Yeasts in Food

Description

Yeasts play a crucial role in the sensory quality of a wide range of foods. They can also be a major cause of food spoilage. Maximising their benefits whilst minimising their detrimental effects requires a thorough understanding of their complex characteristics and how these can best be manipulated by food processors.

Yeasts in food begins by describing the enormous range of yeasts together with methods for detection, identification and analysis. It then discusses spoilage yeasts, methods of control and stress responses to food preservation techniques. Against this background, the bulk of the book looks at the role of yeasts in particular types of food. There are chapters on dairy products, meat, fruit, bread, soft drinks, alcoholic beverages, soy products, chocolate and coffee. Each chapter describes the diversity of yeasts associated with each type of food, their beneficial and detrimental effects on food quality, methods of analysis and quality control.

With its distinguished editors and international team of over 30 contributors, Yeasts in food is a standard reference for the food industry in maximising the contribution of yeasts to food quality.

Describes the enormous range of yeasts together with methods for detection, identification and analysis
Discusses spoilage yeasts, methods of control and stress responses to food preservation techniques
Examines the beneficial and detrimental effects of yeasts in particular types of food, including dairy products, meat, fruit, bread, soft drinks, alcoholic beverages, soy products, chocolate and coffee

Front Cover 2
Yeasts in Food: Beneficial and Detrimental Aspects 3
Copyright Page 4
Dedication 5
Editors preface 7
Editors and authors 9
Table of Contents 13
Chapter 1. Yeast biodiversity 25
- 1.1 Introduction 25
- 1.2 Developments in yeast systematics 26
- 1.3 Species concepts 29
- 1.4 Phylogeny of yeasts 30
- 1.5 Classification of yeasts 31
- 1.6 Morphology of yeasts 35
- 1.7 Where do yeasts occur 44

