vilI Contents 8.5 Microbiological methods- the future 14 8.6 References and further reading H.M. Brown and M. H. Hall, Campden and Chorleywood Food 9 Non-microbial factors affecting quality and safety Research association Introduction 9.2 Characteristics of chemical reactions 3 Chemical reactions of significance in chilled foods 4 Characteristics of biochemical reactions 9.5 Biochemical reactions of significance in chilled foods 233 9.6 Characteristics of physico-chemical reactions 38 9.7 Physico-chemical reactions of significance in chilled foods 238 9.8 Non-microbiological safety issues of significance in chilled oods 243 9.9 Conclusions 248 9.10 References Part Iv Safety and quality issues 0 Shelf-life determination and challenge testing 259 G. Betts and L. Everis, Campden and Chorleywood Food Research Association 10.1 Introduction 259 10.2 Factors affecting shelf-life 10.3 Modelling shelf-life 10.4 Determination of product shelf-life 10.5 Maximising shelf-life 278 10.6 Challenge testing 0.7 Future trends 10.8 References 283 11 Microbiological hazards and safe process design 287 M H. Brown. Unilever Research. Sharnbrook 11.1 Introduction 11.2 Definitions 11.3 Microbiological hazards 11.4 Risk classes 11.5 Safe process design 1: equipment and processes 11.6 Safe process design 2: manufacturing areas 316 11.7 Safe process design 3: unit operations for products 323 11.8 Control systems 328 332 11.10 References 3338.5 Microbiological methods – the future . . . . . . . . . . . . . . . . . . . . . . . . 214 8.6 References and further reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214 9 Non-microbial factors affecting quality and safety . . . . . . . . . . . . . 225 H. M. Brown and M. H. Hall, Campden and Chorleywood Food Research Association 9.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225 9.2 Characteristics of chemical reactions . . . . . . . . . . . . . . . . . . . . . . . . 226 9.3 Chemical reactions of significance in chilled foods . . . . . . . . . . 226 9.4 Characteristics of biochemical reactions . . . . . . . . . . . . . . . . . . . . . 231 9.5 Biochemical reactions of significance in chilled foods . . . . . . 233 9.6 Characteristics of physico-chemical reactions . . . . . . . . . . . . . . . . 238 9.7 Physico-chemical reactions of significance in chilled foods . 238 9.8 Non-microbiological safety issues of significance in chilled foods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243 9.9 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248 9.10 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248 Part IV Safety and quality issues 10 Shelf-life determination and challenge testing . . . ............... 259 G. Betts and L. Everis, Campden and Chorleywood Food Research Association 10.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259 10.2 Factors affecting shelf-life . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260 10.3 Modelling shelf-life . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 268 10.4 Determination of product shelf-life . . . . . . . . . . . . . . . . . . . . . . . . . . 270 10.5 Maximising shelf-life . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278 10.6 Challenge testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279 10.7 Future trends . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283 10.8 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283 11 Microbiological hazards and safe process design ............... 287 M. H. Brown, Unilever Research, Sharnbrook 11.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287 11.2 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 290 11.3 Microbiological hazards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 304 11.4 Risk classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 307 11.5 Safe process design 1: equipment and processes . . . . . . . . . . . . . 308 11.6 Safe process design 2: manufacturing areas . . . . . . . . . . . . . . . . . 316 11.7 Safe process design 3: unit operations for decontaminated products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 323 11.8 Control systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 328 11.9 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332 11.10 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333 viii Contents