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Food enzymes: Structure and mechanisms
Book Reviews
Methods to AssessQuality and Stability of Oils and Fat-containingFoods edited bv KathleenWarner and N.A. Michael Eskin,AOCS Press,1995. $80.00 (ix t 220 pages) ISBN 0 935315 58 6 The monograph Quality and Fat-containing
Methods to Assess Stability of Oils and Foods is based on an
American Oil Chemists’ Society short course held in 1991. Unfortunately, it took approximately four years for this book to be published; thus, very few references published after 1991 have been cited. Several important recent developments in the field, such as the use of chemiluminescence and electron paramagnetic resonance to monitor lipid oxidation, have not been mentioned in this volume. However, as stated by the editors, this monograph was written for those laboratory scientists who are establishing protocols to determine oil quality and stability. To this end, the editors have accomplished their goal. The book consists of 11 chapters. An interesting historical review of the developments in methods of fat analysis and sensory evaluation from the 1930s to the 1970s is presented in Chapter 1. Chapter 2 provides a good review of the factors affecting oil quality and stability. A very comprehensive treatment of sensory analyses
of oils and fat-containing foods is given in Chapters 3-5. Because sensory analysis is the optimum test for the quality of oils and fat-containing foods, a detailed discussion on this subject is certainly desirable. In Chapters 6 and 7, the significant volatile flavor compounds in oils and fat-containing foods, and the methods to measure these volatile compounds are discussed; emphasis has been placed on the volatile compounds in vegetable oils - marine oils have not been mentioned. All of the sample preparation methods for gas chromatographic analyses including direct injection, static headspace and dynamic headspace have been discussed. Readers should, however, be aware of the recent development in the use of adsorption-trapping direct short-path thermal desorption or direct short-path thermal desorption gas chromatography for the measurement of volatiles. Gas chromatography olfactometry (GCO) including the ‘charm’ method or aroma extract dilution analysis, is another important recent development that will be
Food Enzymes:Structure and Mechanisms by Dominic W.S. Wong, Chapman & Hall, 1995. f69.00 (xvi t 390 pages)ISBN 0 412 05691 7 Food Enzymes: Structure and Mechanisms attempts to bring together detailed, fully referenced information about the structure and function of enzymes on the one hand, and their application to food processing on the other. The volume begins with a very brief review of the current range of enzyme uses in the food manufacturing and processing sector. This is augmented by some comments on future developments such as recombinant DNA technology, protein engineering and catalytic antibodies. This chapter lacks balance and substance in that no consideration is given to economic, regulatory or consumer-acceptance issues. Also, the author dwells too much on catalytic antibodies and artificial enzymes, the potential of which
176
01996,
Elsevier Science Ltd
in the food area is doubtful and very far downstream. In a book dealing with the food manufacturing sector, a more useful and relevant area to describe and appraise would have been the growing fundamental and applied literature on the modification and exploitation of enzyme behaviour in solvent-free food systems1,2, which has been ignored completely. The second chapter is on tailoring enzyme structures and functions and gives a brief introduction to the advantages of modified enzymes, with inadequate critical appraisal of the special needs of the food processing sector, dealing as it does in relatively low added-value bulk materials, which people expect to be safe to eat. However, such criticism apart, this chapter gives a rational and generally
particularly useful in determining the compound or compounds responsible for the off-flavor of oils and fatcontaining foods; however, GCO is not mentioned in this monograph. Chemical methods, such as peroxide value, conjugated diene, anisidine value and carbonyl value analyses, for the measurement of oil quality are well presented in Chapters 8 and 9. Various accelerated stability tests including the active-oxygen method and the Racimat method are discussed in Chapter 10. The advantages and disadvantages for various tests are briefly but clearly discussed. The most valuable and unique contribution to this volume is probably Chapter 11; T.C. Nelsen, the author of this chapter, has certainly accomplished his goal of making the reader a more intelligent ‘consumer’ of statistics. to Assess In summary, Methods Quality and Fat-containing
Stability of Oils and Foods provides valuable
information on methods for accessing the quality and stability of oils and fat-containing foods. It is recommended to industrial laboratory scientists in quality control and product development who are concerned with the determination of oil quality and stability.
