Foreword The art of cheesemaking has been augmented steadily by greater knowledge on the science of cheesemaking. This evolution has resulted from basic and applied research and from the increased need to understand and control the characteristics of milk, the microorganisms used in the manufacture and maturation of cheese, the manufacturing technologies, and the physical properties and flavour of cheese. Traditional methods of cheese manufacture have been modified by the need for greater efficiencies in the manufacture and maturation of cheese and by changes in the marketing channels for cheese. Accommodating these changes while maintaining the characteristics of a given cheese variety has been accomplished by the application of scientific principles. The need for greater under- standing of the characteristics of cheese has also been driven by the increased use of cheese as an ingredient in other foods. This has required specific control of selected properties of cheese to impart the desired properties to the food, and to retain characteristics of the cheese during various food processing technologies. The successive editions of :eseehC Chemistry, Physics dna Microbiology have documented the application of science to the art of cheesemaking. Certain characteristics are common in all editions: a thorough description and evaluation of scientific and technological advances, prodigious referencing to direct readers to more in-depth discussion of topics, and careful editing to impart consistency of discussion and a smooth transition between chapters. However, each edition has been revised to incorporate new information and to reflect recent trends in describing the science of cheesemaking and maturation and in the use of cheese as a food ingredient. Scientific principles emphasised in Volume 1 cover microbiological, chemical and physical attributes of cheese as in previous editions. Greater emphasis is given to the genetics and metabolic activity of lactic starters and on the secondary microflora in the third edition. Conversion of components (lactose, lactate, citrate, lipids, proteins) by microbial metabolism and enzymatic action is discussed in several chapters. Inclusion of modern sensory evaluation tech- niques and instrumental identification of flavour compounds recognises the relationship between these areas. A new chapter on acid gels provides the basic background for discussion in Volume 2 on cheese varieties made by acid or heat plus acid coagulation that are becoming more important as food ingredients. Volume 2, as in previous editions, focuses on various types of cheese, but the cheeses have been grouped into more logical categories based upon characteristics rather than geographical regions of production. The first chapter of Volume 2 pro- vides an overview of the diversity of cheese varieties and systems of categorising varieties. A similar approach in the second chapter familiarises the reader with the general aspects of cheese technology to emphasise that there are common elements in cheesemaking and maturation and that cheese varieties result from specific deviations from or additions to these common elements. The last chapter is appropriately a discussion of cheese as an ingredient, which recognises recent trends in the science of cheese. A substantial bank of knowledge has been accumulated on cheese and this has been rigorously incorporated into the two volumes. It is inevitable that this bank of knowledge will be revised and expanded. The third edition of :eseehC Chemistry, Physics dna ygoloiborciM provides the base upon which these revisions and expansions can be undertaken objectively. N.E Olson Department of Food Science, University of Wisconsin, Madison List of Contributors Dr J.M. Banks Ms Y.E Collins CHARIS Food Research Dairy Products Research Centre Hannah Research Institute Teagasc, Moorepark Ayr KA6 5HL Fermoy Scotland Cork Ireland Dr .T Beresford Dairy Products Research Centre Professor M.J.C. Crabbe Teagasc, Moorepark Division of Cell and Molecular Biology Fermoy School of Animal and Microbial Sciences Cork The University of Reading Ireland Whiteknights Reading RG6 JA6 Dr E. Beuvier UK Station de Recherches en Technologie et Analyses Dr A.C. Curtin Laitieres Department of Food and Nutritional Sciences Institut National de La Recherche Agronomique University College F-39801 Poligny Cedex Cork France Ireland Dr S. Buchin Professor E Dejmek Station de Recherches en Technologie et Analyses Department of Food Engineering Laitieres Lund University Institut National de La Recherche Agronomique Box 124, 221 00 Lund F-39801 Poligny Cedex Sweden France Dr C.M. Delahunty Dr M.J. Callanan Department of Food and Nutritional Sciences Dairy Products Research Centre University College Teagasc, Moorepark Cork Fermoy Ireland Cork Ireland Dr A.D.W. Dobson Department of Microbiology Dr J.-E Chamba University College Institut Technique Francais de Fromages Cork 74801 La Roche sur Foron Cedex Ireland France Dr C.W. Donnelly Professor T.M. Cogan Department of Nutrition and Food Sciences Dairy Products Research Centre University of Vermont Teagasc, Moorepark 200 Carrigan Building Fermoy Burlington Cork VT 05405-0044 Ireland USA x List of Contributors Dr M.A. Drake Dr A.A.A. Magboul Department of Food Science LAD Food Industries North Carolina State University Industrial Area Campus Box 7624 No. 1/15 Block 4F Raleigh Khartoum North, PO xoB 708 NC 27695-7624 Sudan ASU Professor J.