constituents of milk, i.e., lactose, lipids, proteins and salts, and variations in theconcentrations and properties of these constituents.The natural function of milk is to supply the ne
Trang 1Dairy processing
Improving quality
Edited by Gerrit Smit
Trang 2Abington Hall, Abington
First published 2003, Woodhead Publishing Limited and CRC Press LLC
ß 2003, Woodhead Publishing Limited
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Trang 3Chapter 1
Professor Gerrit Smit
Manager of the Department of
Flavour, Nutrition and Ingredients
NIZO Food Research
Chapter 3
Dr Mike BolandExecutive Manager ScienceFonterra Research CentrePalmerston NorthNew ZealandTel: +64 (0) 6 350 4664Fax: +64 (0) 6 350 6320Mobile: +64 21338049E-mail: mike.boland@fonterra.com
Chapter 4
Dr ir Meike C te GiffelDepartment of Processing, Qualityand Safety
NIZO Food ResearchKernhemseweg 2
Contributor contact details
Trang 4Food Research Program
Agriculture and Agri-Food Canada
93 Stone Road West
NIZO Food ResearchKernhemseweg 2
PO Box 20
6710 BA EdeThe NetherlandsTel: +31 (0) 318 659511Fax: +31 (0) 318 650400Direct call: +31 (0) 318 659638E-mail: Alexandra.Boelrijk@nizo.nlhttp://www.nizo.com
Chapter 8
Dr D Jaros and Professor H RohmInstitute of Food Technology andBioprocess EngineeringDresden University of TechnologyD-01062 Dresden
GermanyE-mail:
harald.rohm@mailbox.tu-dresden.dedoris.jaros@mailbox.tu-dresden.de
Chapter 9
Professor Donald MuirHannah Research InstituteHannah Research ParkAyr
KA6 5HLScotlandTel: +44 (0) 1292 670170Fax: +44 (0) 1292 670180E-mail:
donald.muir@charisfoods.co.uk
Trang 5Chapter 10
Professor Franz Ulberth
Department of Dairy Research and
PO Box 20
6710 BA EdeThe NetherlandsTel: +31 (0) 318 659511Fax: +31 (0) 318 650400E-mail: Geert.Ellen@nizo.nl
Chapter 14
Dr Aziz AmineFaculte´ de Sciences et TechniquesUniversite´ Hassan II-Mohammedia
20650 MohammediaMorocco
Tel: +212.23.314705; /315352/314708
Fax: +212.23.315353E-mail: aziz-amine@uh2m.ac.ma
Dr Laura Micheli, Dr Danila Mosconeand Professor Giuseppe PalleschiDipartmente di Scienze e TecnologieChimiche
Universita` di Roma ‘Tor Vergata’Via della Ricerca ScientificaRome
ItalyTel: +39 06 7259 4423Fax: +39 06 7259 4328E-mail:
Giuseppe.Palleschi@uniroma2.itContributors contact details xv
Trang 6Stocking HallIthaca
NY 14853USA
Chapter 19
Dr P L H McSweeneyDepartment of Food and NutritionalSciences
University CollegeCork
IrelandTel: +353 21 490 2011 (direct line)Fax: +353 21 427 0001
E-mail: p.mcsweeney@ucc.iehttp://cheese.ucc.ie
Mr V K UpadhyayDepartment of Food and NutritionalSciences
University CollegeCork
Ireland
Chapter 20
Dr Tom BeresfordDairy Products Research CentreMoorepark
Fermoy
Co CorkIrelandTel: +353 025 42222Fax: +353 025 42340E-mail:
tberesford@moorepark.teagasc.ie
Trang 7Chapter 21
Dr W Bockelmann
Institut fu¨r Mikrobiologie
Bundesanstalt fu¨r Milchforschung
Chapter 23
D Givens and K ShingfieldThe University of ReadingReading RG6 6ARUK
E-mail: d.i.givens@reading.ac.ukContributors contact details xvii
Trang 8Contributor contact details xiii
1 Introduction 1
G Smit, NIZO Food Research, The Netherlands Part I Dairy product safety and quality 3
2 The major constituents of milk 5
P F Fox, University College Cork, Ireland 2.1 Introduction 5
2.2 Lactose 7
2.3 Lipids 12
2.4 Proteins 18
2.5 Minor proteins 26
2.6 Salts 36
2.7 References 38
3 Influences on raw milk quality 42
M Boland, Fonterra Research Centre, New Zealand 3.1 Introduction 42
3.2 Breed, genetics and milk quality 45
3.3 Cow diet and milk quality 52
3.4 Other aspects of animal husbandry and milk quality 55
3.5 Future trends 59
3.6 Sources of further information and advice 61
3.7 Acknowledgements 62
3.8 References 62
Contents
Trang 94 Good hygienic practice in milk processing 68
M C te Giffel, NIZO Food Research, The Netherlands 4.1 Introduction 68
4.2 The principal hazards 69
4.3 Good hygienic practice 72
4.4 Future trends 77
4.5 Sources of further information and advice 79
4.6 Bibliography 79
5 Improvements in the pasteurisation and sterilisation of milk 81
M J Lewis, The University of Reading, UK 5.1 Introduction 81
5.2 Kinetic parameters in heat inactivation 82
5.3 Thermisation and tyndallisation 83
5.4 Pasteurisation 85
5.5 Factors affecting the effectiveness of pasteurisation 86
