New Methods of Food Preservation

The majO.r techniques emplO.yed fO.r fO.O.d preservatiO.n have a 100ng histo'ry O.f use. They include chilling; freezing; drying; curing; cO.nserving; fer­ menting O.r O.therwise acidifying; the additiO.n O.f preservatives; heat­ pasteurisatiO.n and sterilisatiO.n. Newer techniques mO.re-O.r-less derived frO.m these traditiO.nal proce­ dures include the successful applicatiO.n O.f cO.mbinatiO.n. preservatiO.n O.r 'hurdle' methO.ds, vacuum- and mO.dified atmO.sphere-packaging, and cO.ntinuO.us sterilisatiO.n cO.upled to' aseptic packaging. More innO.vative techniques, such as the use O.f iO.nising radiatiO.n, are increasingly being emplO.yed. At the same time, there is a reawakening O.f interest in even mO.re radical apprO.aches. The reaSO.ns fO.r this derive principally from cO.nsumers' requirements fO.r fO.O.ds that are higher in quality, so. less severely prO.ces­ sed; mO.re natural, so. less heavily preserved; nutritiO.nally healthier, so. cO.ntaining less salts, sugars and fats; and, with respect to' fO.O.d pO.isO.ning, with retained, O.r preferably improved, assurance O.f safety.

1 Principles and applications of hurdle technology.- 1.1 Introduction.- 1.2 Examples of the hurdle effect.- 1.2.1 Fermented foods.- 1.2.2 Shelf stable products (SSP).- 1.2.3 Intermediate moisture foods (IMF).- 1.3 Behaviour of microorganisms during food preservation.- 1.3.1 Homeostasis of microorganisms.- 1.3.2 Multi-target preservation of foods.- 1.3.3 Stress reactions and metabolic exhaustion.- 1.4 Total quality of foods.- 1.4.1 Optimal range of hurdles.- 1.4.2 Potential safety and quality hurdles.- 1.4.3 User guide to food design.- 1.5 Application of hurdle technology in less developed countries.- 1.5.1 Fruits of Latin America.- 1.5.2 Dairy product of India.- 1.5.3 Meat products of China.- 1.6 Future potential.- References.- 2 Bacteriocins: natural antimicrobials from microorganisms.- 2.1 Introduction.- 2.1.1 Historical.- 2.2 Bacteriocin structure and function.- 2.2.1 Lantibiotics.- 2.2.2 Small heat-stable bacteriocins.- 2.2.3 Large heat-labile bacteriocins.- 2.3 Genetics of bacteriocins from LAB.- 2.3.1 Genetic organization of bacteriocin operons.- 2.3.2 Genetic location of bacteriocin genes.- 2.4 Application of bacteriocins in food systems.- 2.4.1 Dairy industry.- 2.4.2 Canning industry.- 2.4.3 Meat industry.- 2.4.4 Wine and beer.- 2.4.5 Sauerkraut.- 2.5 Future prospects for bacteriocins.- References.- 3 Natural antimicrobials from animals.- 3.1 Introduction.- 3.2 The phagosome.- 3.3 Antibiotic peptides.- 3.3.1 Biological role.- 3.3.2 Chemical attributes and spectrum of action.- 3.4 Protein amendment and production of antibiotic peptides.- 3.4.1 Iron.- 3.4.2 Avidin.- 3.5 The lactoperoxidase system (LPS).- 3.6 Lysozymes.- 3.7 Prospects.- References.- 4 Natural antimicrobials from plants.- 4.1 Introduction.- 4.2 Phytoalexins.- 4.3 Organic acids.- 4.4 Essential oils.- 4.5 Phenolics, pigments and related compounds.- 4.5.1 Factors affecting antimicrobial action.- 4.6 Modes of action.- 4.7 Health and legislative aspects.- 4.8 Conclusions.- References.- 5 Food irradiation: current status and future prospects.- 5.1 Introduction.- 5.2 Development of national regulations.- 5.3 Technical advantages and limitations of food irradiation.- 5.3.1 Techno-economic advantages.- 5.4 Limitations of food irradiation.- 5.4.1 Technical.- 5.4.2 Infrastructure and economics.- 5.4.3 Consumer concerns.- 5.5 Consumer acceptance of irradiated food.- 5.5.1 Consumer attitude surveys.- 5.5.2 Market testings and retail sales of irradiated food.- 5.6 Commercial applications of food irradiation.- 5.7 International co-operation in the field of food irradiation.- 5.7.1 Co-operation among FAO, IAEA and WHO.- 5.7.2 Co-operation with the Codex Alimentarius Commission.- 5.7.3 Co-operation leading to international trade in irradiated food.- 5.8 Conclusions.- References.- 6 Microwave processing.- 6.1 Introduction.- 6.2 Introduction to microwaves and their interaction with food materials.- 6.2.1 Basics.- 6.2.2 How microwaves heat.- 6.2.3 Power absorption.- 6.2.4 Uniformity of heating.- 6.2.5 Material properties.- 6.3 Microwaves and microorganisms.- 6.3.1 Early work (1940-55).- 6.3.2 Renewal of interest in the 1960s.- 6.3.3 Conclusion.- 6.4 Microwave processing equipment.- 6.4.1 The benefits of microwave processing.- 6.4.2 Current status of microwave processing in food industry applications.- 6.4.3 Microwave patents in preservation.- 6.5 Case histories.- Case history 1 Green tea drying/roasting system with microwave and far infra-red techniques.- Case history 2 Drying of pharmaceuticals.- Case history 3 Pasteurisation of fruit and sugar mixture.