Chi-TangHo Departmentof Food Science,RutgersUniversity, New Brunswick,N/ 08903, USA.
well-referenced account of the scientific basis of protein modification, based on the principles of engineering molecular interactions in order to influence stability, resistance to chemical modification, catalytic efficiency and bond specificity. The bulk of the book is taken up with very comprehensive chapters describing, at a detailed biochemical and molecular level, the structure, characteristics and action mechanisms of the major classes of enzymes used in food processing. Those readers who are attracted to the food aspect of the book’s title will be disappointed by the lack of information on the relevance of these details to food modification, processing and ingredients technology. However, it will appeal to research and development scientists searching for opportunities to use fundamental knowledge as an integral part of wealth-creating R&D programmes. The enzymes covered are: amylases, cellulases, proteinases (although
Trends in Food Science & Technology May 1996 [Vol. 71
exopeptidases are not covered well), lipases and phospholipases, pectin modifiers, a good range of oxidases and oxygenases, and, finally, xylose isomerase - the friend of the soft drinks industry. It is this coverage of the major food enzymes that makes Food Enzymes: Structure and Mechanisms worthwhile as a reference source, obviating the need for researchers and research
Food preservation is important for two reasons: food safety and food quality. New methods of food preservation aim to preserve foods with a minimum loss in quality. New Methods of Food Preservation is the first book to present a comprehensive review of the non-traditional food preservation methods that have been developed during the past 20 years. To a large extent, New Methods of Food Preservation summarizes recent European research efforts in nontraditional food preservation. However, recent research being carried out in North America into high hydrostatic pressure and pulsed electric field processes may well contribute additional information for inclusion in any future edition of this book; it will also need to be updated with respect to the breakthroughs in the inactivation of bacterial spores that are currently being reported at conferences. The objective of the book is to introduce and consolidate information upon which new food preservation methods are based. The methods are categorized into three groups. First, procedures that prevent the access of microorganisms into foods in the first place; examples of this category include aseptic processing and packaging. Second, procedures that should inactivate microorganisms
Aroma Biotechnology contains 12 chapters that attempt to cover everything from what aromas are and the history of aromas in processed foodstuffs, to genetically altered biocatalysts, industrial-scale production and legal issues. The introductory chapter contains an interesting section on the bioactivity of aroma compounds but fails to mention that ‘umami’ (or savoury) has been accepted as the fifth basic taste perception. The chapter on the relevance of biotechnology to aromas is
planners to plough through general enzymology texts. Thus, for those potential readers who already have in-depth knowledge of applied enzymology, this book will make a valuable addition to their reference collection, providing the molecular enzymology to explain function and behaviour as they already observe it, and as they may need it in their fields of application.
B.A. law 3 Sun Gardens, Burghfield Common, Reading, UK RG75)B.
