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Biofilms in the Dairy Industry

Biofilms in the Dairy Industry

Koon Hoong Teh (Editor), Steve Flint (Editor), John Brooks (Editor), Geoff Knight (Editor)

ISBN: 978-1-118-87623-7

Jun 2015

288 pages

$160.99

Description

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.

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 General characteristics of biofilms 82

5.6.2 Cows 82

5.6.3 Milking equipment and raw milk storage tanks 83

5.6.4 Raw milk tanker 84

5.7 Conclusion 85

References 86

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

6.6.1 Influence of heat 105

6.6.2 Influence of cleaning and sanitation 107

6.7 Conclusion 109

References 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

7.2.1 Geobacillus 113

7.2.2 Anoxybacillus flavithermus 114

7.2.3 Bacillus licheniformis 114

7.3 Spoilage by thermophilic bacilli 114

7.4 Bacterial endospores 115

7.4.1 Spore structure and resistance 115

7.4.2 Sporulation 117

7.4.3 Germination 117

7.5 Enumeration of thermophilic bacilli 118

7.5.1 Viable plate counts 119

7.5.2 Rapid methods 119

7.6 Characterisation and identification of thermophilic bacilli 120

7.6.1 Molecular]based typing methods 121

7.7 Biofilm formation by thermophilic bacilli 122

7.7.1 Attachment of cells and spores to surfaces 122

7.7.2 Biofilm development 123

7.7.3 Spore development within biofilms 125

7.8 Thermophilic bacilli in dairy manufacturing 125

7.8.1 Thermophilic bacilli in raw milk 125

7.8.2 Milk powder manufacturing 125

7.8.3 Thermophilic bacilli in other dairy processes 126

7.9 Control of thermophilic bacilli 127

7.9.1 Cleaning]in]place 127

7.9.2 Other control methods 128

References 129

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

8.5.1 Membrane surface characteristics and biofilm formation 141

8.5.2 Other factors 143

8.6 Biofilm structure 144

8.6.1 Models and bioreactors for biofilm study 144

8.7 Investigation of persistent biofilms on UF membranes 145

8.7.1 Attachment of Klebsiella isolates to UF membranes 146

8.7.2 Removal of Klebsiella biofilms from membranes 148

8.8 Other isolates from WPCs 148

8.9 Conclusion 149

References 150

9 Pathogen Contamination in Dairy Manufacturing Environments 154

9.1 Introduction 154

9.2 Pathogenic bacteria 155

9.2.1 Cronobacter species (formerly Enterobacter sakazakii) 155

9.2.2 Escherichia coli 158

9.2.3 Salmonella species 160

9.2.4 Campylobacter jejuni 162

9.2.5 Bacillus cereus 164

9.2.6 Listeria monocytogenes 167

9.2.7 Staphylococcus 169

9.3 Yeasts and moulds 170

9.4 Preventing contamination of dairy products by pathogenic microorganisms 171

9.4.1 Pathogenic bacteria in raw milk 171

9.4.2 Prevention of contamination at the dairy manufacturing plant 171

References 177

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

References 200

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

11.4.1 Probabilistic models 205

11.4.2 Kinetic models 205

11.4.3 Analytical models 206

11.4.4 Numerical models 207

11.5 Modelling dairy biofilms 208

11.6 Example of biofilm modelling 209

11.6.1 Model laboratory system 210

11.6.2 Pipe model 210

11.6.3 Reactor model 219

11.7 Conclusion 226

References 227

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

12.2.1 Temperature 229

12.2.2 Surface materials 232

12.2.3 Nutrients 232

12.2.4 Water 232

12.2.5 Time 233

12.2.6 Cleaning and sanitation 233

12.2.7 Interactions between bacteria in biofilms 234

12.3 Controlling biofilm development in dairy processing equipment 235

12.3.1 Controlling biofilms with standard cleaning practices 235

12.3.2 Changing equipment design 241

12.4 Controlling biofilm development on environmental surfaces 243

12.4.1 Standard cleaning and sanitation practices 243

12.4.2 Moisture 245

12.4.3 Interactions with other microorganisms 246

12.5 Conclusion 247

References 248

Index 252