms or molecules in the sample are then identified by correlating known masses with the identified masses or through a character fragmentation pattern.

Chromatography Combined with Mass SpectrometryA development is combining GC or HPLC with MS, providing both mass resolving and mass determining capability. MS can not only detect, but also indicate the properties of the molecule, so much so it can even be useful in identification. Thus a complex mixture of volatile or nonvolatile compounds can be separated effectively by GC or HPLC, respectively, and the structure of individual components can be arrived at by comparing with the corresponding data for standard reference compounds. Thus in GC‐MS, a stream of separated compounds is fed into the ion source, which is a metallic filament to which a voltage is applied. The filament emits electrons,


which ionize the compounds that are being analyzed. The ions formed are further fragmented, yielding expected patterns of intact ions and fragments, which are passed on to the MS analyzer, resulting in the identification of the compounds.

However, in LC‐MS ions are generated either by the loss or by the gain of charge from a neutral species. Here the ionization is effected by electron spray ionization.

Both GC and LC can be connected to a system with two MS instruments work-ing in tandem to form GC‐MS‐MS or LC‐MS‐MS. Here the compounds are ionized in the first MS. The resulting chosen ion can be further fragmented by the second MS, resulting in daughter ions, which can be measured to quantify the original compound, even when present at very low levels of parts per billion or even parts per trillion.

Atomic Absorption Spectroscopy (AAS)This is very useful for determining the concentration of an element, as a spectroscopic analytical procedure using the absorption of element-specific optical radiation (light) by free atoms in the gaseous state is utilized.

Atomic absorption is so sensitive that it can measure concentrations with an accu-racy of parts per billion. The technique makes use of the wavelengths of light specifi-cally absorbed by the element in question. This corresponds to the energies needed to promote electrons from one energy level to a higher level.

AAS is particularly useful for determining the level of heavy metals in plant prod-ucts or their extracts. Besides food, it is also used in clinical, pharmaceutical, and environmental analysis.

Microbiological Analysis

For steam‐distilled essential oils and solvent‐extracted flavors and colorants, microbial contamination is not a major issue due to the sterilizing effect of processing. However, for plant products and aqueous extracts, microbial contamination is important. In ordi-nary cases where hygiene is well maintained, an evaluation of total plate count (TPC) or yeast and mold (Y&M) will suffice. However, in badly contaminated cases, the following pathogenic bacteria need to be tested for: coliforms, especially Escherichia coli; Salmonella; Staphylococcus aureus; and Bacillus cereus.

Analytical ProcedureTo check the microbiology of samples, often the TPC or the Y&M count will give a fair idea.

For TPC and Y&M, the sample is diluted from 10–1 to 10–6 fold with peptone water depending on the level of infection. With relatively infection‐free products, such as oleo-resins, essential oils, and freshly made hot extracts, a dilution of 10–1 to 10–2 may be ideal. For clean products, such as spices or well‐dried products, a dilution of 10–3 to 10–4 may be needed. For highly infected materials, a dilution of 10–5 to 10–6 would be a requirement.

When using TPC, 1 mL of the diluted solution is poured into a sterile petri plate containing 15 mL of melted plate count agar. It is then incubated at 35 ± 1 °C for 48 hours, at the end of which the number of colonies is determined.


For Y&M, 1 mL of the diluted solution is poured into a petri plate containing 15 mL of melted potato‐dextrose‐agar (PDA). In order to restrict the bacterial activity, a few drops of chlorophenicol (or tartaric acid solution) are added. This is to reduce the pH from 7–7.5 (ideal for bacterial growth) to 2.5–3.5 (suitable for yeast and mold). It is then incubated at 25 ± 1 °C for 5 days to determine the number of colonies. If there are only a few colonies, the incubation can be continued for up to 7 days before the counting of colonies is carried out.

Counting of colonies is best done using an Automatic Colony Counter. From the number of colonies counted, the actual TPC or Y&M can be determined by multiply-ing the number with the reciprocal of the dilution factor.

For pathogens, each determination requires a specific method. These can be obtained from the FDA‐BAM (Bacterial Analytical Manual) or from the AOAC.

Ready‐made petri films are available, which saves the process of preparing the agar or PDA plates. Rapid petri films, as compared with ordinary films, are also available. These contain growth‐promoting agents so that the time of incubation for both TPC and Y&M can be reduced to 24 hours. There are also rapid petri films available for specialized tests for pathogens. In these cases, the time of incubation can be reduced from 3–5 days to a mere 24 hours.