5.6 Extended shelf-life milks 92
5.7 Sterilisation 92
5.8 Ultra-high temperature (UHT) sterilisation 95
5.9 Aseptic packaging and storage 100
5.10 References 100
6 Modelling the effectiveness of pasteurisation 104
R C McKellar, Agriculture and Agri-Food Canada 6.1 Introduction: the role of predictive modelling 104
6.2 The development of thermal models 105
6.3 Key steps in model development 110
6.4 Models for key enzymes and pathogens 115
6.5 Modelling and risk assessment 117
6.6 Risk assessment and pasteurisation 121
6.7 Future trends 124
6.8 Sources of further information and advice 125
6.9 References 126
7 Flavour generation in dairy products 130
A E M Boelrijk, C de Jong and G Smit, NIZO Food Research, The Netherlands 7.1 Introduction 130
7.2 Raw and heat-treated milk 134
7.3 Yoghurt and buttermilk 142
7.4 Conclusion and future trends 147
7.5 Acknowledgements 148
7.6 References 148
vi Contents
Trang 108 Controlling the texture of fermented dairy products:
the case of yoghurt 155
D Jaros and H Rohm, Dresden University of Technology, Germany 8.1 Introduction 155
8.2 The manufacture of yoghurt 155
8.3 Factors affecting yoghurt texture 160
8.4 Measuring the rheological and textural properties of yoghurt 166 8.5 Future trends 174
8.6 Sources of further information and advice 176
8.7 References 176
9 Factors affecting the shelf-life of milk and milk products 185
D D Muir and J M Banks, Hannah Research Institute, UK 9.1 Introduction 185
9.2 Chemical composition and principal reactions of milk 186
9.3 Bacteria in milk and related enzyme activity 190
9.4 Raw milk enzymes 193
9.5 Control of the quality of short shelf-life products 194
9.6 Yoghurt and fermented milk 197
9.7 Factors affecting the stability of long shelf-life products 198
9.8 Control of the stability of long-life milk products 200
9.9 Summary 206
9.10 Acknowledgement 206
9.11 Bibliography 206
10 Testing the authenticity of milk and milk products 208
F Ulberth, University of Agricultural Sciences, Austria 10.1 Introduction 208
10.2 Detecting and quantifying foreign fats 210
10.3 Detecting milk of different species 214
10.4 Detection of non-milk proteins, watering of milk and alteration of casein/whey protein ratio 218
10.5 Measuring heat load 220
10.6 Identifying geographical origin 221
10.7 Conclusions 222
10.8 References 223
11 Functional dairy products 229
M Saxelin, R Korpela and A Ma¨yra¨-Ma¨kinen, Valio Ltd, Finland 11.1 Introduction 229
11.2 Composition of milk 229
11.3 Fermented milk products 231
11.4 What do we mean by functional dairy products? 233
11.5 Examples of functional dairy products: gastrointestinal health and general well-being 234
Trang 1111.6 Examples of functional dairy products: cardiovascular health 238 11.7 Examples of functional dairy products: osteoporosis and
other conditions 241
11.8 Future trends 242
11.9 Sources of further information and advice 243
11.10 References 244
12 Developing and approving health claims for functional dairy products 246
J Snel and R van der Meer, NIZO Food Research, The Netherlands 12.1 Introduction 246
12.2 The body’s defence mechanisms 247
12.3 In vitro studies 249
12.4 Animal studies 251
12.5 Human studies 252
12.6 Making health claims 254
12.7 Future trends 255
12.8 Sources of further information and advice 256
12.9 References 257
Part II New technologies to improve quality 261
13 On-line measurement of product quality in dairy processing 263
G Ellen and A J Tudos, NIZO Food Research, The Netherlands 13.1 Introduction 263
13.2 On-line measurement of physical parameters 265
13.3 Measuring product composition 269
13.4 On-line microbiological testing 279
13.5 Monitoring fouling and cleaning-in-place 280
13.6 Future trends 283
13.7 Sources of further information and advice 287
13.8 References 288
14 Rapid on-line analysis to ensure the safety of milk 292
A Amine, Universite´ Hassan II-Mahammedia, Morocco and L Micheli, D Moscone and G Palleschi, Universita` di Roma `Tor Vergata’, Italy 14.1 Introduction 292
14.2 Monitoring contamination during milking: faecal contamination and mycotoxins 294
14.3 Measuring the effectiveness of heat treatment 299
14.4 Future trends 306
14.5 References 306 viii Contents
Trang 1215 High-pressure processing to improve dairy product quality 310
