Microbiology in Dairy Processing
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List of contributors xv
Foreword xix
Preface xxi
Acknowledgements xxiii
1 Milk fat components and milk quality 1
Iolanda Altomonte, Federica Salari and Mina Martini
1.1 Introduction 1
1.1.1 Milk fat globules 2
1.1.2 Milk fat and fatty acid composition 4
1.2 Conclusions 7
References 7
2 Spore?]forming bacteria in dairy products 11
Sonia Garde Lopez?]Brea, Natalia Gomez?]Torres and Marta Avila Arribas
2.1 Introduction 11
2.2 The bacterial spore 13
2.2.1 Structure and chemical composition of bacterial spores 14
2.2.1.1 Exosporium 14
2.2.1.2 Spore coat 14
2.2.1.3 Outer spore membrane 15
2.2.1.4 Cortex and germ cell wall 15
2.2.1.5 Inner spore membrane 15
2.2.1.6 The core spore 15
2.2.2 Spore resistance 16
2.2.3 Life cycle of spore?]forming bacteria 17
2.3 Spore?]forming bacteria important for the dairy industry 18
2.3.1 Class Bacilli 18
2.3.1.1 Bacillus genus 19
2.3.1.1.1 Bacillus cereus 19
2.3.1.1.2 Other Bacillus species 20
2.3.1.1.3 Importance of Bacillus spp. in the dairy industry 21
2.3.1.2 Geobacillus and Anoxybacillus genera 24
2.3.1.3 Paenibacillus genus 25
2.3.2 Class Clostridia 25
2.3.2.1 Clostridium botulinum 26
2.3.2.2 Clostridium perfringens 28
2.3.2.3 Clostridium tyrobutyricum and related species 28
2.4 Control strategies to prevent poisoning and spoilage of milk and dairy products by spore?]forming bacteria 30
2.5 Conclusions 31
References 32
3 Psychrotrophic bacteria 37
Milena Brasca, Marilu Decimo, Stefano Morandi, Solimar Goncalves Machado, Francois Bagliniere and Maria Cristina Dantas Vanetti
3.1 Introduction 37
3.2 Sources of psychrotrophic bacteria contamination of milk 38
3.3 Important spoilage psychrotrophic bacteria in milk 42
3.4 Molecular tools to characterize psychrotrophic bacteria 43
3.5 Influence of psychrotrophic contamination of raw milk on dairy product quality 45
3.5.1 Bacterial proteases and proteolytic changes in milk 46
3.5.2 Bacterial lipases and phospholipases and their significance in milk 49
3.6 Regulation of extracellular enzymes 52
3.7 Control of psychrotrophic bacteria and related enzymes 53
3.8 Conclusions 54
References 54
4 Stabilization of milk quality by heat treatments 63
Palmiro Poltronieri and Franca Rossi
4.1 Introduction 63
4.2 Thermal treatments of milk 63
4.2.1 Thermization 63
4.2.2 Pasteurization 64
4.2.3 Grade A pasteurized milk 66
4.3 Milk sterilization 67
4.3.1 Control of proper time/temperature setting for safety of milk and milk products 67
4.4 Diseases associated with unpasteurized milk, or post?]pasteurization dairy?]processing contamination 68
4.5 Conclusions 68
References 68
5 Genomics of LAB and dairy?]associated species 71
Palmiro Poltronieri, Franca Rossi, Cesare Camma, Francesco Pomilio and Cinzia Randazzo
5.1 Introduction 71
5.2 Genomics of lab and dairy?]associated species 71
5.2.1 Next?]generation sequencing of strains, dairy starter genomics and metagenomics 72
5.2.2 Pacific Bioscience single?]molecule real?]time sequencing technology 73
5.2.3 Illumina MySeq and HiSeq 2000 73
5.2.4 Ion Torrent platform 73
5.3 NGS platform applied to sequencing of microbial communities 74
5.3.1 Pangenomics 74
5.3.2 Omic technologies: transcriptomics, proteomics, functional genomics, systems biology 75
5.4 Metabolomics and proteomics 76
