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
ixContents631.4.3.6Emulsifying Effect1.4.464Chemical Reactions641.4.4.1Lysine Residue...641.4.4.1.1Reactions Which Retain the Positive Charge651.4.4.1.2Reactions Resulting in a Loss of Positive Charge1.4.4.1.365Reactions Resulting in a Negative Charge661.4.4.1.4Reversible Reactions....1.4.4.266Arginine Residue....671.4.4.3Glutamic and Aspartic Acid Residues1.4.4.467CystineResidue(cf.also Section 1.2.4.3.5)1.4.4.568CysteineResidue (cf.alsoSection 1.2.4.3.5).691.4.4.6Methionine Residue691.4.4.7Histidine Residue ...701.4.4.8Tryptophan Residue1.4.4.970Tyrosine Residue ..701.4.4.10BifunctionalReagents701.4.4.11Reactions Involved in Food Processing1.4.574Enzyme-Catalyzed Reactions.741.4.5.1Foreword1.4.5.274Proteolytic Enzymes.1.4.5.2.174Serine Endopeptidases.1.4.5.2.276Cysteine Endopeptidases1.4.5.2.376Metalo Peptidases ..761.4.5.2.4Aspartic Endopeptidases1.4.6ChemicalandEnzymaticReactions79of InteresttoFoodProcessing...791.4.6.1Foreword801.4.6.2Chemical Modification.801.4.6.2.1Acylation .1.4.6.2.282Alkylation821.4.6.2.3Redox Reactions Involving Cysteine and Cystine831.4.6.3EnzymaticModification831.4.6.3.1Dephosphorylation831.4.6.3.2Plastein Reaction..861.4.6.3.3Cross-Linking.1.4.787Texturized Proteins871.4.7.1Foreword..1.4.7.288Starting Material ..881.4.7.3Texturization...881.4.7.3.1Spin Process1.4.7.3.289ExtrusionProcess1.589References2Enzymes932.1Foreword932.293General Remarks, Isolation and Nomenclature ....2.2.193Catalysis...2.2.294Specificity942.2.2.1Substrate Specificity2.2.2.295Reaction Specificity2.2.395Structure
Contents ix 1.4.3.6 Emulsifying Effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 1.4.4 Chemical Reactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 1.4.4.1 Lysine Residue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 1.4.4.1.1 Reactions Which Retain the Positive Charge . . . . . . . . . . . . . . . . . 64 1.4.4.1.2 Reactions Resulting in a Loss of Positive Charge . . . . . . . . . . . . . 65 1.4.4.1.3 Reactions Resulting in a Negative Charge . . . . . . . . . . . . . . . . . . . 65 1.4.4.1.4 Reversible Reactions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 1.4.4.2 Arginine Residue. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 1.4.4.3 Glutamic and Aspartic Acid Residues . . . . . . . . . . . . . . . . . . . . . . 67 1.4.4.4 Cystine Residue (cf. also Section 1.2.4.3.5) . . . . . . . . . . . . . . . . . . 67 1.4.4.5 Cysteine Residue (cf. also Section 1.2.4.3.5) . . . . . . . . . . . . . . . . . 68 1.4.4.6 Methionine Residue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 1.4.4.7 Histidine Residue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 1.4.4.8 Tryptophan Residue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 1.4.4.9 Tyrosine Residue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 1.4.4.10 Bifunctional Reagents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 1.4.4.11 Reactions Involved in Food Processing . . . . . . . . . . . . . . . . . . . . . 70 1.4.5 Enzyme-Catalyzed Reactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 1.4.5.1 Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 1.4.5.2 Proteolytic Enzymes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 1.4.5.2.1 Serine Endopeptidases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 1.4.5.2.2 Cysteine Endopeptidases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 1.4.5.2.3 Metalo Peptidases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 1.4.5.2.4 Aspartic Endopeptidases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 1.4.6 Chemical and Enzymatic Reactions of Interest to Food Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 1.4.6.1 Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 1.4.6.2 Chemical Modification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 1.4.6.2.1 Acylation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 1.4.6.2.2 Alkylation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 1.4.6.2.3 Redox Reactions Involving Cysteine and Cystine . . . . . . . . . . . . . 82 1.4.6.3 Enzymatic Modification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 1.4.6.3.1 Dephosphorylation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 1.4.6.3.2 Plastein Reaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 1.4.6.3.3 Cross-Linking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86 1.4.7 Texturized Proteins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 1.4.7.1 Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 1.4.7.2 Starting Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 1.4.7.3 Texturization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 1.4.7.3.1 Spin Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 1.4.7.3.2 Extrusion Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 1.5 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 2 Enzymes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 2.1 Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 2.2 General Remarks, Isolation and Nomenclature . . . . . . . . . . . . . . . 93 2.2.1 Catalysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 2.2.2 Specificity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 2.2.2.1 Substrate Specificity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 2.2.2.2 Reaction Specificity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 2.2.3 Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