-L. Maubois Dr G.E Fitzgerald Laboratoire de Recherches kaiti~res National Food Biotechnology Centre Institut National de la Recherche Departments of Microbiology and Food & Nutritional Agronomique Sciences 35012 Rennes Cedex University College France Cork Dr .S McGrath Ireland National Food Biotechnology Centre Department of Microbiology Professor E.P Fox University College Department of Food and Nutritional Sciences Cork University College Ireland Cork Ireland Dr P.L.H. McSweeney Department of Food and Dr T.P. Guinee Nutritional Sciences Dairy Products Research Centre University College Teagasc, Moorepark Cork Fermoy Ireland Cork Ireland Professor .V.V Mistry Dairy Science Department Dr D.S. Horne South Dakota State University SIRAHC Food Research Brookings Hannah Research Institute DS 57007 ryA 6AK 5HL ASU Scotland Dr N.M. O'Brien Dr E Irlinger Department of Food and Institut National de aL Recherche Agronomique Nutritional Sciences 78850 Thiverval-Grignon Cedex University College France Cork Ireland Dr J.-L. eL Qu~r~ Institut National de al Recherche Agronomique Dr D.J. O'Callaghan Unit6 Mixte de Recherche sur les Aromes Dairy Products Research Centre 71 rue Sully Teagasc, Moorepark F-21065, Dijon Fermoy France Cork Ireland Dr J.A. Lucey Department of Food Science Dr J. O'Callaghan University of Wisconsin-Madison Department of Microbiology 1605 Linden Drive University College Madison, WI 53706-1565 Cork ASU Ireland List of Contributors ix Dr T.P. O'Connor Mr V.K. Upadhyay Department of Food and Nutritional Sciences Department of Food and Nutritional Sciences University College University College Cork Cork Ireland Ireland Dr E. Parente Professor .P Walstra Dipartimenta Biologia Department of Food Science Universit/~ della Basilicata The Argricultural University Campus di Macchia Romana 6703 HD Wageningen 85100 Potenza The Netherlands Italy Dr M.G. Wilkinson Dr R.P. Ross Department of Life Sciences Dairy Products Research Centre University of Limerick Teagasc, Moorepark Castletroy Fermoy Limerick Cork Ireland Ireland Dr D. van Sinderen Professor .A Williams Department of Microbiology CHARIS Food Research University College Hannah Research Institute Cork Ayr KA6 5HL Ireland Scotland Preface to the First Edition Cheese manufacture is one of the classical examples of food preservation, dating from 6000-7000 BC. Preserva- tion of the most important constituents of milk (i.e. fat and protein) as cheese exploits two of the classical prin- ciples of food preservation, i.e.: lactic acid fermentation, and reduction of water activity through removal of water and addition of NaC1. Establishment of a low redox potential and secretion of antibiotics by starter microorganisms contribute to the storage stability of cheese. About 500 varieties of cheese are now produced throughout the world; present production is -107 tonnes per annum and is increasing at a rate of %4~-- per annum. Cheese manufacture essentially involves gelation of the casein via iso-electric (acid) or enzymatic (rennet) coagulation; a few cheeses are produced by a combination of heat and acid and still fewer by thermal evaporation. Developments in ultrafihration facilitate the production of a new family of cheeses. Cheeses produced by acid or heat/acid coagulation are usually consumed fresh, and hence their production is relatively simple and they are not particularly interesting from the biochemical view- point although they may have interesting physico-chemical features. Rennet cheeses are almost always ripened (matured) before consumption through the action of a complex battery of enzymes. Consequently they are in a dynamic state and provide fascinating subjects for enzymologists and microbiologists, as well as physical chemists. Researchers on cheese have created a very substantial literature, including several texts dealing mainly with the technological aspects of cheese production. Although certain chemical, physical and microbiological aspects of cheese have been reviewed extensively, this is probably the first attempt to review comprehensively the scien- tific aspects of cheese manufacture and ripening. The topics applicable to most cheese varieties, i.e. rennets, starters, primary and secondary phases of rennet coagulation, gel formation, gel syneresis, salting, proteolysis, theology and nutrition, are reviewed in Volume .1 Volume 2 is devoted to the more specific aspects of the nine major cheese families: Cheddar, Dutch, Swiss, Iberian, Italian, Balkan, Middle Eastern, Mould-ripened and Smear-ripened. A chapter is devoted to non-European cheeses, many of which are ill-defined; it is hoped that the review will stimulate scientific interest in these minor, but locally important, varieties. The final chapter is devoted to processed cheeses. It is hoped that the book will provide an up-to-date reference on the scientific aspects of this fascinating group of ancient, yet ultramodern, foods; each chapter is extensively