5.4.1 Subcellular localisation (SLC): secretion systems for secreted proteins 77
5.4.2 Interactome for cell adhesion and pathogen exclusion 78
5.4.3 Lab peptidome 79
5.5 Comparative genomics of dairy?]associated bacteria: the lactobacillus genus complex, streptococci/lactococci, enterococci, propionibacteria and bifidobacteria 79
5.5.1 Comparative genomics of Lb. rhamnosus and Lb. casei 83
5.5.2 Lb. casei core genome and ecotype differences in dairy adapted strains 84
5.6 Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) in adaptive immunity 84
5.7 Regulation in carbon metabolism 85
5.7.1 Transcriptional and posttranscriptional regulation in carbon metabolism 85
5.7.2 Two?]component systems and phosphorylation in sugar substrate regulation 86
5.7.3 Regulatory RNAs and alternative sigma factors in gene expression 87
5.8 Conclusions 88
References 88
6 Metabolism and biochemistry of LAB and dairy?]associated species 97
Palmiro Poltronieri, Giovanna Battelli and Nicoletta Pasqualina Mangia
6.1 Introduction 97
6.2 Carbohydrate substrates, glycolysis and energy production 98
6.2.1 Pentose phosphate pathway 99
6.2.2 Citrate fermentation 99
6.3 Proteolysis, protein substrates and amino acid availability influencing gene expression 100
6.3.1 Cell?]envelope proteinases: the Prt system 101
6.3.2 Oligopeptide permeases and other transporters for peptides and amino acids 101
6.3.3 Peptidolysis and free amino acids 102
6.3.4 Peptidolysis and catabolite repression 105
6.3.5 Amino acid biosynthesis and auxotrophy 105
6.4 Lipolysis, lipases, esterases 106
6.5 Aroma and flavour products of metabolism 107
6.5.1 Aldehydes, alcohols and carboxylic acids 110
6.5.2 Amino acids as precursor flavour compounds 112
6.6 Nonenzymatic production of flavours 113
6.7 Methods of analysis of flavours in dairy products: HPLC, gas chromatography/ mass analysis (GC/MS) 114
6.8 Natural biodiversity of strains in dairy productions 115
6.9 Conclusions 116
References 117
7 Growth needs and culture media for LAB and dairy?]associated species 123
Giuseppe Blaiotta, Maria Aponte and Palmiro Poltronieri
7.1 Introduction 123
7.2 Established culture media for lactobacilli 123
7.2.1 Rogosa agar 124
7.2.2 MRS medium 125
7.2.3 Skim milk and whey agar 125
7.3 M17 medium for selection and enumeration of lactococci and streptococci 126
7.3.1 St. thermophilus agar 126
7.4 Selective media for lactobacilli 127
7.4.1 MRS vancomycin 127
7.4.2 Additional selective agents 128
7.4.3 MRSV plus selective agents for Lb. casei group enumeration 129
7.4.4 MRS?]salicin, MRS?]sorbitol, MRS?]ribose, MRS gluconate agar 129
7.4.5 MRS?]clindamycin?]ciprofloxacin agar 129
7.4.6 MMV medium for Lb. casei group enumeration 130
7.4.7 MRS containing fructose (MRSF) 130
7.4.8 mMRS?]BPB 131
7.4.9 MRS?]NNLP agar and chromogenic agars for complex communities 131
7.4.10 Homofermentative?]heterofermentative differential medium 131
7.5 Media for the isolation of bifidobacteria 132
7.5.1 MRS?]NNLP agar 133
7.5.2 BSM, WSP, TOS?]MUP 133
7.5.3 MRS?]ABC 134
7.6 Phenotyping 134
7.7 Conclusions 135
References 135
8 LAB species and strain identification 139
Cinzia Randazzo, Alessandra Pino, Koenraad Van Hoorde and Cinzia Caggia
8.1 Introduction 139
8.2 Genotypic fingerprinting methods 140
8.3 Culture?]dependent approaches 142
8.3.1 Random amplification of polymorphic DNA 142