xContents2.2.496Isolation and Purification2.2.597MultipleForms of Enzymes......972.2.6Nomenclature..2.2.798Activity Units.2.398EnzymeCofactors2.3.199Cosubstrates.2.3.1.199NicotinamideAdenineDinucleotide2.3.1.2102Adenosine Triphosphate2.3.2102Prosthetic Groups2.3.2.1102Flavins++++++2.3.2.2103Hemin..........2.3.2.3103Pyridoxal Phosphate .2.3.3104Metal Ions....2.3.3.1104Magnesium, Calcium and Zinc2.3.3.2105Iron,Copper and Molybdenum2.4106Theoryof EnzymeCatalysis2.4.1Active Site.......1062.4.1.1107Active Site Localization ..-2.4.1.2108Substrate Binding.2.4.1.2.1108Stereospecificity2.4.1.2.2109"Lock and Key" Hypothesis.2.4.1.2.3109Induced-fit Model ..2.4.2110Reasons for Catalytic Activity...2.4.2.1111StericEffects-OrientationEffects2.4.2.2112Structural Complementarity toTransition State1122.4.2.3EntropyEffect.2.4.2.4113General Acid-Base Catalysis.2.4.2.5114Covalent Catalysis.2.4.3.117Closing Remarks :2.5.117Kineticsof Enzyme-CatalyzedReactions2.5.1117EffectofSubstrateConcentration1172.5.1.1Single-Substrate Reactions1172.5.1.1.1Michaelis-Menten Equation2.5.1.1.2120Determination of Km and V.2.5.1.2121Two-SubstrateReactions2.5.1.2.1121Order of Substrate Binding2.5.1.2.2122RateEquationsforaTwo-SubstrateReaction2.5.1.3123Allosteric Enzymes..2.5.2125Effect of Inhibitors2.5.2.1126Irreversible Inhibition ....2.5.2.2126Reversible Inhibition...2.5.2.2.1126Competitive Inhibition2.5.2.2.2127Non-Competitive Inhibition.1282.5.2.2.3Uncompetitive Inhibition ..2.5.3...128Effect of pH on Enzyme Activity2.5.4130Influence of Temperature..2.5.4.1131TimeDependenceof Effects1312.5.4.2TemperatureDependenceofEffects2.5.4.3133Temperature Optimum.2.5.4.4134Thermal Stability2.5.5136InfluenceofPressure
x Contents 2.2.4 Isolation and Purification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 2.2.5 Multiple Forms of Enzymes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 2.2.6 Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 2.2.7 Activity Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 2.3 Enzyme Cofactors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 2.3.1 Cosubstrates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 2.3.1.1 Nicotinamide Adenine Dinucleotide . . . . . . . . . . . . . . . . . . . . . . . . 99 2.3.1.2 Adenosine Triphosphate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 2.3.2 Prosthetic Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 2.3.2.1 Flavins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 2.3.2.2 Hemin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 2.3.2.3 Pyridoxal Phosphate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 2.3.3 Metal Ions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 2.3.3.1 Magnesium, Calcium and Zinc . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 2.3.3.2 Iron, Copper and Molybdenum . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105 2.4 Theory of Enzyme Catalysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 2.4.1 Active Site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 2.4.1.1 Active Site Localization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 2.4.1.2 Substrate Binding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 2.4.1.2.1 Stereospecificity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108 2.4.1.2.2 “Lock and Key” Hypothesis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 2.4.1.2.3 Induced-fit Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 2.4.2 Reasons for Catalytic Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 2.4.2.1 Steric Effects – Orientation Effects . . . . . . . . . . . . . . . . . . . . . . . . . 111 2.4.2.2 Structural Complementarity to Transition State . . . . . . . . . . . . . . . 112 2.4.2.3 Entropy Effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 2.4.2.4 General Acid–Base Catalysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113 2.4.2.5 Covalent Catalysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114 2.4.3 Closing Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117 2.5 Kinetics of Enzyme-Catalyzed Reactions . . . . . . . . . . . . . . . . . . . 