Automated testing devices, in particular to reduce the time taken for each test, are currently being developed. One such device is available to determine the degree of contamination in the case of a swab test. These hygiene meters depend on detecting adenosine triphosphate (ATP) molecules.

Important Agencies

The FCC has described a wide range of flavoring and coloring materials. The AOAC and ASTA (for spices only) have given analytical procedures for determining such components. Identification numbers of different natural flavorings and colorants have been given by the Flavor and Extract Manufacturers Association (FEMA) and the Chemical Abstracts Service (CAS). The EU allocates E‐numbers to various items after all aspects that make them safe for use have been examined. To date, they have covered food colors and a few other items. Spices and their active components are yet to be given numbers. The FDA gives specifications and CFR numbers. FEMA, CAS, and CFR numbers, and E‐numbers, whenever they are available, are given under each item.

The full names and addresses of each of these valuable agencies are given in the following:

American Spice Trade Association1101 17th Street, NW Suite 700Washington, DC 20036, USAOfficial Analytical Methods(for methods of analysis on spices)

ASTA


AOAC (Association of Official Agricultural Chemists) International2275 Research Blvd, Ste 300Rockville, MD 20850-3250, USA(for methods of analysis of plant products and impurities)

AOAC

Food Chemicals CodexLegal Department of United StatesPharmacopeial Convention12601 Twinbrook ParkwayRockville, MD 20852, USA(for specification and test methods)

FCC

European Union/European Food Safety AuthorityVia Carlo Magno 1A43126 Parma, Italy(for food regulation, standards, and award of E‐number)

EFSA

US Food and Drug Administration10903 New Hampshire AvenueSilver Spring, MD 20993, USA(for regulatory matters and standards)Code of Federal Regulations (CFR)

FDA

Codex AlimentariusSecretariatViale delle Terme di Caracalla00153 Rome, Italy(for food safety, standards, and related matters)

CODEX

International Organization of the Flavor IndustrySecretariat, 6 Avenue des Art1210, Brussels, Belgium(consisting of the national associations of flavor manufacturers from

several countries)

IOFI

Flavor and Extract Manufacturers Association1101 17th Street NW, Suite 700Washington, DC 20036, USA(generally recognized as safe [GRAS] list)

FEMA

Chemical Abstracts ServiceAmerican Chemical Society2540 Olentangy River RoadColumbus, OH 43202, USA

CAS

FCC (FCC 6 2008–2009) is a body that provides descriptions, specifications, and testing methods for a wide range of food additives, including natural flavors and color-ants. Today, the body has become an authority on food additives. It is operated by the US Pharmacopeial Convention (USP), and it is certain that the professionalism of the USP will also be extended to food chemicals.


The following are the abbreviations for units of measurements used:

% percentage°C degree Celsiusµg microgram (10−6 g)µm micrometer (10−6 m)g gramkg kilogram (1000 g)km kilometer (1000 m)L literm metermg milligram (10−3 g)mL milliliter (10−3 L)mm millimeter (10−3 m)mt metric tonne (1000 kg)ng nanogram (10−9 g)nm nanometer (10−9 m)ppb part per billionppm part per millionv/w volume/weight

References

FCC 6. 2008–2009. Food Chemicals Codex, 6th edn. Rockville, MD: United States Pharmacopeial Convention.

Todd, P.H. 1960. Estimation of residual solvents in spice oleoresin. Food Technol. 141, 301–308.


12

Sources of Natural Flavors

In today’s world, there is a pronounced preference for natural materials to be used in food. As chemistry has developed, a large array of wonderful chemicals has been synthesized. Thus, the chemist can create compounds that give aroma, taste, and color. However, as some chemicals, upon testing, were found to be toxic and carcinogenic, consumers of food have made a decisive retreat back to nature. Development of organic foods, opposition to genetically modified items, avoidance of unwanted resi-dues during processing, and strict limits for mycotoxins, pesticide residues, and heavy metals are all manifestations of man’s urge to get back to nature as far as food materials are concerned.

One of the largest groups of flavors is spices. Spices have been used in food for a very long time. They contain essential oils, which contribute toward a fine aroma. In addition, many of them have pungency or hotness, which gives piquancy to the food, and so man began to use spices to make bland food more attractive for consumption. Since spices are so important, Chapter 3 is devoted to them.