W Messens, Agricultural Research Centre Ghent, Belgium and J Van Camp and K Dewettinck, Ghent University, Belgium 15.1 Introduction: high-pressure principles and technologies 310
15.2 The effects of high pressure on nutritional and other qualities in milk 311
15.3 The effects of high pressure on bacteria and enzymes 314
15.4 The effects of high pressure on milk proteins 316
15.5 The effects on other properties of milk 317
15.6 The effects on cheese and yoghurt-making properties of milk 319 15.7 High-pressure treatment of cheese 321
15.8 Future trends 325
15.9 Sources of further information and advice 325
5.10 References 326
16 Optimising product quality and process control for powdered dairy products 333
R E M Verdurmen and P de Jong, NIZO Food Research, The Netherlands 16.1 Introduction: evaporation and drying processes 333
16.2 Quality criteria for dairy-based powders 340
16.3 Modelling quality 347
16.4 Process and product control 353
16.5 Ensuring process safety 359
16.6 Sources of further information and advice 362
16.7 References 363
17 Separation technologies to produce dairy ingredients 366
G Bargeman, Akzo Nobel Chemicals bv, The Netherlands 17.1 Introduction 366
17.2 Separation technologies 368
17.3 Isolation of ingredients 374
17.4 Developments in separation technology 385
17.5 Sources of further information and advice 387
17.6 References 387
18 The use of dissolved carbon dioxide to extend the shelf-life of dairy products 391
C R Loss and J H Hotchkiss, Cornell University, USA 18.1 Introduction: factors limiting the shelf-life of dairy products 391
18.2 The effects of CO2on bacterial growth 391
18.3 The effects of CO2on raw milk quality 396
18.4 The effects of CO2on dairy product quality 399
Trang 1318.5 Bactericidal and sporicidal effects of dissolved CO2during
thermal processing 406
18.6 Conclusions 410
18.7 References 410
Part III Cheese manufacture 417
19 Acceleration of cheese ripening 419
V K Upadhyay and P L H McSweeney, University College Cork, Ireland 19.1 Introduction 419
19.2 Accelerating cheese ripening: elevated temperature 421
19.3 Addition of exogenous enzymes or attenuated starters 422
19.4 Use of adjunct cultures 431
19.5 Genetic modification of starter bacteria 433
19.6 High-pressure technology 434
19.7 Enzyme-modified cheeses as flavourings 437
19.8 Future trends 440
19.9 Acknowledgement 441
19.10 Sources of further information and advice 441
19.11 References 441
20 Non-starter lactic acid bacteria (NSLAB) and cheese quality 448
T P Beresford, Dairy Products Research Centre, Ireland 20.1 Introduction 448
20.2 Bacteria comprising the NSLAB complex 450
20.3 NSLAB in different cheese varieties 452
20.4 The source of NSLAB in cheese 454
20.5 The growth of NSLAB in cheese 455
20.6 The influence of NSLAB on cheese quality 457
20.7 Selection of NSLAB adjuncts for quality improvement of cheese 461
20.8 Conclusions 463
20.9 References 463
21 The production of smear cheeses 470
W Bockelmann, BafM, Germany 21.1 Introduction: smear-ripened cheese varieties 470
21.2 Production and ripening 472
21.3 Developing ripening cultures 477
21.4 Conclusions and future trends 488
21.5 Sources of further information and advice 489
21.6 References 489
x Contents
Trang 1422 Flavour formation in cheese 492
W J M Engels, J E T van Hylckama Vlieg and G Smit, NIZO Food Research, The Netherlands 22.1 Introduction 492
22.2 Amino acid conversion 493
22.3 Amino acid catabolism 496
22.4 Methionine catabolism 499
22.5 Branched-chain and aromatic amino acid conversion 501
22.6 Conversion of other amino acids 503
22.7 Natural biodiversity and tailor-made starter cultures 504
22.8 Future trends 505
22.9 References 507
Part IV Appendix 513
23 Improving the nutritional quality of milk 515
D I Givens and K J Shingfield, The University of Reading, UK 23.1 Introduction 515
23.2 Factors affecting milk protein content 516
23.3 Factors affecting milk fat content 518
23.4 Future trends 526
23.5 References 527
Index 532
Trang 15Milk and the range of dairy products derived from milk have long been central
to diet in both developed and developing countries Some dairy processingtechnologies such as fermentation have been used for thousands of years.Building on this long lasting foundation, the dairy processing industry continues