117 2.5.1 Effect of Substrate Concentration . . . . . . . . . . . . . . . . . . . . . . . . . . 117 2.5.1.1 Single-Substrate Reactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117 2.5.1.1.1 Michaelis–Menten Equation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117 2.5.1.1.2 Determination of Km and V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 2.5.1.2 Two-Substrate Reactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 2.5.1.2.1 Order of Substrate Binding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 2.5.1.2.2 Rate Equations for a Two-Substrate Reaction . . . . . . . . . . . . . . . . 122 2.5.1.3 Allosteric Enzymes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 2.5.2 Effect of Inhibitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 2.5.2.1 Irreversible Inhibition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 2.5.2.2 Reversible Inhibition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 2.5.2.2.1 Competitive Inhibition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 2.5.2.2.2 Non-Competitive Inhibition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 2.5.2.2.3 Uncompetitive Inhibition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128 2.5.3 Effect of pH on Enzyme Activity . . . . . . . . . . . . . . . . . . . . . . . . . . 128 2.5.4 Influence of Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 2.5.4.1 Time Dependence of Effects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131 2.5.4.2 Temperature Dependence of Effects . . . . . . . . . . . . . . . . . . . . . . . . 131 2.5.4.3 Temperature Optimum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 2.5.4.4 Thermal Stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134 2.5.5 Influence of Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
xiContents2.5.6137Influence of Water..2.6137Enzymatic Analysis2.6.1138Substrate Determination.2.6.1.1138Principles..2.6.1.2138End-Point Method.2.6.1.3140Kinetic Method2.6.2140Determination of EnzymeActivity2.6.3141Enzyme Immunoassay2.6.4142Polymerase Chain Reaction2.6.4.1143Principle of PCR ....2.6.4.2144Examples2.6.4.2.1144Addition of Soybean..1442.6.4.2.2Genetically Modified Soybeans..1442.6.4.2.3GeneticallyModifiedTomatoes.2.6.4.2.4.144Species Differentiation...2.7..144Enzyme Utilization in theFood Industry2.7.1145Technical Enzyme Preparations..2.7.1.1145Production ..............2.7.1.2145Immobilized Enzymes2.7.1.2.1145BoundEnzymes2.7.1.2.2145Enzyme Entrapment2.7.1.2.3.148Cross-Linked Enzymes2.7.1.2.4.148Properties..........2.7.2149Individual Enzymes2.7.2.1149Oxidoreductases...1492.7.2.1.1GlucoseOxidase.1492.7.2.1.2Catalase2.7.2.1.3149Lipoxygenase. 1492.7.2.1.4Aldehyde Dehydrogenase.1492.7.2.1.5Butanediol Dehydrogenase2.7.2.2**.150Hydrolases2.7.2.2.1*150Peptidases2.7.2.2.2150α-and β-Amylases ...2.7.2.2.3151Glucan-1,4-α-D-Glucosidase (Glucoamylase)2.7.2.2.4152Pullulanase(Isoamylase)..2.7.2.2.5152Endo-1,3(4)-β-D-Glucanase.2.7.2.2.6152α-D-Galactosidase..2.7.2.2.7152β-D-Galactosidase (Lactase)1522.7.2.2.8β-D-Fructofuranosidase (Invertase)1532.7.2.2.9α-L-Rhamnosidase..1532.7.2.2.10CellulasesandHemicellulases1532.7.2.2.11Lysozyme.2.7.2.2.12+153Thioglucosidase.1532.7.2.2.13Pectolytic Enzymes2.7.2.2.14....154Lipases....2.7.2.2.15Tannases..+*. 1542.7.2.2.16154Glutaminase2.7.2.3154Isomerases2.7.2.4154Transferases..2.8155References
Contents xi 2.5.6 Influence of Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137 2.6 Enzymatic Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137 2.6.1 Substrate Determination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138 2.6.1.1 Principles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138 2.6.1.2 End-Point Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138 2.6.1.3 Kinetic Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 2.6.2 Determination of Enzyme Activity . . . . . . . . . . . . . . . . . . . . . . . . . 140 2.6.3 Enzyme Immunoassay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141 2.6.4 Polymerase Chain Reaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142 2.6.4.1 Principle of PCR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 2.6.4.2 Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144 2.6.4.2.1 Addition of Soybean . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144 2.6.4.2.2 Genetically Modified Soybeans . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144 2.6.4.2.3 Genetically Modified Tomatoes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144 2.6.4.2.4 Species Differentiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144 2.7 Enzyme Utilization in the Food Industry . . . . . . . . . . . . . . . . . . . . 