8.3.2 ARDRA and RFLP 143
8.3.3 Ribotyping 143
8.3.4 Repetitive element sequence?]based PCR 144
8.3.5 Amplified fragment length polymorphism 145
8.3.6 Pulsed field gel electrophoresis 145
8.4 Non?]genotypic fingerprinting methods 146
8.5 Culture?]independent approaches 147
8.5.1 Culture?]independent methods for qualitative analysis of dairy foods microbiota 147
8.5.2 Culture?]independent methods for quantitative analysis of dairy foods microbiota 150
8.6 Novel high?]throughput techniques: sequencing and metagenomics 151
8.7 Conclusions 152
References 152
9 LAB strains with bacteriocin synthesis genes and their applications 161
Lorena Sacchini, Giacomo Migliorati, Elisabetta Di Giannatale, Francesco Pomilio and Franca Rossi
9.1 Introduction 161
9.2 Bacteriocins from lab 161
9.3 Potential for use of lab bacteriocins as food preservatives 164
9.4 Bacteriocins produced by dairy lab 165
9.5 Identification of lab?]producing bacteriocins 168
9.6 A novel approach for screening lab bacteriocins 170
9.7 Biotechnological interventions for bacteriocin engineering 171
9.8 Conclusions 172
References 172
10 Starter strains and adjunct non?]starter lactic acid bacteria (NSLAB) in dairy products 177
Paola Dolci and Luca Cocolin
10.1 Introduction 177
10.2 Controlled fermentation 177
10.2.1 Natural versus selected lactic acid bacteria starters 178
10.2.2 Starter strains: selection parameter approaches and strain concept 179
10.2.3 Starter culture formulation 180
10.3 Adjunct non?]starter lactic acid bacteria 181
10.3.1 Biodiversity and adaptation to cheese environment 181
10.3.2 Prospective in industrial application 182
10.3.3 Biopreservation and health benefits 183
10.4 Conclusions 185
References 185
11 Milk Fat: stability, separation and technological transformation 191
Gianluigi Scolari
11.1 Introduction 191
11.1.1 Composition and physical state of milk fat 192
11.1.2 Melting point of milk fat 194
11.2 Physical instability of milk fat 194
11.3 Milk fat separation 195
11.3.1 Flocculation or natural creaming 195
11.3.2 Milk fat separation by centrifugation 197
11.4 Partial coalescence 199
11.4.1 General aspects 199
11.4.2 Barrier against coalescence 201
11.4.2.1 Low molecular mass surfactants 201
11.4.2.2 Large sized surfactants (casein micelle) 202
11.4.2.3 Polymeric surfactants (proteins and polysaccharides) 203
11.4.2.4 Mixed films 203
11.5 Foam in milk and cream 204
11.5.1 General aspects 204
11.5.1.1 Foam formation without surfactants 204
11.5.1.2 Foam formation with surfactants 205
11.5.1.3 Drainage of dispersion liquid in foam 206
11.5.2 Foam from cream containing more than 30% milk fat 207
11.6 Whipped cream and butter 209
11.6.1 Technological factors affecting whipped cream and butter production 209
11.7 Churning process 210
11.7.1 Type of cream 210
11.7.2 Physical (crystallization) and biological maturation of cream before churning 212
11.7.3 Churning technology 215
11.7.4 Continuous churning 216
11.7.5 Moulding and packaging 217
11.8 Conclusions 217
References 218
12 Biological traits of lactic acid bacteria: industrial relevance and new perspectives in dairy applications 219
Diego Mora, Fabio Dal Bello and Stefania Arioli
12.1 Introduction 219
12.2 Selecting fermenting bacteria for their ability to have a respiratory metabolism 220