References 1 Vulfson, E.N. (1993) ‘Enzymatic Synthesis of Food Ingredients in Low-water Media’ in TrendsFood Sci. Jechnol. 4,209-215 2 Vulfson, E.N. and Gill, I. (1994) ‘Enzymatic Catalysis in Heterogeneous Eutectic Mixtures of Substrates’in Trends Biofechnol. 12, 118-l 22
New Methodsof FoodPreservation edited by G.W. Gould, Blackie, 1995. f75.00 (xix t 324 pages)ISBN 0 7514 0048 3 they have gained access; examples include high-temperature, short-time processing, microwave and ohmic heating, high hydrostatic pressure treatment, pulsed electric field treatment, ionizing irradiation, pulsedlight irradiation and ozone treatment. Third, procedures that prevent or slow down microbial growth should microorganisms have gained access and not been inactivated; an example includes control of the environment, such as the pH, water activity, temperature and headspace gas composition. New developments in animal-derived, plant-derived and microorganism-derived antimicrobial systems are also covered. Detailed discussion is provided on each method. This book also serves to provide a solid background for those who conduct research in one or more novel preservation technologies. The book begins with an overview of new preservation methods, by the editor, G.W. Gould, and is then divided into 14 chapters, which discuss the following topics: the principles and applications of hurdle technology (by L. Leistner), bacteriocins
(C. Hill), natural antimicrobials from animals and from plants (R.C. Board and C.J.E. Nychas, respectively), food irradiation (P. Loaharanu), microwave processing (J. Mullin), hydrostatic pressure treatment of food (B. Mertens and D. Knorr), effect of heat and ultrasound (F.J. Sala et a/.), electrical resistance heating (P. Fryer), high-voltage pulse techniques (W. Sitzmann), preservation by microbial decontamination (F.J.M. Smulders), advances and potential for aseptic processing (D. Rose) and, finally, advances in modifiedatmosphere packaging (A.R. Davies). Scientists, technologists, students and regulators will find that New Methods of Food Preservation contains the bases of those new methods that have already been commercialized, are under investigation, or have been proposed. Thus, the book should assist the inquirer to understand the complexity and benefits of these new preservation technologies.
Q.H. Zhang Department of Food Science and Technology,
The Ohio State University, 122 Vivian Hall, 212 I Fyffe Road, Columbus, OH 432 JO-1097, USA.
Aroma Biotechnology by Ralf G. Berger,Springer,1995. DM186.00 (240 pages)ISBN 3 540 58606 7 rather short, though it does contain a useful table of references to review articles. The chapters on the de novo synthesis of aroma compounds by microbes and biotransformations are informative, as are those on the use of enzymes and genetically altered biocatalysts. However, no consideration is given to the question of whether the
Trends in Food Science& Technology May 1996 [Vol. 71
products obtained from processes using natural enzymes in artificial environments or conversely artificial enzymes (in natural or artificial environments) can be considered to be natural or not. There is also no mention of the importance of ‘kosherness’, and the constraints that this issue can put on bioprocesses that require the use of certain
01996, Elsevier Science
Ltd
177
Methods to AssessQuality and Stability of Oils and Fat-containingFoods edited bv KathleenWarner and N.A. Michael Eskin,AOCS Press,1995. $80.00 (ix t 220 pages) ISBN 0 935315 58 6 The monograph Quality and Fat-containing
Methods to Assess Stability of Oils and Foods is based on an
American Oil Chemists’ Society short course held in 1991. Unfortunately, it took approximately four years for this book to be published; thus, very few references published after 1991 have been cited. Several important recent developments in the field, such as the use of chemiluminescence and electron paramagnetic resonance to monitor lipid oxidation, have not been mentioned in this volume. However, as stated by the editors, this monograph was written for those laboratory scientists who are establishing protocols to determine oil quality and stability. To this end, the editors have accomplished their goal. The book consists of 11 chapters. An interesting historical review of the developments in methods of fat analysis and sensory evaluation from the 1930s to the 1970s is presented in Chapter 1. Chapter 2 provides a good review of the factors affecting oil quality and stability. A very comprehensive treatment of sensory analyses
of oils and fat-containing foods is given in Chapters 3-5. Because sensory analysis is the optimum test for the quality of oils and fat-containing foods, a detailed discussion on this subject is certainly desirable. In Chapters 6 and 7, the significant volatile flavor compounds in oils and fat-containing foods, and the methods to measure these volatile compounds are discussed; emphasis has been placed on the volatile compounds in vegetable oils - marine oils have not been mentioned. All of the sample preparation methods for gas chromatographic analyses including direct injection, static headspace and dynamic headspace have been discussed. Readers should, however, be aware of the recent development in the use of adsorption-trapping direct short-path thermal desorption or direct short-path thermal desorption gas chromatography for the measurement of volatiles. Gas chromatography olfactometry (GCO) including the ‘charm’ method or aroma extract dilution analysis, is another important recent development that will be
