Gary Tucker - Essentials of Thermal Processing

1 Cover

2 Title Page Essentials of Thermal Processing Second Edition Gary Tucker Campden BRI, Gloucestershire, UK Susan Featherstone Safe Food Consulting, Cape Town, South Africa

3 Copyright Page

4 Preface

5 Glossary of Terms

6 1 History of Thermal Processing 1.1 A BRIEF HISTORY OF THE SCIENCE AND TECHNOLOGY OF THERMAL PROCESSING 1.2 FOOD MICROBIOLOGY AS A SCIENCE 1.3 PACKAGING FOR HEAT PRESERVED FOODS 1.4 DEVELOPMENTS IN CANNERY EQUIPMENT 1.5 FOOD SAFETY References

7 2 Microbiology of Heat Preserved Foods 2.1 FOOD MICROBIOLOGY 2.2 FACTORS THAT AFFECT THE GROWTH OF MICRO‐ORGANISMS 2.3 DESCRIPTION OF SOME MICRO‐ORGANISMS OF IMPORTANCE TO THERMAL PROCESSING 2.4 RISK OF LEAKER SPOILAGE FROM DAMAGED OR COMPROMISED PACKAGING 2.5 A GUIDELINE FOR IDENTIFYING SPOILAGE IN CANNED FOODS References

8 3 Hurdles to Microbial Growth 3.1 CONTROL OF THE MICRO‐ORGANISM LOADING 3.2 USE OF RESTRICTIVE pH LEVELS 3.3 ANAEROBIC ENVIRONMENT OR MODIFIED ATMOSPHERE ENVIRONMENT 3.4 LOW TEMPERATURES 3.5 DEHYDRATION OR LOW WATER ACTIVITY 3.6 CHEMICAL PRESERVATION 3.7 IRRADIATION 3.8 COMBINATION TREATMENTS References

9 4 Low‐acid Canned Foods 4.1 PRODUCTION OF A THERMALLY PROCESSED FOOD 4.2 F 03 STERILISATION PROCESSES 4.3 COMMERCIAL STERILISATION 4.4 MICRO‐ORGANISM DEATH KINETICS 4.5 LOG REDUCTIONS References

10 5 Acid Foods and Other Pasteurised Products 5.1 BACKGROUND 5.2 PASTEURISATION 5.3 INHIBITORY FACTORS TO MICRO‐ORGANISM GROWTH 5.4 PASTEURISATION VALUE (P‐VALUE) GUIDELINES 5.5 GUIDELINES AND GENERAL RECOMMENDATIONS 5.6 THERMAL PROCESSING OF FRUIT 5.7 THERMAL PROCESSING OF PRODUCTS WITH LOW WATER ACTIVITY 5.8 THERMAL PROCESSING OF CURED MEATS References

11 6 Acidified Foods 6.1 BACKGROUND 6.2 ACIDITY MEASUREMENT USING pH 6.3 ACIDIFICATION OF FOODS 6.4 PROCESSING ACIDIFIED FOODS 6.5 DESIGN OF PASTEURISATION PROCESSES 6.6 HOT FILL AND HOLD PROCESSING 6.7 CRITICAL CONTROL POINTS IN THE PRODUCTION OF ACIDIFIED FOODS References

12 7 Heat Preserved Chilled Foods 7.1 UNDERSTANDING MICROORGANISM BEHAVIOUR 7.2 METHODS OF MANUFACTURE References

13 8 Processing Systems8.1 IN‐PACK PROCESSING: RETORT SYSTEMS 8.2 IN‐LINE PROCESSING: HEAT EXCHANGERS 8.3 NEW THERMAL TECHNOLOGIES References

14 9 Cook Values and Optimisation of Thermal Processes 9.1 MATHEMATICAL ANALYSIS OF COOKING 9.2 SETTING PROCESS TARGETS References

15 10 Process Validation10.1 TEMPERATURE DISTRIBUTION 10.2 HEAT DISTRIBUTION 10.3 HEAT DISTRIBUTION TESTING References

16 11 Process Validation 11.1 SETTING THE TARGET PROCESS VALUE 11.2 SELECTING THE CONDITIONS FOR THE HP STUDY 11.3 LOCATING THE PRODUCT COLD POINT 11.4 PROCESS ESTABLISHMENT METHODS 11.5 PROCESS CALCULATION METHODS References

17 12 Cooling Water Treatment 12.1 CHLORINE 12.2 CHLORINE DIOXIDE 12.3 BROMINE 12.4 OZONE 12.5 ULTRAVIOLET LIGHT 12.6 MEMBRANE FILTRATION References

18 13 Handling Processing Deviations13.1 WHAT CONSTITUTES A PROCESS DEVIATION 13.2 WHAT CAN GO WRONG 13.3 ACTIONS REQUIRED

19 14 Packaging Options for Heat‐Preserved Foods 14.1 METAL CONTAINERS 14.2 CAN CONSTRUCTION AND HANDLING 14.3 GLASS 14.4 PLASTICS, FLEXIBLES, AND LAMINATES References