144 2.7.1 Technical Enzyme Preparations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145 2.7.1.1 Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145 2.7.1.2 Immobilized Enzymes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145 2.7.1.2.1 Bound Enzymes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145 2.7.1.2.2 Enzyme Entrapment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145 2.7.1.2.3 Cross-Linked Enzymes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148 2.7.1.2.4 Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148 2.7.2 Individual Enzymes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149 2.7.2.1 Oxidoreductases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149 2.7.2.1.1 Glucose Oxidase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149 2.7.2.1.2 Catalase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149 2.7.2.1.3 Lipoxygenase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149 2.7.2.1.4 Aldehyde Dehydrogenase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149 2.7.2.1.5 Butanediol Dehydrogenase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149 2.7.2.2 Hydrolases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 2.7.2.2.1 Peptidases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 2.7.2.2.2 α- and β-Amylases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 2.7.2.2.3 Glucan-1,4-α-D-Glucosidase (Glucoamylase) . . . . . . . . . . . . . . . . 151 2.7.2.2.4 Pullulanase (Isoamylase) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152 2.7.2.2.5 Endo-1,3(4)-β-D-Glucanase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152 2.7.2.2.6 α-D-Galactosidase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152 2.7.2.2.7 β-D-Galactosidase (Lactase) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152 2.7.2.2.8 β-D-Fructofuranosidase (Invertase) . . . . . . . . . . . . . . . . . . . . . . . . . 152 2.7.2.2.9 α-L-Rhamnosidase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153 2.7.2.2.10 Cellulases and Hemicellulases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153 2.7.2.2.11 Lysozyme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153 2.7.2.2.12 Thioglucosidase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153 2.7.2.2.13 Pectolytic Enzymes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153 2.7.2.2.14 Lipases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154 2.7.2.2.15 Tannases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154 2.7.2.2.16 Glutaminase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154 2.7.2.3 Isomerases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154 2.7.2.4 Transferases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154 2.8 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
xiiContents3158Lipids.3.1158Foreword3.2159Fatty Acids..3.2.1159Nomenclature and Classification.3.2.1.1159SaturatedFattyAcids3.2.1.2162UnsaturatedFattyAcids3.2.1.3164Substituted Fatty Acids..3.2.2165Physical Properties3.2.2.1165Carboxyl Group....3.2.2.2165Crystalline Structure, Melting Points3.2.2.3166Urea Adducts...3.2.2.4167Solubility3.2.2.5UV-Absorption:1673.2.3Chemical Properties.1673.2.3.1.167Methylation of Carboxyl Groups.3.2.3.2...168Reactionsof UnsaturatedFattyAcids3.2.3.2.1Halogen Addition Reactions168......3.2.3.2.2Transformation of Isolene-Type Fatty Acids168to Conjugated Fatty Acids ..3.2.3.2.3168Formationofaπ-ComplexwithAg+Ions.3.2.3.2.4169Hydrogenation..3.2.4169Biosynthesis of Unsaturated Fatty Acids3.3169Acylglycerols.....3.3.1Triacylglycerols (TG) :1703.3.1.1170Nomenclature,Classification,CalorificValue3.3.1.2171Melting Properties....1723.3.1.3Chemical Properties3.3.1.4173Structural Determination3.3.1.5.177Biosynthesis...3.3.2177Mono- and Diacylglycerols (MG, DG)..3.3.2.1177Occurrence,Production3.3.2.2Physical Properties1783.4Phospho- and Glycolipids1783.4.1178Classes ......3.4.1.1Phosphatidyl Derivatives1783.4.1.2180Glyceroglycolipids3.4.1.3181Sphingolipids...3.4.2182Analysis....3.4.2.1182Extraction, Removal of Nonlipids3.4.2.2182Separation and Identification of Classes of Components1833.4.2.3Analysis of Lipid Components3.5183Lipoproteins, Membranes3.5.1.183Lipoproteins3.5.1.1:183Definition...3.5.1.2184Classification....3.5.2Involvementof Lipids intheFormation185of Biological Membranes.....3.6186Diol Lipids, Higher Alcohols, Waxes and Cutin3.6.1186Diol Lipids....3.6.2186Higher Alcohols and Derivatives.3.6.2.1Waxes..186