Food Enzymes:Structure and Mechanisms by Dominic W.S. Wong, Chapman & Hall, 1995. f69.00 (xvi t 390 pages)ISBN 0 412 05691 7 Food Enzymes: Structure and Mechanisms attempts to bring together detailed, fully referenced information about the structure and function of enzymes on the one hand, and their application to food processing on the other. The volume begins with a very brief review of the current range of enzyme uses in the food manufacturing and processing sector. This is augmented by some comments on future developments such as recombinant DNA technology, protein engineering and catalytic antibodies. This chapter lacks balance and substance in that no consideration is given to economic, regulatory or consumer-acceptance issues. Also, the author dwells too much on catalytic antibodies and artificial enzymes, the potential of which
176
01996,
Elsevier Science Ltd
in the food area is doubtful and very far downstream. In a book dealing with the food manufacturing sector, a more useful and relevant area to describe and appraise would have been the growing fundamental and applied literature on the modification and exploitation of enzyme behaviour in solvent-free food systems1,2, which has been ignored completely. The second chapter is on tailoring enzyme structures and functions and gives a brief introduction to the advantages of modified enzymes, with inadequate critical appraisal of the special needs of the food processing sector, dealing as it does in relatively low added-value bulk materials, which people expect to be safe to eat. However, such criticism apart, this chapter gives a rational and generally
particularly useful in determining the compound or compounds responsible for the off-flavor of oils and fatcontaining foods; however, GCO is not mentioned in this monograph. Chemical methods, such as peroxide value, conjugated diene, anisidine value and carbonyl value analyses, for the measurement of oil quality are well presented in Chapters 8 and 9. Various accelerated stability tests including the active-oxygen method and the Racimat method are discussed in Chapter 10. The advantages and disadvantages for various tests are briefly but clearly discussed. The most valuable and unique contribution to this volume is probably Chapter 11; T.C. Nelsen, the author of this chapter, has certainly accomplished his goal of making the reader a more intelligent ‘consumer’ of statistics. to Assess In summary, Methods Quality and Fat-containing
Stability of Oils and Foods provides valuable
information on methods for accessing the quality and stability of oils and fat-containing foods. It is recommended to industrial laboratory scientists in quality control and product development who are concerned with the determination of oil quality and stability.
Chi-TangHo Departmentof Food Science,RutgersUniversity, New Brunswick,N/ 08903, USA.
well-referenced account of the scientific basis of protein modification, based on the principles of engineering molecular interactions in order to influence stability, resistance to chemical modification, catalytic efficiency and bond specificity. The bulk of the book is taken up with very comprehensive chapters describing, at a detailed biochemical and molecular level, the structure, characteristics and action mechanisms of the major classes of enzymes used in food processing. Those readers who are attracted to the food aspect of the book’s title will be disappointed by the lack of information on the relevance of these details to food modification, processing and ingredients technology. However, it will appeal to research and development scientists searching for opportunities to use fundamental knowledge as an integral part of wealth-creating R&D programmes. The enzymes covered are: amylases, cellulases, proteinases (although
Trends in Food Science & Technology May 1996 [Vol. 71
exopeptidases are not covered well), lipases and phospholipases, pectin modifiers, a good range of oxidases and oxygenases, and, finally, xylose isomerase - the friend of the soft drinks industry. It is this coverage of the major food enzymes that makes Food Enzymes: Structure and Mechanisms worthwhile as a reference source, obviating the need for researchers and research
Food preservation is important for two reasons: food safety and food quality. New methods of food preservation aim to preserve foods with a minimum loss in quality. New Methods of Food Preservation is the first book to present a comprehensive review of the non-traditional food preservation methods that have been developed during the past 20 years. To a large extent, New Methods of Food Preservation summarizes recent European research efforts in nontraditional food preservation. However, recent research being carried out in North America into high hydrostatic pressure and pulsed electric field processes may well contribute additional information for inclusion in any future edition of this book; it will also need to be updated with respect to the breakthroughs in the inactivation of bacterial spores that are currently being reported at conferences. The objective of the book is to introduce and consolidate information upon which new food preservation methods are based. The methods are categorized into three groups. First, procedures that prevent the access of microorganisms into foods in the first place; examples of this category include aseptic processing and packaging. Second, procedures that should inactivate microorganisms
Aroma Biotechnology contains 12 chapters that attempt to cover everything from what aromas are and the history of aromas in processed foodstuffs, to genetically altered biocatalysts, industrial-scale production and legal issues. The introductory chapter contains an interesting section on the bioactivity of aroma compounds but fails to mention that ‘umami’ (or savoury) has been accepted as the fifth basic taste perception. The chapter on the relevance of biotechnology to aromas is
planners to plough through general enzymology texts. Thus, for those potential readers who already have in-depth knowledge of applied enzymology, this book will make a valuable addition to their reference collection, providing the molecular enzymology to explain function and behaviour as they already observe it, and as they may need it in their fields of application.
