Biofilms in the Dairy Industry

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.

• About the Editors xiList of Contributors xiiiForeword xvPreface to the Technical Series xviiPreface xixAcknowledgements xxi1 Introduction to Biofilms: Definition and Basic Concepts 11.1 Definition of biofilms 11.2 Importance of biofilms in the dairy industry 21.3 Biofilm formation 31.4 Biofilm structure 51.5 Composition of the EPS 61.6 Composition of the biofilm population 71.7 Enhanced resistance of cells within biofilms 91.8 Controlling biofilms 101.9 Emerging strategies for biofilm control 111.10 Conclusion 122 Significance of Bacterial Attachment: A Focus on the Food Industry 172.1 Introduction: The importance of bacterial attachment in biofilm development 172.2 Conditioning films and bacterial footprints: The importance of conditioning films and bacterial footprints in cell attachment 172.3 Bacterial outer surface and attachment 192.4 Role of the abiotic surface in attachment 232.5 Staphylococcus and attachment, an example: Surface proteins implicated in cell attachment to abiotic surfaces 273 The Effect of Milk Composition on the Development of Biofilms 363.1 Introduction 363.2 Milk composition 373.3 Influence of organic molecules (protein and lipid) on the development of biofilms in the dairy industry 383.4 Protein and lipid molecules reduce attachment of bacteria to surfaces 383.5 Effect of ions on the development of biofilms of thermophilic bacilli 403.6 Conclusion 464 Overview of the Problems Resulting from Biofilm Contamination in the Dairy Industry 494.1 Introduction 494.2 Microbiological flora associated with dairy manufacturing 494.3 Effects of biofilms on food safety 514.4 Effects of biofilms on spoilage 534.5 Effects of biofilms on processing efficiency 554.6 Conclusion 595 Raw Milk Quality Influenced by Biofilms and the Effect of Biofilm Growth on Dairy Product Quality 655.1 Introduction 655.2 Composition of raw milk 665.3 Measurement of raw milk quality 665.4 Regulations and guidelines for the production of raw milk 675.5 Microbial profile of raw milk and its effect on the dairy industry 695.6 Biofilms at dairy farms 825.7 Conclusion 856 Thermoresistant Streptococci 996.1 Characteristics of Streptococcus thermophilus and S. macedonicus 996.2 Biofilms of thermoresistant streptococci in dairy manufacturing equipment 996.3 Attachment of thermoresistant streptococci to surfaces 1016.4 The role of cell surface proteins in attachment of thermoresistant streptococci 1036.5 Biofilm growth 1046.6 Strategies to control thermoresistant streptococci 1056.7 Conclusion 1097 Thermophilic Spore]Forming Bacilli in the Dairy Industry 1127.1 Introduction 1127.2 Thermophilic spore]forming bacilli of importance to the dairy industry 1127.3 Spoilage by thermophilic bacilli 1147.4 Bacterial endospores 1157.5 Enumeration of thermophilic bacilli 1187.6 Characterisation and identification of thermophilic bacilli 1207.7 Biofilm formation by thermophilic bacilli 1227.8 Thermophilic bacilli in dairy manufacturing 1257.9 Control of thermophilic bacilli 1278 Biofilm Contamination of Ultrafiltration and Reverse Osmosis Plants 1388.1 Introduction 1388.2 Ultrafiltration and reverse osmosis membranes 1398.3 Membrane configuration and materials 1408.4 Crossflow and biofouling 1408.5 Biofilm development 1418.6 Biofilm structure 1448.7 Investigation of persistent biofilms on UF membranes 1458.8 Other isolates from WPCs 1488.9 Conclusion 1499 Pathogen Contamination in Dairy Manufacturing Environments 1549.1 Introduction 1549.2 Pathogenic bacteria 1559.3 Yeasts and moulds 1709.4 Preventing contamination of dairy products by pathogenic microorganisms 17110 Biofilm Issues in Dairy Waste Effluents 18910.1 Introduction 18910.2 Overview of dairy effluent treatment 19010.3 Dairy farm waste treatment 19210.4 Composition of biofilms 19310.5 Application of biofilms in dairy wastewater treatment 19510.6 Irrigation systems 19610.7 Controlling biofilms in waste treatment systems 19810.8 Conclusion 19911 Biofilm Modelling 20311.1 Introduction 20311.2 What is a model? 20311.3 Why construct a model? 20411.4 Types of model available 20511.5 Modelling dairy biofilms 20811.6 Example of biofilm modelling 20911.7 Conclusion 22612 Biofilm Control in Dairy Manufacturing Plants 22912.1 Introduction 22912.2 Factors that influence growth and survival of bacteria in biofilms 22912.3 Controlling biofilm development in dairy processing equipment 23512.4 Controlling biofilm development on environmental surfaces 24312.5 Conclusion 247References 248Index 253