to be at the forefront of innovation in the food industry This important newcollection sums up some of the most important recent developments
Part I considers key aspects of safety and quality Chapter 2 provides afoundation by summarising current knowledge about the major constituents ofmilk The following chapter discusses how factors such as breed and husbandrypractices on the farm influence milk composition The next three chapters focus
on safety, covering hygienic practices on the farm, developments inpasteurisation and sterilisation technologies, and the growing use of modelling
to improve these techniques whilst retaining milk quality A final group ofchapters in Part I consider key aspects of dairy product quality There arediscussions of the latest research on the control of flavour in milk and otherdairy products, improving texture in fermented dairy products, controllingstability and shelf-life, and testing the authenticity of milk and milk products.Building on the traditional nutritional importance of milk, the final two chaptersconsider the new generation of functional dairy products
The second part of the book reviews the range of new technologies thathave emerged recently to improve dairy product quality The first two chapterslook at on-line techniques to monitor and control various aspects of milk safetyand quality They are then followed by chapters on extending the shelf-life ofdairy products through such techniques as high pressure processing, the
1
Introduction
G Smit, NIZO Food Research, The Netherlands
Trang 16production of powdered dairy products and the use of carbon dioxide There isalso a chapter on developments in separation techniques to maximise returns
by producing a wide range of dairy ingredients The final part of the bookconsiders key developments in improving flavour and other qualities in cheesemanufacture
The quality of dairy products, e.g taste, texture, health and safety, as perceived
by the consumer should be the prime and ultimate driver for the dairy industry Thenew developments described in this book will certainly add to their achievement
Trang 17Part I
Dairy product safety and quality
Trang 182.1 Introduction
Milk and dairy products are major components of the human diet in Westerncountries, providing about 30% of dietary proteins and lipids and about 80% ofdietary calcium Current annual production of milk is 600 106 tonnes, ofwhich 85%, 11%, 2% and 2% are bovine, buffalo, caprine and ovine,respectively Although some raw milk is still consumed, the vast majority ofmilk is processed to at least some extent Liquid (beverage) milk is a major fooditem in all developed dairying countries, representing 40% of total milkproduction The remainder is processed into one of several thousand products –the dairy industry is probably the most diverse and flexible sector of the foodindustry The flexibility of milk as a raw material resides in the chemical andphysico-chemical properties of its constituents, many of which are unique Theprincipal constituents of milk can be modified by enzymatic, chemical and/orphysical methods, permitting the production of new products However, theconcentrations and properties of milk constituents are variable and hence theprocessability of milk and the properties of dairy products are inconsistent,although much of this variability can be eliminated by modern technology,which exploits certain features of milk constituents Today, most milk isprocessed in large, highly mechanized and automated factories, whereconsistency in processing properties is essential The resulting products aredistributed through large wholesale and retail outlets, where consistency is,again, paramount Consumers expect consistency also The consistency expected
by the processor, distributor and consumer can be achieved only if the properties
of milk constituents are understood at the molecular level This chapter willdescribe the principal chemical and physico-chemical properties of the major
2
The major constituents of milk
P F Fox, University College Cork, Ireland
Trang 19constituents of milk, i.e., lactose, lipids, proteins and salts, and variations in theconcentrations and properties of these constituents.
