H.-D. Belitz : W. Grosch :P. SchieberleFood Chemistry4threvisedandextendededWith481Figures,923Formulasand634Tablespringer
H.-D. Belitz · W. Grosch · P. Schieberle Food Chemistry 4th revised and extended ed. With 481 Figures, 923 Formulas and 634 Tables 123
PrefacePrefacetotheFirstGermanEditionThe very rapid development of food chemistry and technology over the last twodecades, which is due to a remarkable increase in the analytical and manufacturingpossibilities, makes the complete lack of a comprehensive, teaching or referencetext particularly noticeable. It is hoped that this textbook of food chemistry willhelp to fill this gap.In writing this volume we were able to draw on our experiencefromthelectures which wehavegiven,covering various scientific subjects,overthe past fifteen years at the Technical University of MunichSince a separate treatment of the important food constituents (proteins, lipids, car-bohydrates, flavor compounds, etc.)and of the important food groups (milk, meat,eggs,cereals,fruits,vegetables,etc.)has proved successful in ourlectures,the subjectmatter is also organized in the same way in this book.Compounds which are found only in particular foods are discussed where theyplay a distinctive role while food additives and contaminants are treated in theirown chapters.The physical and chemical properties of the important constituentsoffoods arediscussedin detail wheretheseformthebasisforunderstanding ei-ther the reactions which occur,or can be expected to occur, during the production,processing, storage and handling of foods or the methods used in analyzing them.An attempthas alsobeenmadeto clarifytherelationshipbetweenthe structureandproperties at the level of individual food constituents and at the level of the wholefood systemThe book focuses on the chemistry of foodstuffs and does not consider nationalorinternational food regulations.Wehavealso omittedabroaderdiscussion ofaspects related to the nutritional value, the processing and the toxicology of foods.Allof thesearean essential part of thetraining ofafoodchemistbut, becauseof theextent of the subject matter and the consequent specialization,must todaybe thesubject of separate books.Nevertheless,for all importantfoods we have includedbrief discussions of manufacturing processes and their parameters since these areclosely related to the chemical reactions occurring in foods.Commodity and production data of importance to food chemists are mainly givenin tabular form.Each chapter includes some references which are not intendedto form an exhaustive list.No preference or judgement should be inferred from thechoice of references; they are given simply to encourage further reading.Additionalliteratureof a moregeneral natureisgiven attheend of thebook.Thisbookisprimarilyaimedbothatstudentsof food and general chemistrybutalsoatthosestudentsofotherdisciplineswhoarerequiredorchoosetostudyfoodchemistryasasupplementarysubject.Wealsohopethatthiscomprehensivetext
Preface Preface to the First German Edition The very rapid development of food chemistry and technology over the last two decades, which is due to a remarkable increase in the analytical and manufacturing possibilities, makes the complete lack of a comprehensive, teaching or reference text particularly noticeable. It is hoped that this textbook of food chemistry will help to fill this gap. In writing this volume we were able to draw on our experience from the lectures which we have given, covering various scientific subjects, over the past fifteen years at the Technical University of Munich. Since a separate treatment of the important food constituents (proteins, lipids, carbohydrates, flavor compounds, etc.) and of the important food groups (milk, meat, eggs, cereals, fruits, vegetables, etc.) has proved successful in our lectures, the subject matter is also organized in the same way in this book. Compounds which are found only in particular foods are discussed where they play a distinctive role while food additives and contaminants are treated in their own chapters. The physical and chemical properties of the important constituents of foods are discussed in detail where these form the basis for understanding either the reactions which occur, or can be expected to occur, during the production, processing, storage and handling of foods or the methods used in analyzing them. An attempt has also been made to clarify the relationship between the structure and properties at the level of individual food constituents and at the level of the whole food system. The book focuses on the chemistry of foodstuffs and does not consider national or international food regulations. We have also omitted a broader discussion of aspects related to the nutritional value, the processing and the toxicology of foods. All of these are an essential part of the