Front Cover 2
Yeasts in Food: Beneficial and Detrimental Aspects 3
Copyright Page 4
Dedication 5
Editors preface 7
Editors and authors 9
Table of Contents 13
Chapter 1. Yeast biodiversity 25
- 1.1 Introduction 25
- 1.2 Developments in yeast systematics 26
- 1.3 Species concepts 29
- 1.4 Phylogeny of yeasts 30
- 1.5 Classification of yeasts 31
- 1.6 Morphology of yeasts 35
- 1.7 Where do yeasts occur 44
- 1.8 Appendix: Overview of yeast genera of importance to the food industry 45
- 1.9 References 53
Chapter 2. Detection, enumeration and isolation of yeasts 63
- 2.1 Introduction 63
- 2.2 Sample preparation 64
- 2.3 Dilution 65
- 2.5 lncubation 66
- 2.4 Plating and other methods of enumeration 66
- 2.6 Media 67
- 2.7 Toxicity of media on injured cells 79
- 2.8 Non-traditional and rapid methods 80
- 2.10 Acknowledgement 82
- 2.9 Conclusions 82
- 2.11 References 83
Chapter 3. Methods to identify yeasts 93
- 3.1 Introduction 93
- 3.2 Identification from phenotype – fermentation and growth tests 93
- 3.3 Appearance of colonies, cell shape and filamentation 99
- 3.4 Sexual states and mating tests 100
- 3.5 Nuclear staining 101
- 3.6 DNA based methods for yeast identification 102
- 3.7 Pulsed field electrophoresis (electrophoretic karyotyping) 113
- 3.8 Maintenance and storage of cultures 115
- 3.9 Growth media for yeasts including those for detection, enumeration, and isolation of species from foods and clinical specime 117
- 3.10 References 140
Chapter 4. PCR methods for tracing and detection of yeasts in the food chain 147
- 4.1 Introduction 147
- 4.2 Typing of yeasts by PCR-mediated methods 148
- 4.3 Implementation of PCR based methods in food production lines 156
- 4.4 Methods for yeast detection 158
- 4.5 Conclusions 159
- 4.6 References 160
Chapter 5. Data processing 163
- 5.1 Introduction 163
- 5.2 Identification and classification 165
- 5.3 Yeasts data management and identification systems 182
- 5.4 Conclusion and future 188
- 5.5 References 189
Chapter 6. Spoilage yeasts with emphasis on the genus Zygosaccharomyces 195
- 6.1 Introduction 195
- 6.2 Detrimental aspects of Zygosaccharomyces 196
- 6.3 Physiological background of spoilage by Zygosaccharomyces 198
- 6.4 Specific methods to study spoilage by Zygosaccharomyces 204
- 6.5 Quality control 208
- 6.6 Future prospects and conclusions 209
- 6.7 References 210
Chapter 7. Yeast stress response to food preservations systems 217
- 7.1 Introduction 217
- 7.2 Classical food preservatives 218
- 7.3 Novel food preservation systems 222
- 7.4 Concluding remarks 228
- 7.5 References 229
Chapter 8. Yeasts in dairy products 233
- 8.1 Introduction 233
- 8.2 Yeasts and dairy products 233
- 8.3 Kefyr 234
- 8.4 Cheese 242
- 8.5 Yeasts as spoilage organisms in dairy products 250
- 8.6 Conclusion 253
- 8.7 References 253
Chapter 9. Yeasts in meat and meat products 263
- 9.1 Introduction 263
- 9.2 Yeast biodiversity in meat products 264
- 9.3 Beneficial aspects of yeasts in meat products 269
- 9.4 Detrimental aspects of yeast in meat products 271
- 9.5 Physiological characteristics of yeasts in meat 273
- 9.6 Specific methods for analysis of yeasts in meats 277
- 9.7 Quality control 278
- 9.8 Future prospects and conclusions 280
- 9.9 References 281
Chapter 10. Yeasts in fruit and fruit products 291
- 10.1 Introduction 291
- 10.2 Fruits as a habitat for yeast diversity 291
- 10.3 Beneficial aspects of fruit yeasts 297
- 10.4 Detrimental aspects of fruit yeasts 300
- 10.5 Physiological and biochemical background 300
- 10.6 Specific methods of analysis for fruit-associated yeasts 302
- 10.7 Quality control 303
- 10.8 Future prospects and conclusions 303
- 10.9 References 304
Chapter 11. Yeasts in bread and baking products 313
- 11.1 Introduction 313
- 11.2 Properties of baking yeast 313
- 11.3 Physiological aspects of baking yeast 317
- 11.4 Production of baking yeast 319
- 11.5 Genetic improvement of baking yeast 322
- 11.6 Typing of baking yeast 325
- 11.7 Spoilage yeast of baking products 326
- 11.8 References 327
Chapter 12. Non-alcoholic beverages and yeasts 333
- 12.1 Introduction 333
- 12.2 Yeast biodiversity in non-alcoholic beverages 337
- 12.3 Benefits of yeasts in non-alcoholic beverages 347
- 12.4 Physiological background to yeasts in non-alcoholic beverages 348
- 12.5 Quality control and quality assurance 352
- 12.6 Future prospects and conclusions 354
- 12.7 References 357
Chapter 13. Brewing yeasts 371
- 13.1 Introduction 371
- 13.2 Yeast biodiversity related to brewing 371
- 13.3 Beneficial aspects of brewing yeasts 377
- 13.4 Detrimental aspects of yeasts found in breweries 385
- 13.5 Physiological background of brewing yeast 387
- 13.6 Genetic improvement of brewing yeasts 402
- 13.7 Typing of brewing yeasts 403
- 13.8 Yeast quality control 404
- 13.9 Conclusions 406
- 13.10 References 407
Chapter 14. Wine yeasts 413
- 14.1 Introduction 413
- 14.2 Yeast biodiversity related to grapes and wines fermentations 414
- 14.3 Beneficial aspects of wine yeasts 415
- 14.4 Detrimental effect of wine yeasts 416
- 14.5 Physiological background of wine yeasts 418
- 14.6 Genetic improvement of wine yeasts 422
- 14.7 Typing of wine yeasts 425
- 14.8 Conclusion and future prospect 430
- 14.9 References 431
Chapter 15. Yeasts and soy products 437
- 15.1 Introduction 437
- 15.2 Yeast biodiversity 439
- 15.3 Beneficial aspects of yeasts in fermented soy products 440
- 15.4 Detrimental aspects of yeasts in fermented soy products 443
- 15.5 Salt tolerance of yeasts in soy fermentation 443
- 15.6 Genetic improvement of soy yeasts 447
- 15.7 Prospects and conclusions 448
- 15.8 References 449
Chapter 16. Mixed microbial fermentations of chocolate and coffee 453
- 16.1 Introduction 453
- 16.2 Importance 455
- 16.3 Yeast biodiversity 456
- 16.4 Benefical aspects 461
- 16.5 Detrimental aspects 462
- 16.6 Physiological background 463
- 16.8 Future prospects and conclusions 466
- 16.7 Specific methods to study mixed fermentations 466
- 16.9 References 468
Chapter 17. Traditional fermented products from Africa, Latin America and Asia 475
- 17.1 Introduction 475
- 17.2 Yeast biodiversity related to specific fermented products 475
- 17.3 Beneficial aspects of yeasts in fermentations 484
- 17.4 Detrimental aspects of yeasts in (fermented) foods 490
- 17.5 Physiological key properties 490
- 17.6 Future prospects and conclusions 491
- 17.7 References 493
Chapter 18. Index 499

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