The only other major group that is valuable for flavoring through the fine aroma contributed by the essential oils contained in them is citrus fruits. The peel of various citrus fruits contains fine essential oils. These oils can be extracted from the cells with-out the need to resort to steam distillation. In fact, the peels are only valuable for the essential oils, as they do not contain any nonvolatile components that contribute toward flavor. Only in some rare cases is the whole peel used as a flavorant, such as in cakes, some pastries, and orange marmalade. Whole limes or lemons with peel are used in pickles, but in most other cases, the separated essential oil is used.

There are also flavoring materials whose attractiveness is due to the alkaloids and polyphenols present in them. However, unlike spices, these are not used as such in food, they are mainly used as extracts either in beverages or for mastication.

Perceptions of Flavor

Flavor is a combination of taste, odor, and mouthfeel. Sweet, sour, salty, and bitter were regarded as the true tastes. Now “umami,” the brothy, meaty, or savory taste of glutamates, is also included in the list. A true taste is felt at specialized nerve endings on the tongue.

Sugar and other sweeteners give sweetness, while a salty taste is provided by sodium chloride. Both of these categories play a vital role in food and its preparation. Sourness, caused by H+ ions of acids, is provided by products such as tamarind,

2 Flavors

Flavors 13

garcinia fruit, lime, lemon, tomato, citric acid, and vinegar. Bitterness, for example, in quinine, is generally appreciated at an appropriate level only along with other tastes. Alkaloids such as in cocoa and coffee, saponins in fenugreek, and burned sugar in caramel contribute to bitterness.

In addition to true tastes, there are other sensoric factors that do not require specialized nerve endings. They are felt all over the body, but when experienced in the mouth along with other factors, they are perceived as a desirable factor in some foods. Pungency, astringency, coolness, and warmth belong to this class. Chemicals such as capsaicin in red chili, piperine in black pepper, and gingerol in ginger cause pungency, which is essentially a pain reaction. Astringency is a touch feeling caused by poly-phenols such as in tea and coffee, which temporarily link to proteins in the mouth. It is somewhat similar to the tanning of leather. Coolness or warmth is an effect of temperature, for example the cool feeling of ice cream or the warmth of hot coffee, although some chemicals, such as menthol, also create a sense of coolness. Alkaloids in general affect the nervous system and cause a sensation that will modify the flavor that one feels.

Mouthfeel includes the texture of the food, such as hardness, toughness, tenderness, or crispness. Flavoring and color extract play a minor role in texture, as they are added at low levels.

Odors or smells are caused by volatile compounds in food. Such compounds are generally organic. When referring to a desirable odor in food, it is called aroma. There are two steps in the perception of a smell: when a volatile compound diffuses, the stimuli are captured by the receptors in the nose; these are then processed by a section of the brain responsible for olfaction.

The science of smell and its detection is much more complicated than the detection of taste. Over the years, many studies have been conducted. Molecules can be divided into various primary odors such as camphoraceous, pungent, ethereal, floral, pepper-minty, musky, and putrid, according to their molecular size and shape.

The overall feeling of taste, mouthfeel, and aroma defines the flavor of a food. All of the flavor ingredients described in this book contribute significantly toward taste and aroma. Nevertheless, however attractive the flavor is, the appearance (especially color) is very important. Attractive and appropriate colors improve the appreciation of flavor and satisfaction of eating (see Chapter 5 on Food Colors).


14

Spices are a vast reservoir of good flavors. Even in ancient times, Europe had already shown its acceptance of the appetizing flavors of spices. In the fifteenth century, many daring maritime expeditions were undertaken to reach the source of the spices of the Orient. The voyages of Columbus and Vasco da Gama are two examples. While Columbus stumbled upon the great continent of America, Vasco da Gama came around the Cape of Good Hope in South Africa and landed in Calicut, a thriving port in those days on the southwest coast of India. Earlier than this, Arab tradesmen had been doing business with the Middle East, the Mediterranean region, and European countries, mainly using land routes combined with sea voyages from southwest India and the East Indies. In the thirteenth century, Marco Polo experienced the attractions of spices from the Orient on his travels. But the successful landing of Vasco da Gama and his team in India meant the export of Asian spices to Europe became a thriving business.

Barring leafy spices, such as Mediterranean herbs and mint, most of the major spices require the warm humid weather conditions of the tropics to grow. Even in the case of chili, the hot variety needs warm weather, and only paprika, which is primarily used for color, is grown in colder weather conditions. To Asians, spices are indeed the soul of their food. In the Western world, they evoke dreams of tropical lands, exciting expeditions, and the rise and fall of empires.