training of a food chemist but, because of the extent of the subject matter and the consequent specialization, must today be the subject of separate books. Nevertheless, for all important foods we have included brief discussions of manufacturing processes and their parameters since these are closely related to the chemical reactions occurring in foods. Commodity and production data of importance to food chemists are mainly given in tabular form. Each chapter includes some references which are not intended to form an exhaustive list. No preference or judgement should be inferred from the choice of references; they are given simply to encourage further reading. Additional literature of a more general nature is given at the end of the book. This book is primarily aimed both at students of food and general chemistry but also at those students of other disciplines who are required or choose to study food chemistry as a supplementary subject. We also hope that this comprehensive text
viPrefacewillproveuseful tobothfoodchemists and chemists whohave completedtheirformal education.We thank sincerely Mrs. A. Modl (food chemist), Mrs. R. Berger, Mrs. I. Hofmeier,Mrs. E. Hortig, Mrs. F. Lynen and Mrs. K. Wuist for their help during the prepara-tion of the manuscript and its proofreading.We are very grateful to Springer Verlagfor theirconsideration ofour wishes and for the agreeable cooperation.Garching,H.-D.BelitzJuly 1982W.GroschPrefacetotheFourthEnglishEditionThe fourth edition of the“Food Chemistry"textbook is a translation of the sixthGerman edition of this textbook. It follows a general concept as detailed in thepreface to the first edition given below. All chapters have been carefully checkedand updated with respect to the latest developments, if required. Comprehensivechanges have been made in Chapters 9(Contaminants),18 (Phenolic Compounds),20(Alcoholic Beverages)and 21 (Tea, Cocoa).The following topics were newlyadded:the detection of BSE and D-amino acids..theformationand occurrenceofacrylamideandfuran,.compounds having a cooling effect,technologically important milk enzymes,the lipoproteins of egg yolk,+-the structure of the muscle and meat aging,food allergies,the baking process..the reactivity of oxygen species in foods,.phytosterols,+glycemic index,..thecomposition of aromaswasextended:odorants (pineapple,rawand cookedmutton, black tea, cocoa powder, whisky) and taste compounds (black tea,roasted cocoa, coffee drink).The production data for the year 2006 were taken from the FAO via Internet. Thevolumeofthebookwasnotchangedduringtherevision as someexistingchapterswereshortened.We are very grateful to Dr.Margaret Burghagen for translating the manuscript. Itwas our pleasureto collaboratewithher.We would also like to thank Prof. Dr. Jirgen Weder and Dr. Rolf Kieffer for severalvaluable recommendations.We are also grateful to Sabine Bijewitz and Rita Jaukerfor assistance in completing the manuscript,and Christel Hoffmann for help withthe literature and the index.Garching,W. GroschMai 2008PSchieberle
vi Preface will prove useful to both food chemists and chemists who have completed their formal education. We thank sincerely Mrs. A. Mödl (food chemist), Mrs. R. Berger, Mrs. I. Hofmeier, Mrs. E. Hortig, Mrs. F. Lynen and Mrs. K. Wüst for their help during the preparation of the manuscript and its proofreading. We are very grateful to Springer Verlag for their consideration of our wishes and for the agreeable cooperation. Garching, H.-D. Belitz July 1982 W. Grosch Preface to the Fourth English Edition The fourth edition of the “Food Chemistry” textbook is a translation of the sixth German edition of this textbook. It follows a general concept as detailed in the preface to the first edition given below. All chapters have been carefully checked and updated with respect to the latest developments, if required. Comprehensive changes have been made in Chapters 9 (Contaminants), 18 (Phenolic Compounds), 20 (Alcoholic Beverages) and 21 (Tea, Cocoa). The following topics were newly added: • the detection of BSE and D-amino acids, • the formation and occurrence of acrylamide and furan, • compounds having a cooling effect, • technologically important milk enzymes, • the lipoproteins of egg yolk, • the structure of the muscle and meat aging, • food allergies, • the baking process, • the reactivity of oxygen species in foods, • phytosterols, • glycemic index, • the composition of aromas was extended: odorants (pineapple, raw and cooked mutton, black tea, cocoa powder, whisky) and taste compounds (black tea, roasted cocoa, coffee drink). The production data for the year 2006 were taken from the FAO via Internet. The volume of the book was not changed during the revision as some existing chapters were shortened. We are very grateful to Dr. Margaret Burghagen for translating the manuscript. It was our pleasure to collaborate with her. We would also like to thank Prof. Dr. Jürgen Weder and Dr. Rolf Kieffer for several valuable recommendations. We are also grateful to Sabine Bijewitz and Rita Jauker for assistance in completing the manuscript, and Christel Hoffmann for help with the literature and the index. Garching, W. Grosch Mai 2008 P. Schieberle