12.3 Selecting galactose?]positive yogurt cultures: working "against the natural evolution of the species" 221
12.4 Accelerating the milk acidification process by selecting proteinase?]positive strains 222
12.5 Accelerating the milk acidification process by selecting urease?]negative S. thermophilus strains 224
12.6 Protective cultures for dairy applications: "work but please do not grow and do not modify the sensory profile of the product" 225
12.7 Selection of starter culture free of transferable antibiotic?]resistance mechanisms 227
12.8 Conclusions 228
References 229
13 Lactic acid bacteria bacteriophages in dairy products: problems
and solutions 233
Giorgio Giraffa, Miriam Zago and Domenico Carminati
13.1 Introduction 233
13.2 Phage classification 234
13.3 Phage?]host interactions 236
13.4 Sources of contamination 238
13.4.1 Milk and cheese whey 238
13.4.2 Dairy cultures 239
13.4.2.1 The lysogenic state 239
13.5 Phage detection and quantification 240
13.6 Methods to control phage contamination 242
13.6.1 Phage inactivation by physical treatments 242
13.6.2 Phage inactivation by chemical treatments 244
13.6.3 Phage control by biological approaches 245
13.7 Conclusions 246
14 Lactic acid bacteria: a cell factory for delivering functional biomolecules in dairy products 251
Tiziana Silvetti, Stefano Morandi and Milena Brasca
14.1 Introduction 251
14.2 Vitamins 253
14.2.1 Vitamin B2 or Riboflavin 254
14.2.2 Vitamin B9 or Folate 255
14.2.3 Vitamin B12 or cobalamin 256
14.2.4 Vitamin K: menaquinone 257
14.2.5 Other B?]group vitamins 258
14.3 Minerals 258
14.4 Bioactive compounds 261
14.4.1 Anti?]hypertensive peptides 262
14.4.2 Antioxidative peptides 263
14.4.3 Bioactive amines 265
14.4.4 Immune system affecting peptides 267
14.4.5 Opioid peptides 267
14.4.6 Metal?]binding peptides 268
14.4.7 Conjugated linoleic acid and conjugated linolenic acid 268
14.5 Low?]calorie sweeteners 269
14.6 Exopolysaccharides (EPS) 271
14.7 Conclusions 273
References 273
15 Dairy technologies in yogurt production 279
Panagiotis Sfakianakis and Constantina Tzia
15.1 Introduction 279
15.2 Yogurt types 280
15.3 Yogurt manufacturing process 281
15.3.1 Initial treatment of milk 281
15.3.2 Standardization of milk components - fat and SNF content 283
15.3.3 Homogenization 284
15.3.4 Heat treatment 286
15.3.5 Fermentation process 288
15.3.5.1 Monitoring of fermentation process - prediction of fermentation evolution 290
15.3.6 Post?]fermentation processing 292
15.3.6.1 Cooling - addition of additives 292
15.3.6.2 Addition of fruit 292
15.3.6.3 Packaging 294
15.3.7 Quality control of yogurt production 294
15.4 Conclusions 295
References 295
16 Milk protein composition and sequence differences in milk and fermented dairy products affecting digestion and tolerance to dairy products 299
Maria Gabriella Giuffrida, Marzia Giribaldi, Laura Cavallarin and Palmiro Poltronieri
16.1 Introduction 299
16.2 Caseins 301
16.2.1 Gene polymorphisms in ¿?]casein genes 302
16.2.2 Gene polymorphisms in ß?]casein gene 303
16.3 Proteolytic release of bioactive peptides in fermented milk and cheese 304
16.4 Minor milk proteins 305
16.4.1 Lactoferrin 305
16.4.2 ß?]Lactoglobulin (ß?]LG) 306
16.4.3 a?]Lactalbumin (a?]LA) 306
16.5 Proteins with bioactive roles 307
16.6 MFGM-associated proteins 308
16.7 Cow's milk protein allergy (CMPA) 308
16.8 Conclusions 309
References 309
Index 315