xii Contents 3 Lipids. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158 3.1 Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158 3.2 Fatty Acids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 3.2.1 Nomenclature and Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 3.2.1.1 Saturated Fatty Acids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 3.2.1.2 Unsaturated Fatty Acids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162 3.2.1.3 Substituted Fatty Acids. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164 3.2.2 Physical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165 3.2.2.1 Carboxyl Group. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165 3.2.2.2 Crystalline Structure, Melting Points . . . . . . . . . . . . . . . . . . . . . . . 165 3.2.2.3 Urea Adducts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166 3.2.2.4 Solubility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167 3.2.2.5 UV-Absorption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167 3.2.3 Chemical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167 3.2.3.1 Methylation of Carboxyl Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . 167 3.2.3.2 Reactions of Unsaturated Fatty Acids . . . . . . . . . . . . . . . . . . . . . . . 168 3.2.3.2.1 Halogen Addition Reactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168 3.2.3.2.2 Transformation of Isolene-Type Fatty Acids to Conjugated Fatty Acids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168 3.2.3.2.3 Formation of a π-Complex with Ag+ Ions . . . . . . . . . . . . . . . . . . . 168 3.2.3.2.4 Hydrogenation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169 3.2.4 Biosynthesis of Unsaturated Fatty Acids . . . . . . . . . . . . . . . . . . . . 169 3.3 Acylglycerols. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169 3.3.1 Triacylglycerols (TG) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170 3.3.1.1 Nomenclature, Classification, Calorific Value . . . . . . . . . . . . . . . . 170 3.3.1.2 Melting Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 3.3.1.3 Chemical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172 3.3.1.4 Structural Determination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173 3.3.1.5 Biosynthesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177 3.3.2 Mono- and Diacylglycerols (MG, DG) . . . . . . . . . . . . . . . . . . . . . . 177 3.3.2.1 Occurrence, Production . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177 3.3.2.2 Physical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178 3.4 Phospho- and Glycolipids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178 3.4.1 Classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178 3.4.1.1 Phosphatidyl Derivatives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178 3.4.1.2 Glyceroglycolipids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180 3.4.1.3 Sphingolipids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181 3.4.2 Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182 3.4.2.1 Extraction, Removal of Nonlipids . . . . . . . . . . . . . . . . . . . . . . . . . . 182 3.4.2.2 Separation and Identification of Classes of Components . . . . . . . 182 3.4.2.3 Analysis of Lipid Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183 3.5 Lipoproteins, Membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183 3.5.1 Lipoproteins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183 3.5.1.1 Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183 3.5.1.2 Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184 3.5.2 Involvement of Lipids in the Formation of Biological Membranes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185 3.6 Diol Lipids, Higher Alcohols, Waxes and Cutin . . . . . . . . . . . . . . 186 3.6.1 Diol Lipids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186 3.6.2 Higher Alcohols and Derivatives . . . . . . . . . . . . . . . . . . . . . . . . . . . 186 3.6.2.1 Waxes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
xiiiContents3.6.2.2187Alkoxy Lipids3.6.3187Cutin..3.7Changes in Acyl Lipids of Food1873.7.1187Enzymatic Hydrolysis3.7.1.1Triacylglycerol Hydrolases (Lipases)1883.7.1.2190Polar-Lipid Hydrolases.3.7.1.2.1190Phospholipases....3.7.1.2.2190Glycolipid Hydrolases ..3.7.2191Peroxidation of Unsaturated Acyl Lipids3.7.2.1191Autoxidation3.7.2.1.1192Fundamental StepsofAutoxidation....3.7.2.1.2193Monohydroperoxides.1953.7.2.1.3Hydroperoxide-Epidioxides ..1963.7.2.1.4InitiationofaRadicalChainReaction.1963.7.2.1.5Photooxidation3.7.2.1.6198HeavyMetal lons.+2003.7.2.1.7Heme(in) Catalysis ...3.7.2.1.8ActivatedOxygen....2013.7.2.1.9203Secondary Products3.7.2.2207Lipoxygenase:Occurrence and Properties3.7.2.3.209Enzymatic Degradation of Hydroperoxides3.7.2.4211Hydroperoxide-Protein Interactions3.7.2.4.1.211Products Formed from Hydroperoxides3.7.2.4.2.212Lipid-Protein Complexes...3.7.2.4.3213Protein Changes.2143.7.2.4.4Decomposition of Amino Acids3.7.3.214InhibitionofLipidPeroxidation3.7.3.1.215Antioxidant Activity.3.7.3.2215Antioxidants in Food3.7.3.2.1.215Natural Antioxidants.3.7.3.2.2**.218Synthetic Antioxidants.3.7.3.2.3219Synergists...2203.7.3.2.4ProoxidativeEffect3.7.4220Fat or Oil Heating (Deep Frying)2213.7.4.1Autoxidation of Saturated Acyl Lipids3.7.4.2223Polymerization3.7.5224Radiolysis2253.7.6Microbial Degradation of Acyl Lipids to Methyl Ketones3.8225Unsaponifiable Constituents2273.8.1Hydrocarbons2273.8.2Steroids2273.8.2.1Structure, Nomenclature.3.8.2.2.227Steroids of Animal Food3.8.2.2.1.227Cholesterol..3.8.2.2.2....229VitaminD...2293.8.2.3Plant Steroids (Phytosterols)2293.8.2.3.1Desmethylsterols..2313.8.2.3.2Methyl- and Dimethylsterols2323.8.2.4Analysis...3.8.3233Tocopherols and Tocotrienols3.8.3.1233Structure,Importance