referenced. It will be clear that a consider- ably body of scientific knowledge on the manufacture and ripening of cheese is currently available but it will be apparent also that many major gaps exist in our knowledge; it is hoped that this book will serve to stimulate sci- entists to fill these gaps. I wish to thank sincerely the other 26 authors who contributed to the text and whose co-operation made my task as editor a pleasure. ER Fox Preface to the Second Edition The first edition of this book was very well received by the various groups (lecturers, students, researchers and industrialists) interested in the scientific and technological aspects of cheese. The initial printing was sold out faster than anticipated and created an opportunity to revise and extend the book. The second edition retains all 21 subjects from the first edition, generally revised by the same authors and in some cases expanded considerably. In addition, l0 new chapters have been added: Cheese: Methods of chemical analysis; Biochemistry of cheese ripening; Water activity and the composition of cheese; Growth and survival of pathogenic and other undesirable microorganisms in cheese; Membrane processes in cheese technology, in Volume 1 and North-European varieties; Cheeses of the former USSR; Mozzarella and Pizza cheese; Acid-coagulated cheeses and Cheeses from sheep's and goats' milk in Volume .2 These new chapters were included mainly to fill perceived deficiencies in the first edition. The book provides an in-depth coverage of the principal scientific and technological aspects of cheese. While it is intended primarily for lecturers, senior students and researchers, production management and quality con- trol personnel should find it to be a very valuable reference book. Although cheese production has become increasingly scientific in recent years, the quality of the final product is still not totally predictable. It is not claimed that this book will provide all the answers for the cheese scientist/technologist but it does provide the most comprehensive compendium of scientific knowledge on cheese available. Each of the 31 chapters is extensively referenced to facilitate further exploration of the extensive literature on cheese. It will be apparent that while cheese manufacture is now firmly based on sound scientific principles, many questions remain unanswered. It is hoped that this book will serve to stimulate further scientific study on the chemical, physical and biological aspects of cheese. I wish to thank sincerely all the authors who contributed to the two volumes of this book and whose co- operation made my task as editor a pleasure. RE Fox Preface to the Third Edition Very considerable progress has been made on the scientific aspects of cheese since the second edition of this book was published in 1993. This is especially true for the Microbiology of Cheese and the Biochemistry of Cheese Ripening; consequently those sections have been expanded very considerably. The general structure of the book is similar to that of the earlier editions, with the more general aspects being treated in Volume 1 and the more applied, variety-related aspects in Volume 2. The book contains 36 chapters. Reflecting the very exten- sive research on cheese starters in recent years, four chapters have been devoted to this topic in the third edition. Another new feature is the inclusion of two chapters on cheese flavour; one on sensory aspects, the other on instrumental methods. In Volume 2 of the second edition, cheese varieties were treated mainly on a geographical basis. While some elements of the geographical distribution remain, cheese varieties are now treated mainly based on the charac- teristic features of their ripening. Obviously, it is not possible to treat all 1000 or so cheese varieties, but the 10 variety-related chapters in Volume 2 cover at least 90% of world cheese production and it is very likely that your favourite cheese is included in one of those 10 chapters. Cheese is the quintessential convenience food and is widely used as an ingredient in other foods and in the USA approximately 70% of all cheese is used as a food ingredient. The use of cheese as a food ingredient is a major growth area; consequently, a chapter has been devoted to the important features of cheese as an ingredi- ent, including a section on Enzyme-modified Cheese. Each chapter is extensively referenced to facilitate further exploration of the extensive literature on cheese. While the book is intended for primarily lecturers, senior students and researchers, production management and quality control personnel should find it to be a very useful reference book. We wish to thank sincerely all authors who contributed to the two volumes of this book and whose co- operation made our task as editors a pleasure. Special thanks are due to Ms Anne Cahalane for very valuable assistance. RE Fox P.L.H. McSweeney T.M. Cogan T.R Guinee Cheese: An Overview .F.P Fox and P.L.H. McSweeney, Department of Food and Nutritional ,secneicS University College, Cork, Ireland Historical Milk is also a rich source of nutrients for bacteria Cheese is the generic name for a group of fermented which contaminate the