B.A. law 3 Sun Gardens, Burghfield Common, Reading, UK RG75)B.
References 1 Vulfson, E.N. (1993) ‘Enzymatic Synthesis of Food Ingredients in Low-water Media’ in TrendsFood Sci. Jechnol. 4,209-215 2 Vulfson, E.N. and Gill, I. (1994) ‘Enzymatic Catalysis in Heterogeneous Eutectic Mixtures of Substrates’in Trends Biofechnol. 12, 118-l 22
New Methodsof FoodPreservation edited by G.W. Gould, Blackie, 1995. f75.00 (xix t 324 pages)ISBN 0 7514 0048 3 they have gained access; examples include high-temperature, short-time processing, microwave and ohmic heating, high hydrostatic pressure treatment, pulsed electric field treatment, ionizing irradiation, pulsedlight irradiation and ozone treatment. Third, procedures that prevent or slow down microbial growth should microorganisms have gained access and not been inactivated; an example includes control of the environment, such as the pH, water activity, temperature and headspace gas composition. New developments in animal-derived, plant-derived and microorganism-derived antimicrobial systems are also covered. Detailed discussion is provided on each method. This book also serves to provide a solid background for those who conduct research in one or more novel preservation technologies. The book begins with an overview of new preservation methods, by the editor, G.W. Gould, and is then divided into 14 chapters, which discuss the following topics: the principles and applications of hurdle technology (by L. Leistner), bacteriocins
(C. Hill), natural antimicrobials from animals and from plants (R.C. Board and C.J.E. Nychas, respectively), food irradiation (P. Loaharanu), microwave processing (J. Mullin), hydrostatic pressure treatment of food (B. Mertens and D. Knorr), effect of heat and ultrasound (F.J. Sala et a/.), electrical resistance heating (P. Fryer), high-voltage pulse techniques (W. Sitzmann), preservation by microbial decontamination (F.J.M. Smulders), advances and potential for aseptic processing (D. Rose) and, finally, advances in modifiedatmosphere packaging (A.R. Davies). Scientists, technologists, students and regulators will find that New Methods of Food Preservation contains the bases of those new methods that have already been commercialized, are under investigation, or have been proposed. Thus, the book should assist the inquirer to understand the complexity and benefits of these new preservation technologies.
Q.H. Zhang Department of Food Science and Technology,
The Ohio State University, 122 Vivian Hall, 212 I Fyffe Road, Columbus, OH 432 JO-1097, USA.
Aroma Biotechnology by Ralf G. Berger,Springer,1995. DM186.00 (240 pages)ISBN 3 540 58606 7 rather short, though it does contain a useful table of references to review articles. The chapters on the de novo synthesis of aroma compounds by microbes and biotransformations are informative, as are those on the use of enzymes and genetically altered biocatalysts. However, no consideration is given to the question of whether the
Trends in Food Science& Technology May 1996 [Vol. 71
products obtained from processes using natural enzymes in artificial environments or conversely artificial enzymes (in natural or artificial environments) can be considered to be natural or not. There is also no mention of the importance of ‘kosherness’, and the constraints that this issue can put on bioprocesses that require the use of certain
01996, Elsevier Science
Ltd
177