20 15 Incubation Testing 15.1 PURPOSE OF INCUBATION TESTS 15.2 CAUSES OF SPOILAGE 15.3 DESCRIPTIVE TERMS FOR CANNED FOOD SPOILAGE 15.4 METHODS FOR INCUBATION TESTING 15.5 BIOTESTING References

21 16 Critical Factors in Thermal Processing16.1 BACKGROUND 16.2 KEY ASPECTS OF HYGIENE CONTROL SYSTEMS FOR FOOD PROCESSING (FROM CODEX ALIMENTARIUS) 16.3 IDENTIFYING CRITICAL CONTROL POINTS IN THERMAL PROCESSING References

22 17 Environmental Aspects of Thermal Processing 17.1 LIFECYCLE ASSESSMENT (LCA) 17.2 GREENHOUSE GAS EMISSIONS References

23 Index

24 End User License Agreement

1 Chapter 2 Table 2.1 Nutritional types in bacterial metabolism. Table 2.2 Theoretical increase in population of bacteria under ideal conditio... Table 2.3 Table showing heat resistance characteristics of some food‐related ...Table 2.4 Typical heat resistance of spores of some bacteria.Table 2.5 Most probable cause of spoilage of canned foods.

2 Chapter 3Table 3.1 Selected food preservation techniques and their effect on spoilage ...Table 3.2 Minimum growth temperatures for some pathogenic bacteria (taken fro...Table 3.3 Table showing the water activity of different food products.

3 Chapter 4Table 4.1 Heat resistance data for spoilage micro‐organisms relevant to low‐a...Table 4.2 Process times at 121.1 °C to achieve 12‐log reductions in spores of

4 Chapter 5Table 5.1 pH values of some fruits.Table 5.2 Limiting pH values for growth of micro‐organisms of concern in the ...Table 5.3 Heat resistance data for Bacilli and Clostridia applicable to paste...Table 5.4 Heat resistance data for other bacteria applicable to pasteurised prod...Table 5.5 Heat resistance data for other yeasts and moulds applicable to past...Table 5.6 Suggested P ‐values ( T ref93.3 °C, z 8.9 °C) for fruit and vegetables...Table 5.7 Examples of different water activity food groups.Table 5.8 Micro‐organisms of concern, risks, and their control in heat‐treate...

5 Chapter 6Table 6.1 Table showing recommended criteria for judging whether a pH shift i...Table 6.2 Concentration of [H 3O +] and [OH −] in various liquid foods at ...Table 6.3 Table of p K afor some weak acids.Table 6.4 Comparative heat resistance of bacteria important to thermally proc...Table 6.5 Table of suggested F ‐values for high acid and acidified products....Table 6.6 Table of proposed process values ( F value) in relation to pH and ca...Table 6.7 Table of limiting pH values below pH 4.5 for growth of micro‐organi...Table 6.8 Thermal processes for acidified foods.Table 6.9 Thermal process lethalities for acidified foods.Table 6.10 Hot fill and hold process and centre container temperature recomme...

6 Chapter 7Table 7.1 Heat resistance of psychrotrophic C. botulinum .Table 7.2 Heat resistance of B. cereus spores.Table 7.3 Levels of microorganisms in the raw ingredients of a prawn makhani ...

7 Chapter 9Table 9.1 Kinetic factors for vitamin destruction.Table 9.2 Kinetic factors for enzyme destruction.Table 9.3 Kinetic factors for pigment destruction.Table 9.4 Kinetic factors for colour changes.Table 9.5 Kinetic factors for texture changes.Table 9.6 Effect on F 0and C ‐values of increasing the product temperature.Table 9.7 Process temperatures and hold times that result in a minimum botuli...Table 9.8 Process temperatures and times that achieve P ‐value of 10 minutes at...Table 9.9 Process temperatures and times that achieve F 03 end of heating, toge...

8 Chapter 10Table 10.1 Approximate values for the external heat transfer coefficient ( h o)...Table 10.2 Approximate values for the x / k term in Equation (10.5) and resistan...Table 10.3 Approximate values for the internal heat transfer coefficient ( h i)...Table 10.4 Methods used in different retorting systems to ensure good heat di...

9 Chapter 11Table 11.1 Possible marker organisms for use with microbiological log reducti...Table 11.2 Key attributes of the Bacillus amyloliquefaciens α‐Amylase TTI.

10 Chapter 12Table 12.1 Comparing the 2‐ and 3‐chemical method systems for the formation o...

11 Chapter 13Table 13.1 Examples of the more common process deviations experienced by cann...

12 Chapter 14Table 14.1 Table of some plastics used for food packaging and their melting p...

13 Chapter 15Table 15.1 Causes of canned food spoilage.Table 15.2 Required sample size to be 95% sure of finding a defective contain...Table 15.3 Recommended temperatures and times for incubation testing.