milk, some species of which milk-based food products, produced in a wide range of utilize milk sugar, lactose, as a source of energy, produc- flavours and forms throughout the world. Although the ing lactic acid. Bacterial growth and acid production primary objective of cheesemaking is to conserve the would have occurred during storage or during attempts principal constituents of milk, cheese has evolved to to dry milk in the prevailing warm, dry climate to pro- become a food of haute cuisine with epicurean qualities, duce a more stable product- air-drying of meat, fruits as well as being highly nutritious. Sandine and Elliker and vegetables appears to have been practised as a primi- (1970) suggested that there are more than 1000 var- tive form of food preservation at this period in the devel- ieties of cheese. Walter and Hargrove (1972) described opment of civilization. When sufficient acid has been more than 400 varieties and listed the names of a further produced, the principal proteins of milk, the caseins, 400, while Burkhalter (1981) classified 510 varieties coagulate, i.e., at their isoelectric points- --~pH 4.6, to (although some are listed more than once). Jim Path form a gel in which the fat is entrapped. The rate of acid- (University of Wisconsin) has compiled a list of 1400 ification by the adventitious microflora would usually be varieties (visit www.cdr.wisc.edu). As discussed in detail slow, allowing the (unhomogenized) fat globules to form in 'Diversity of cheese varieties: An Overview', Volume 2, a cream layer. This layer of sour cream could be blended a number of attempts have been made to classify cheese into the lower protein gel or scooped off for the produc- varieties into meaningful groups. The most common tion of butter. Thus originated three of our classical criterion for the classification is texture (very hard, fermented dairy products: fermented milks, sour cream hard, semi-hard, semi-soft, soft) which is related mainly and lactic butter, all of which are still produced widely, to the moisture content of the cheese. Various attempts sometimes depending on the adventitious microflora for have been made to improve on this basis of classifica- acidification, but now usually through the growth of cul- tion, for example, by including the milk-producing tures of lactic acid bacteria. species, moisture to protein ratio, method of coagula- The first fermented dairy foods were produced by tion, cooking temperature, microflora. These classifica- a fortuitous combination of events- the ability of a tion schemes are discussed in 'Diversity of cheese group of bacteria, the lactic acid bacteria (LAB), to grow varieties: An Overview', Volume .2 However, no classifi- in milk and to produce enough acid to reduce the cation scheme developed to date is completely satisfac- pH of milk to the isoelectric point of the caseins, at tory; the inclusion of chemical indices of ripening which these proteins coagulate. Neither the BAL nor the would be useful. caseins were designed for this outcome. The caseins It is commonly believed that cheese evolved in a were 'designed' to coagulate following limited proteoly- region known as the 'Fertile Crescent', i.e., from the sis in the stomach of neonatal mammals, the gastric Tigris and Euphratres rivers, through what is now pH of which is around 6, i.e., very much higher than southern Turkey to the Mediterranean coast, some the isoelectric point of the caseins. The ability of Lacto- 8000 years ago. The so-called 'Agricultural Revolu- coccus lactis to ferment lactose, a sugar specific to milk, tion' occurred in this region with the domestication of is plasmid-encoded, suggesting that this characteristic plants and animals. Presumably, humans soon recog- was acquired relatively recently in the evolution of these nized the nutritive value of milk produced by domes- bacteria. Their natural habitats are vegetation and/or ticated animals and contrived to share the mother's the intestine, from which they presumably colonized milk with her offspring. Apparently, goats and sheep, the teats of dairy animals, contaminated with lactose- which are gregarious and docile, were the first dairy containing milk; it is likely that through evolutionary animals domesticated, but cattle have become the pressure, these bacteria acquired the ability to ferment dominant dairy species in most parts of the world lactose. (c. 85% of the total world supply of milk is obtained When an acid-coagulated milk gel is broken, e.g., acci- from cows). dentally by movement of the storage vessel or intentionally Cheese: Chemistry, Physics and Microbiology, Third edition - Volume :1 General Aspects Copyright (cid:14)9 2004 Elsevier Ltd ISBN: 0-1226-3652-X All rights reserved Set ISBN: 0-1226-3651-1 2 Cheese: An Overview by breaking or cutting, it separates into curds and whey. It While the coagulation of milk by the in situ produc- would have been realized quickly that the acid whey is a tion of lactic acid was, presumably, accidental, the use pleasant, refreshing drink for immediate consumption of rennets to coagulate milk was intentional. It was, in while the curds could be consumed fresh or stored for fact, quite an ingenous