About the Editors xi
List of Contributors xiii
Foreword xv
Preface to the Technical Series xvii
Preface xix
Acknowledgements xxi
1 Introduction to Biofilms: Definition and Basic Concepts 1
1.1 Definition of biofilms 1
1.2 Importance of biofilms in the dairy industry 2
1.3 Biofilm formation 3
1.4 Biofilm structure 5
1.5 Composition of the EPS 6
1.6 Composition of the biofilm population 7
1.7 Enhanced resistance of cells within biofilms 9
1.8 Controlling biofilms 10
1.9 Emerging strategies for biofilm control 11
1.10 Conclusion 12
2 Significance of Bacterial Attachment: A Focus on the Food Industry 17
2.1 Introduction: The importance of bacterial attachment in biofilm development 17
2.2 Conditioning films and bacterial footprints: The importance of conditioning films and bacterial footprints in cell attachment 17
2.3 Bacterial outer surface and attachment 19
2.4 Role of the abiotic surface in attachment 23
2.5 Staphylococcus and attachment, an example: Surface proteins implicated in cell attachment to abiotic surfaces 27
3 The Effect of Milk Composition on the Development of Biofilms 36
3.1 Introduction 36
3.2 Milk composition 37
3.3 Influence of organic molecules (protein and lipid) on the development of biofilms in the dairy industry 38
3.4 Protein and lipid molecules reduce attachment of bacteria to surfaces 38
3.5 Effect of ions on the development of biofilms of thermophilic bacilli 40
3.6 Conclusion 46
4 Overview of the Problems Resulting from Biofilm Contamination in the Dairy Industry 49
4.1 Introduction 49
4.2 Microbiological flora associated with dairy manufacturing 49
4.3 Effects of biofilms on food safety 51
4.4 Effects of biofilms on spoilage 53
4.5 Effects of biofilms on processing efficiency 55
4.6 Conclusion 59
5 Raw Milk Quality Influenced by Biofilms and the Effect of Biofilm Growth on Dairy Product Quality 65
5.1 Introduction 65
5.2 Composition of raw milk 66
5.3 Measurement of raw milk quality 66
5.4 Regulations and guidelines for the production of raw milk 67
5.5 Microbial profile of raw milk and its effect on the dairy industry 69
5.6 Biofilms at dairy farms 82
5.7 Conclusion 85
6 Thermoresistant Streptococci 99
6.1 Characteristics of Streptococcus thermophilus and S. macedonicus 99
6.2 Biofilms of thermoresistant streptococci in dairy manufacturing equipment 99
6.3 Attachment of thermoresistant streptococci to surfaces 101
6.4 The role of cell surface proteins in attachment of thermoresistant streptococci 103
6.5 Biofilm growth 104
6.6 Strategies to control thermoresistant streptococci 105
6.7 Conclusion 109
7 Thermophilic Spore?]Forming Bacilli in the Dairy Industry 112
7.1 Introduction 112
7.2 Thermophilic spore?]forming bacilli of importance to the dairy industry 112
7.3 Spoilage by thermophilic bacilli 114
7.4 Bacterial endospores 115
7.5 Enumeration of thermophilic bacilli 118
7.6 Characterisation and identification of thermophilic bacilli 120
7.7 Biofilm formation by thermophilic bacilli 122
7.8 Thermophilic bacilli in dairy manufacturing 125
7.9 Control of thermophilic bacilli 127
8 Biofilm Contamination of Ultrafiltration and Reverse Osmosis Plants 138
8.1 Introduction 138
8.2 Ultrafiltration and reverse osmosis membranes 139
8.3 Membrane configuration and materials 140
8.4 Crossflow and biofouling 140
8.5 Biofilm development 141
8.6 Biofilm structure 144
8.7 Investigation of persistent biofilms on UF membranes 145
8.8 Other isolates from WPCs 148
8.9 Conclusion 149
9 Pathogen Contamination in Dairy Manufacturing Environments 154
9.1 Introduction 154
9.2 Pathogenic bacteria 155
9.3 Yeasts and moulds 170
9.4 Preventing contamination of dairy products by pathogenic microorganisms 171
10 Biofilm Issues in Dairy Waste Effluents 189
10.1 Introduction 189
10.2 Overview of dairy effluent treatment 190
10.3 Dairy farm waste treatment 192
10.4 Composition of biofilms 193
10.5 Application of biofilms in dairy wastewater treatment 195
10.6 Irrigation systems 196
10.7 Controlling biofilms in waste treatment systems 198
10.8 Conclusion 199
11 Biofilm Modelling 203
11.1 Introduction 203
11.2 What is a model? 203
11.3 Why construct a model? 204
11.4 Types of model available 205
11.5 Modelling dairy biofilms 208
11.6 Example of biofilm modelling 209
11.7 Conclusion 226
12 Biofilm Control in Dairy Manufacturing Plants 229
12.1 Introduction 229
12.2 Factors that influence growth and survival of bacteria in biofilms 229
12.3 Controlling biofilm development in dairy processing equipment 235
12.4 Controlling biofilm development on environmental surfaces 243
12.5 Conclusion 247
References 248
Index 253