The natural function of milk is to supply the neonatal mammal, of which thereare 4500 species, with its complete nutritional and some of its physiologicalrequirements Because the nutritional requirements are species-specific andchange as the neonate matures, the composition of milk shows very large inter-species differences, e.g., the concentrations of fat, protein and lactose range from
1 to 50%, 1 to 20% and 0 to 10%, respectively, and the concentration of eachchanges during lactation Inter-species differences in the concentrations of many
of the minor constituents are even greater than those of the macro-constituents.Milk from domesticated animals has been used by humans since at least 8000
BC Although sheep and goats were the first domesticated dairy animals, becausethey are more easily managed than cattle, the latter, especially certain breeds of
Bos taurus, are now the dominant dairy animals Total recorded world milk
production is 600 106tonnes per annum, of which85% is bovine, 11% isbuffalo and 2% each is from sheep and goats Small amounts of milk areproduced from camels, mares, reindeer and yaks in certain regions with specificcultural and/or climatic conditions This chapter will concentrate on theconstituents and properties of bovine milk Although the constituents of the milk
of the other main dairy species are generally similar to those of bovine milk,they differ in detail and the technological properties of the milk of these speciesdiffer significantly
Milk is a very flexible raw material from which several thousand types ofdairy products are produced around the world in a great diversity of flavours andforms, including1000 varieties of cheese The proportions of total world milkproduction used for the principal dairy products are: liquid (beverage) milk,
39%; cheese, 33%; butter, 32%; whole milk powder, 6%; skimmed milkpowder, 9%; concentrated milk products, 2%; fermented milk products,
2%; casein, 2%; and infant formulae, 0.3% (The sum value exceeds100%; this is due to ‘double accounting’, e.g., butter and skim milk powder, andthe standardization of fat content, e.g., for liquid milk, cheese, etc.) Thisflexibility and diversity are a result of the properties, many of them unique, ofthe constituents of milk, the principal of which are easily isolated from milk,permitting the production of valuable food ingredients Milk is free of off-flavours, pigments and toxins, which is a very important feature of milk as a rawmaterial for food ingredients
The processability and functionality of milk and milk products aredetermined by the properties and concentrations of its principal constituents:proteins, lipids, lactose and salts Many of the principal problems encounteredduring the processing of milk are caused by variability in the concentrations andproperties of these constituents arising from several factors, including breed,individuality of the animal, stage of lactation, health of the animal, especiallymastitis, and nutritional status Synchronized calving, as practised in NewZealand, Australia and Ireland to avail of cheap grass, has a very marked effect
on the composition and properties of milk (see O’Brien et al., 1999a, 1999b,
6 Dairy processing
Trang 201999c; Mehra et al., 1999) Much of the variability can be offset by
standard-izing the composition of milk or by modifying the process technology Geneticpolymorphism of milk proteins has a significant effect on the concentration andtype of protein in milk The chemical and physical properties of the principalconstituents of milk are well characterized and described, including in thefollowing textbooks: Walstra and Jenness (1984), Wong (1988), Fox (1992,
1995, 1997), Jensen (1995), Fox and McSweeney (1998, 2003) and Walstra et
al (1998).
2.2 Lactose
Bovine milk contains about 4.8% lactose Because lactose is responsible for
50% of the osmotic pressure of milk, which is equal to that of blood and isnearly constant, the concentration of lactose in milk is independent of breed,individuality and nutritional factors but decreases as lactation advances andespecially during mastitic infection, in both cases due to the influx of NaCl fromthe blood
Chemical and physico-chemical properties of lactose
Lactose is a reducing disaccharide comprised of glucose and galactose, linked
by a 1-4-O-glycosidic bond Among sugars, lactose has a number of distinctive
characteristics, some of which cause problems in milk products duringprocessing and storage; however, some of its characteristics are exploited toadvantage
• The aldehyde group on the C-1 of the glucose moiety exists mainly in thehemiacetal form and, consequently, C-1 is a chiral, asymmetric carbon.Therefore, like all reducing sugars, lactose exists as two anomers, and ,which have markedly different properties From a functional viewpoint, themost important of these are differences in solubility and crystallizationcharacteristics: -lactose crystallizes as a monohydrate while crystals of -lactose are anhydrous
• The solubility of - and -lactose in water at 20ºC is 7 g and 50 g per
100 ml, respectively The solubility of -lactose is much more temperaturedependent than that of -lactose and the solubility curves intersect at
93.5ºC
• At equilibrium in aqueous solution, lactose exists as a mixture of and anomers in the approximate ratio 37:63 When an excess of -lactose isadded to water, 7 g per 100 ml dissolve immediately, some of whichmutarotates to give an : ratio of 37:63, leaving the solution unsaturatedwith respect to both - and -lactose Further -lactose dissolves, some ofwhich mutarotates to -lactose Solubilization and mutarotation continueuntil two conditions exist, i.e.,7 g of dissolved -lactose per 100 ml and an : ... 50 000 births
10 Dairy processing
Trang 24Lactose in fermented dairy products
The...
• The cream layer served as an index of fat content and hence of the quality ofmilk to the consumer
16 Dairy processing
Trang 30