invention- if the conversion of furore use. In fact, whey was long considered to have milk to cheese by the use of rennets was discovered medicinal benefits (see Hoffmann, 1761). It was probably today, it would be hailed as a major biotechnological soon realized that the shelf-life of the curds could be discovery! extended by dehydration and/or by adding salt; heavily The advantages accruing from the ability to convert salted cheese varieties are still widespread throughout the the principal constituents of milk to cheese would Middle East and small quantifies of a number of dehy- have been apparent from the viewpoints of storage sta- drated cheeses are produced in North Africa and the Mid- bility, ease of transport and, presumably, as a means of dle East, e.g., Tikammart and Aoules (Algeria), Djamid diversifying the human diet and cheese manufacture (Jordan), Ekt (Saudi Arabia) and Madraffarah (Syria) (see became well established in the ancient civilizations of Phelan te al., 1993). the Middle East, Egypt, Greece and Rome. There are It is presumed that one of the principal families of numerous references to cheese and other foods in the cheese, the acid cheeses, modern members of which Bible (see MacAlister, 1904). Milk and dairy products include Cottage cheese, Cream cheese and Quarg, origin- formed an important part of the diet of peoples of ated in this way. While lactic acid, produced in situ, is the Near East during Biblical times; indeed Palestine believed to have been the original milk coagulant, an was praised as 'a land flowing with milk and honey' alternative mechanism was also recognized from an (Exodus 3.8). Animals herded during Biblical times early date. Many proteolytic enzymes can modify the for milk production included goats (e.g., Proverbs casein system in milk, causing it to coagulate under cer- 27.27), sheep (e.g., Deuteronomy 14.4) and possibly tain circumstances. Enzymes capable of causing this camels (Genesis 32.15). Cows' milk is rarely specified transformation are widespread in nature, e.g., bacteria, in the Old Testament, presumably because of the moulds, plant and animal tissues, but an obvious source unsuitability of the terrain of the Holy Land for cow would have been animal stomachs. It would have been pasture. In addition to milk, other foods of dairy ori- observed that the stomach of young mammals after gin mentioned in the Bible include curds (perhaps fer- slaughter contained curds, especially if the animals had mented milk: Genesis 18.8; Isaiah 7.22) and butter suckled shortly before slaughter; curds would also have (Psalms 55.21). There are several clear references in been observed in the vomit of human infants. Before the the Old Testament to cheese, e.g., Job (1520 ,CB where development of pottery (---5000 BC), storage of milk in Job remarks to God 'did Thou not pour me out like bags made from animal skins was probably common (as milk and curdle me like cheese'; Job 10.10) and it still is in many countries). Stomachs of slaughtered Samuel (1170-1017 ;CB as a delicacy sent by Jesse to animals provided ready-made, easily sealed containers; his sons (I Samuel 17.18) and as a gift presented to under such circumstances, milk would extract enzymes David (II Samuel 17.29)). (chymosin and some pepsin) from the stomach tissue, Cheese is represented in the tomb art of Ancient leading to its coagulation during storage. The properties Egypt and in Greek literature. Vegetable rennets are of rennet-coagulated curds are very different from those mentioned in the first work of European literature; produced by isoelectric (acid) precipitation, e.g., they Homer (c. eighth century )CB implies the use of fig have better syneresis properties which makes it possible rennet in the Iliad ('... as when fig juice is added to to produce low-moisture cheese curd without harden- white milk and rapidly coagulates, and the milk ing. Rennet-coagulated curds can, therefore, be con- quickly curdles as it is stirred, so speedy was his heal- verted to a more stable product than acid curds and ing of raging Ares.' Iliad 5) and describes the Cyclops, rennet coagulation has become predominant in cheese Polyphemus, making ewes' milk cheese in the Odyssey manufacture, being exploited for .c 75% of total world (Book 9) using 'well made dairy vessels' and 'pails production. swimming with whey'. Other Greek authors who men- Although animal rennets were used from early times, tion cheese include the Father of History, Herodotus rennets produced from a range of plant species, e.g., fig (484-408 BC), who referred to 'Scythian cheese' and and thistle, also appear to have been common in ancient the philosopher, Aristotle (384-322 BC), who noted times. However, plant rennets are not suitable for the that 'Phrygian' cheese was made from the milk of manufacture of long-ripened cheese varieties and gastric mares and asses. Apparently, cheese was prescribed in proteinases from young animals became the standard the diet for Spartan wrestlers in training. rennets until a recent shortage of supply made it neces- Cheese manufacture was well established in the sary to introduce 'rennet substitutes'. Roman Empire and was a standard item in the rations