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In recent years, the formation and impacts of biofilms on dairy manufacturing have been studied extensively, from the effects of microbial enzymes produced during transportation of raw milk to the mechanisms of biofilm formation by thermophilic spore-forming bacteria. The dairy industry now has a better understanding of biofilms and of approaches that may be adopted to reduce the impacts that biofilms have on manufacturing efficiencies and the quality of dairy products. Biofilms in the Dairy Industry provides a comprehensive overview of biofilm-related issues facing the dairy sector. The book is a cornerstone for a better understanding of the current science and of ways to reduce the occurrence of biofilms associated with dairy manufacturing. The introductory section covers the definition and basic concepts of biofilm formation and development, and provides an overview of problems caused by the occurrence of biofilms along the dairy manufacturing chain. The second section of the book focuses on specific biofilm-related issues, including the quality of raw milk influenced by biofilms, biofilm formation by thermoduric streptococci and thermophilic spore-forming bacteria in dairy manufacturing plants, the presence of pathogens in biofilms, and biofilms associated with dairy waste effluent. The final section of the book looks at the application of modelling approaches to control biofilms. Potential solutions for reducing contamination throughout the dairy manufacturing chain are also presented. Essential to professionals in the global dairy sector, Biofilms in the Dairy Industry will be of great interest to anyone in the food and beverage, academic and government sectors. This text is specifically targeted at dairy professionals who aim to improve the quality and consistency of dairy products and improve the efficiency of dairy product manufacture through optimizing the use of dairy manufacturing plant and reducing operating costs.
List of contents
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
References 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
2.3.1 Role of surface charge in relation to the abiotic surface and bacterial cell 19
2.3.2 Hydrophobic interactions 20
2.3.3 Role of carbohydrates in attachment 21
2.3.4 Teichoic acids, eDNA and cell attachment: Are we missing something? 22
2.4 Role of the abiotic surface in attachment 23
2.4.1 Are all abiotic surfaces created even? 23
2.4.2 Surface modification and ion impregnation of stainless steel to reduce cell attachment 25
2.4.3 Surface roughness and microtopography 25
2.5 Staphylococcus and attachment, an example: Surface proteins implicated in cell attachment to abiotic surfaces 27
References 29
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
References 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
4.2.1 Psychrotrophs 49
4.2.2 Mesophiles 50
4.2.3 Thermodurics 50
4.2.4 Thermophiles 51
4.3 Effects of biofilms on food safety 51
4.3.1 Bacillus cereus 51
4.3.2 Listeria monocytogenes 52
4.3.3 Cronobacter sakazakii 53
4.4 Effects of biofilms on spoilage 53
4.5 Effects of biofilms on processing efficiency 55
4.5.1 Effects of fouling and biofilms on heat transfer and flow rates 56
4.5.2 Cleaning 57
4.5.3 Corrosion 58
4.6 Conclusion 59
References 60
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
5.4.1 In Europe 67
5.4.2 In the United States 68
5.4.3 In New Zealand 68
5.5 Microbial profile of raw milk and its effect on the dairy industry 69
5.5.1 Spoilage microorganisms in raw milk 70
5.5.2 Foodborne pathogens 76
5.5.3 Beneficial bacteria 80
5.6 Biofilms at dairy farms 82
5.6.1 Gene
About the author
Dr Koon Hoong Teh graduated from Massey University, Palmerston North, New Zealand, majoring in food technology.
Steve Flint is Professor of Food Safety and Microbiology and director of the Food Division of the School of Food and Nutrition at Massey University, Palmerston North, New Zealand.
John Brooks is Adjunct Professor of Food Microbiology at Auckland University of Technology, Auckland, New Zealand, and microbiology consultant at microTech Services Limited, Ashhurst, New Zealand.
Geoff Knight is a food microbiologist, principal consultant for Food Process Hygiene Solutions, Melbourne, Victoria, Australia.