Contents0WaterI-0.1Foreword0.2-Structure.0.2.1Water Molecule.0.2.22Liquid Water and Ice0.3Effect on Storage Life.0.3.1mWater Activity..0.3.25Water Activity as an Indicator0.3.35Phase Transition of Foods Containing Water0.3.46WLFEquation..0.3.57Conclusion..70.4References18Amino Acids,Peptides,Proteins1.18Foreword1.28Amino Acids1.2.18General Remarks....91.2.2Classification.Discoveryand Occurrence91.2.2.1Classification..91.2.2.2Discovery and Occurrence.121.2.3Physical Properties.121.2.3.1Dissociation..1.2.3.213Configuration and Optical Activity1.2.3.314Solubility .....1.2.3.415UV-Absorption1.2.416Chemical Reactions161.2.4.1Esterificationof Carboxyl Groups.1.2.4.216Reactions of Amino Groups...161.2.4.2.1Acylation.1.2.4.2.218AlkylationandArylation201.2.4.2.3Carbamoyl andThiocarbamoylDerivatives211.2.4.2.4Reactions with Carbonyl Compounds..221.2.4.3Reactions Involving Other Functional Groups .231.2.4.3.1Lysine.231.2.4.3.2Arginine231.2.4.3.3AsparticandGlutamicAcids241.2.4.3.4Serineand Threonine241.2.4.3.5Cysteine and Cystine241.2.4.3.6Methionine.241.2.4.3.7Tyrosine
Contents 0 Water . 1 0.1 Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0.2 Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0.2.1 Water Molecule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0.2.2 Liquid Water and Ice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 0.3 Effect on Storage Life . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 0.3.1 Water Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 0.3.2 Water Activity as an Indicator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 0.3.3 Phase Transition of Foods Containing Water . . . 5 0.3.4 WLF Equation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 0.3.5 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 0.4 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 1 Amino Acids, Peptides, Proteins . 8 1.1 Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 1.2 Amino Acids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 1.2.1 General Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 1.2.2 Classification, Discovery and Occurrence . . . . . . . . . . . . . . . . . . . 9 1.2.2.1 Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 1.2.2.2 Discovery and Occurrence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 1.2.3 Physical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 1.2.3.1 Dissociation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 1.2.3.2 Configuration and Optical Activity . . . . . . . . . . . . . . . . . . . . . . . . . 13 1.2.3.3 Solubility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 1.2.3.4 UV-Absorption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 1.2.4 Chemical Reactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 1.2.4.1 Esterification of Carboxyl Groups . . . . . . . . . . . . . . . . . . . . . . . . . . 16 1.2.4.2 Reactions of Amino Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 1.2.4.2.1 Acylation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 1.2.4.2.2 Alkylation and Arylation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 1.2.4.2.3 Carbamoyl and Thiocarbamoyl Derivatives . . . . . . . . . . . . . . . . . . 20 1.2.4.2.4 Reactions with Carbonyl Compounds . . . . . . . . . . . . . . . . . . . . . . . 21 1.2.4.3 Reactions Involving Other Functional Groups . . . . . . . . . . . . . . . . 22 1.2.4.3.1 Lysine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 1.2.4.3.2 Arginine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 1.2.4.3.3 Aspartic and Glutamic Acids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 1.2.4.3.4 Serine and Threonine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 1.2.4.3.5 Cysteine and Cystine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 1.2.4.3.6 Methionine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 1.2.4.3.7 Tyrosine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