Spices are produced from various parts of a plant. They can be fruits (cardamom, chili), berries (juniper, black pepper, pimenta), seeds (celery, cumin, fennel), kernels (nutmeg), aril (mace), flower parts (saffron, clove), bark (cassia, cinnamon), leaves (mint, marjoram, bay), rhizome (turmeric, ginger), or bulbs (garlic, onion).

For trading purposes, black pepper, chili, ginger, and turmeric are regarded as the major spices. Seed spices, tree spices, and others are minor spices. In India, because of the high volume of trade, it is general practice to treat cardamom as a major spice. However, it should be noted that many of the seed spices, such as coriander, cumin, anise, and celery, are really the fruits, which when dried are called seeds.

Spices, especially major spices, are, in general, used in savory foods. This is because of the high level of hotness they impart. Black pepper, capsicum, and ginger are called hot spices. However, many seed spices and herbs are used in sweet preparations, such as cardamom, mint, and cinnamon.

While almost all the spices are described in Part II, some general aspects need further consideration. In almost all spices except chili the aroma is contributed by the essential oils that are present. Many major spices and, in fact, all spices (barring herbal and some seed spices), have nonvolatile pungent constituents, which give piquancy to the food.

3 Spices

Spices 15

A few of them, such as paprika, turmeric, and saffron, give an attractive color to the food. The pungent and color‐contributing components as well as essential oils are discussed in the next section, for the relevant spices. However, essential oils have some common properties and therefore need further examination (see Chapter 4).

Spice Oils and Oleoresins

During World War II, soldiers and some civilians had to spend long periods of time in a totally alien world. It was therefore necessary to have convenient foods and additives that reflected their preferred flavors. This trend for convenience food grew after the war, and the development of standardized spice oils and oleoresins was the natural result of such a need.

As already indicated, spices have two main flavor attributes. The one that catches the immediate attention of a consumer is the spice aroma. This is contributed by the essential oil or spice oil, which is detected by the olfactory organ of the nose. Spice oils can be separated by steam distillation.

The other flavor attribute is the hot, pungent taste felt in the mouth while masticat-ing. Pungency is caused by chemicals that are nonvolatile. Spices also have color, although only some of them are considered to be attractive, as in the case of paprika and turmeric. The coloring components are also nonvolatile. If all the flavor attributes of aroma, taste, and color are required, only solvent‐extracted oleoresin will be a com-plete extractive. Even the volatile spice oils will be found in the extract.

Before the improved two‐stage method of preparation of oleoresin was introduced in India in the 1970s, oleoresins used to be produced in a single solvent extraction stage. However, there are drawbacks in that the quality of the oil is not as good because of interference from the solvent. During the removal of the solvent, some of the fine aroma can be lost.

In the two‐stage process, the first step is separation of the spice oil by steam distil-lation. The deoiled spice, after drying and lump breaking, is extracted using an appro-priate solvent for the nonvolatile fraction. The solvent chosen can be that which is most suitable for just the nonvolatile components, as the essential oil has already been recovered. The resin fraction, obtained after removal of the solvent, is blended with an adequate quantity of oil collected in the first stage to obtain the oleoresin.

The spice oils removed in the first stage are unaffected by solvent. Generally, the yield of the oil is so high that only about half the quantity need be used for blending with the resin extract. In fact, during steam distillation of the first stage, the oil can be collected as two fractions. The first fraction will be richer in the harsher smelling monoterpenes. The second fraction will be richer in sesquiterpenes and oxygenated compounds. This second fraction can be used as salable oil. The first fraction with its strong top note will be ideal for blending with the nonvolatile resin obtained in the second stage by solvent extraction. Due to the improved two‐stage process, production of quality spice oils became a part of the oleoresin industry, thus making the process more commercially viable.

Irradiation has been found to be a good method to control microbial load. However, due to consumer fear of nuclear handling, this process has not become as popular as it should be. When ground thyme, rosemary, and black pepper were treated with


different levels of λ‐irradiation, no deleterious effects were seen. No microbial load was noticeable when irradiation was carried out at 12 kGy. Irradiation generally decreased levels of monoterpenes and increased oxygenated compounds. These effects were lower in samples kept in a modified atmosphere. It was concluded that there is a need to irradiate under an oxygen‐free atmosphere to reduce quality deterio-ration (Kirkin et al., 2014).

Reference

Kirkin, C.; Mitrevsky, B.; Gunes, G.; and Marriot, P. J. 2014. Combined effects of gamma‐irradiation and modified atmosphere packaging on quality of some spices. Food Chem. 154, 255–261.

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