Contents xiii 3.6.2.2 Alkoxy Lipids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187 3.6.3 Cutin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187 3.7 Changes in Acyl Lipids of Food . . . . . . . . . . . . . . . . . . . . . . . . . . . 187 3.7.1 Enzymatic Hydrolysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187 3.7.1.1 Triacylglycerol Hydrolases (Lipases) . . . . . . . . . . . . . . . . . . . . . . . 188 3.7.1.2 Polar-Lipid Hydrolases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190 3.7.1.2.1 Phospholipases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190 3.7.1.2.2 Glycolipid Hydrolases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190 3.7.2 Peroxidation of Unsaturated Acyl Lipids . . . . . . . . . . . . . . . . . . . . 191 3.7.2.1 Autoxidation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191 3.7.2.1.1 Fundamental Steps of Autoxidation . . . . . . . . . . . . . . . . . . . . . . . . 192 3.7.2.1.2 Monohydroperoxides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193 3.7.2.1.3 Hydroperoxide-Epidioxides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195 3.7.2.1.4 Initiation of a Radical Chain Reaction . . . . . . . . . . . . . . . . . . . . . . 196 3.7.2.1.5 Photooxidation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196 3.7.2.1.6 Heavy Metal Ions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198 3.7.2.1.7 Heme(in) Catalysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 3.7.2.1.8 Activated Oxygen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201 3.7.2.1.9 Secondary Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203 3.7.2.2 Lipoxygenase: Occurrence and Properties . . . . . . . . . . . . . . . . . . . 207 3.7.2.3 Enzymatic Degradation of Hydroperoxides . . . . . . . . . . . . . . . . . . 209 3.7.2.4 Hydroperoxide–Protein Interactions . . . . . . . . . . . . . . . . . . . . . . . . 211 3.7.2.4.1 Products Formed from Hydroperoxides . . . . . . . . . . . . . . . . . . . . . 211 3.7.2.4.2 Lipid–Protein Complexes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212 3.7.2.4.3 Protein Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213 3.7.2.4.4 Decomposition of Amino Acids . . . . . . . . . . . . . . . . . . . . . . . . . . . 214 3.7.3 Inhibition of Lipid Peroxidation . . . . . . . . . . . . . . . . . . . . . . . . . . . 214 3.7.3.1 Antioxidant Activity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215 3.7.3.2 Antioxidants in Food . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215 3.7.3.2.1 Natural Antioxidants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215 3.7.3.2.2 Synthetic Antioxidants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218 3.7.3.2.3 Synergists . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219 3.7.3.2.4 Prooxidative Effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220 3.7.4 Fat or Oil Heating (Deep Frying) . . . . . . . . . . . . . . . . . . . . . . . . . . 220 3.7.4.1 Autoxidation of Saturated Acyl Lipids . . . . . . . . . . . . . . . . . . . . . . 221 3.7.4.2 Polymerization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223 3.7.5 Radiolysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224 3.7.6 Microbial Degradation of Acyl Lipids to Methyl Ketones . . . . . . 225 3.8 Unsaponifiable Constituents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225 3.8.1 Hydrocarbons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227 3.8.2 Steroids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227 3.8.2.1 Structure, Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227 3.8.2.2 Steroids of Animal Food . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227 3.8.2.2.1 Cholesterol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227 3.8.2.2.2 Vitamin D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229 3.8.2.3 Plant Steroids (Phytosterols) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229 3.8.2.3.1 Desmethylsterols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229 3.8.2.3.2 Methyl- and Dimethylsterols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231 3.8.2.4 Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232 3.8.3 Tocopherols and Tocotrienols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233 3.8.3.1 Structure, Importance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233