viliContents251.2.4.4Reactions of Amino Acids at HigherTemperatures251.2.4.4.1Acrylamide261.2.4.4.2Mutagenic Heterocyclic Compounds1.2.5Synthetic Amino Acids Utilized for Increasing29theBiological Value of Food (Food Fortification)321.2.5.1Glutamic Acid..321.2.5.2Aspartic Acid...321.2.5.3Lysine......331.2.5.4Methionine..331.2.5.5Phenylalanine331.2.5.6Threonine........331.2.5.7Tryptophan...341.2.6SensoryProperties1.334Peptides ....341.3.1General Remarks, Nomenclature.361.3.2Physical Properties361.3.2.1Dissociation.....361.3.3Sensory PropertiesS.......1.3.438Individual Peptides..381.3.4.1Glutathione1.3.4.239Carnosine, Anserine and Balenine391.3.4.3Nisin....1.3.4.440Lysine Peptides1.3.4.540Other Peptides ..1.440Proteins1.4.141AminoAcidSequence411.4.1.1AminoAcid Composition,Subunits421.4.1.2Terminal Groups431.4.1.3Partial Hydrolysis441.4.1.4Sequence Analysis1.4.1.5Derivationof AminoAcid Sequence46from the Nucleotide Sequence of theCoding Gene1.4.248Conformation1.4.2.148Extended Peptide Chains491.4.2.2Secondary Structure (Regular Structural Elements)501.4.2.2.1B-Sheet..511.4.2.2.2Helical Structures521.4.2.2.3ReverseTurns521.4.2.2.4Super-Secondary Structures1.4.2.353Tertiary and Quaternary Structures....531.4.2.3.1Fibrous Proteins-531.4.2.3.2Globular Proteins...551.4.2.3.3BSE++..+++.561.4.2.3.4Quaternary Structures..561.4.2.4Denaturation ......581.4.3Physical Properties...581.4.3.1Dissociation.601.4.3.2Optical Activity...1.4.3.360Solubility,Hydration and SwellingPower..621.4.3.4FoamFormationandFoamStabilization-1.4.3.562Gel Formation
viii Contents 1.2.4.4 Reactions of Amino Acids at Higher Temperatures . . . . . . . . . . . 25 1.2.4.4.1 Acrylamide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 1.2.4.4.2 Mutagenic Heterocyclic Compounds . . . . . . . . . . . . . . . . . . . . . . . 26 1.2.5 Synthetic Amino Acids Utilized for Increasing the Biological Value of Food (Food Fortification) . . . . . . . . . . . . . 29 1.2.5.1 Glutamic Acid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 1.2.5.2 Aspartic Acid. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 1.2.5.3 Lysine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 1.2.5.4 Methionine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 1.2.5.5 Phenylalanine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 1.2.5.6 Threonine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 1.2.5.7 Tryptophan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 1.2.6 Sensory Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 1.3 Peptides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 1.3.1 General Remarks, Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 1.3.2 Physical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 1.3.2.1 Dissociation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 1.3.3 Sensory Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 1.3.4 Individual Peptides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 1.3.4.1 Glutathione . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 1.3.4.2 Carnosine, Anserine and Balenine . . . . . . . . . . . . . . . . . . . . . . . . . 39 1.3.4.3 Nisin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 1.3.4.4 Lysine Peptides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 1.3.4.5 Other Peptides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 1.4 Proteins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 1.4.1 Amino Acid Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 1.4.1.1 Amino Acid Composition, Subunits . . . . . . . . . . . . . . . . . . . . . . . . 41 1.4.1.2 Terminal Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 1.4.1.3 Partial Hydrolysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 1.4.1.4 Sequence Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 1.4.1.5 Derivation of Amino Acid Sequence from the Nucleotide Sequence of the Coding Gene . . . . . . . . . . . 46 1.4.2 Conformation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 1.4.2.1 Extended Peptide Chains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 1.4.2.2 Secondary Structure (Regular Structural Elements) . . . . . . . . . . . 49 1.4.2.2.1 β-Sheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 1.4.2.2.2 Helical Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 1.4.2.2.3 Reverse Turns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 1.4.2.2.4 Super-Secondary Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 1.4.2.3 Tertiary and Quaternary Structures . . . . . . . . . . . . . . . . . . . . . . . . . 53 1.4.2.3.1 Fibrous Proteins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 1.4.2.3.2 Globular Proteins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53 1.4.2.3.3 BSE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 1.4.2.3.4 Quaternary Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 1.4.2.4 Denaturation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 1.4.3 Physical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 1.4.3.1 Dissociation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 1.4.3.2 Optical Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 1.4.3.3 Solubility, Hydration and Swelling Power . . . . . . . . . . . . . . . . . . . 60 1.4.3.4 Foam Formation and Foam Stabilization . . . . . . . . . . . . . . . . . . . . 62 1.4.3.5 Gel Formation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62