- Case history 4 Sterilisation after packaging of pasta products.- Case history 5 Pilot plant microwave sterilizer.- 6.6 The future.- References.- 7 Hydrostatic pressure treatment of food: equipment and processing.- 7.1 Introduction.- 7.2 General description of an industrial high pressure system.- 7.2.1 The high pressure vessel and its closure.- 7.2.2 Pressure generation.- 7.2.3 Temperature control.- 7.2.4 Material handling.- 7.3 Current commercial applications of high pressure technology.- 7.3.1 Isostatic pressing.- 7.3.2 Quartz growing.- 7.3.3 Chemical reactors.- 7.4 Current status of high hydrostatic pressure technology with a view to food processing.- 7.4.1 Introduction.- 7.4.2 HHP food processing conditions: time, temperature and pressure.- 7.4.3 Capacity requirements.- 7.4.4 Fast cycling in combination with three shifts per day, 300 days per year operation.- 7.4.5 Process control.- 7.4.6 Safety.- 7.5 The challenges of the commercial application of high pressure technology in the food industry.- 7.5.1 Technical challenges.- 7.5.2 Economic and commercial challenges.- 7.6 Outlook.- Acknowledgements.- References.- 8 Hydrostatic pressure treatment of food: microbiology.- 8.1 History and key issues of high pressure application.- 8.2 Current applications.- 8.3 Pressure effects of microorganisms.- 8.3.1 Possible mechanisms of action.- 8.3.2 Pressure inactivation of vegetative cells in food systems.- 8.3.3 Pressure effects on bacterial spores.- 8.4 Combination treatments.- 8.5 Conclusions.- Acknowledgements.- References.- 9 Effect of heat and ultrasound on microorganisms and enzymes.- 9.1 Historical perspective.- 9.1.1 Heat inactivation of microorganisms and enzymes.- 9.1.2 Destructive effect of ultrasound waves on microorganisms and enzymes.- 9.2 Destructive effect of combined treatments of heat and ultrasound under pressure: Mano-Thermo-Sonication (MTS).- 9.2.1 Effects of MTS on microorganisms.- 9.2.2 Effect of MTS on enzymes.- 9.3 Conclusions.- References.- 10 Electrical resistance heating of foods.- 10.1 Introduction.- 10.1.1 The thermal sterilisation of foods.- 10.1.2 Heat generation: electrical resistance heating.- 10.1.3 APV Baker ohmic heater.- 10.1.4 Preservation by electrical heating.- 10.2 The physics of electrical heating.- 10.2.1 Governing electrical equations.- 10.2.2 Thermal properties of foods.- 10.2.3 Food mixtures: flow and heat generation.- 10.3 Models for electrical heating.- 10.3.1 Electrical conductivity of foods.- 10.3.2 Electrical conductivity of solid―liquid mixtures.- 10.3.3 Flow and heat transfer.- 10.3.4 Holding and cooling systems.- 10.4 Electrically processed foods.- 10.4.1 Frequency effects in electrical processing.- 10.4.2 Enhanced diffusion in electrical processing.- 10.4.3 Differences between diffusion in conventional and electrically processed foods.- 10.5 Conclusions.- Acknowledgements.- References.- Nomenclature.- 11 High-voltage pulse techniques for food preservation.- 11.1 Introduction.- 11.2 Cell count reduction by using electricity: a historical review.- 11.3 The Elsteril Process.- 11.4 The influence of high-voltage pulses on microorganisms.- 11.5 The influence of electric high-voltage pulses on food ingredients.- 11.6 Mathematical modelling of cell count reduction.- 11.7 Conclusions.- References.- 12 Preservation by microbial decontamination; the surface treatment of meats by organic acids.- 12.1 Introduction.- 12.2 Critical control points in carcass contamination.- 12.2.1 Material: the animal.- 12.2.2 Machine: equipment and utensils.- 12.2.3 Method: slaughter and fresh meat processing.- 12.2.4 Man: the slaughter personnel.- 12.3 Organic acids as meat decontaminants.- 12.3.1 The antimicrobial properties of organic acids.- 12.3.2 Factors influencing the efficacy of meat decontamination by acids.- 12.4 Effects of acid treatment on sensory properties.- 12.4.1 Effects on colour.- 12.4.2 Effects on flavour and odour.- 12.4.3 Effects on drip loss.- 12.5 Mode of application of acids; technologies available.- 12.5.1 Spraying and spray cabinets.- 12.5.2 Immersion.- 12.5.3 Other methods.- 12.6 Acceptability of acid treatment.- 12.6.1 Toxicological considerations.- 12.6.2 Legislation and regulations.- 12.7 Conclusions and actions needed.- Acknowledgements.- References.- 13 Advances and potential for aseptic processing.- 13.1 Aseptic technology.- 13.2 Regulatory effects.- 13.3 Aspects of food manufacturing practice.- 13.3.1 Scheduled processes.- 13.4 GMP guidelines.- 13.5 Design and development.- 13.5.1 Food contact surfaces.- 13.5.2 Food process.- 13.5.3 Non-food contact surfaces.- 13.5.4 Decontamination of packaging.- 13.5.5 Aseptic filling zone.- 13.6 Commissioning tests.- 13.7 Manufacturing directive.- 13.8 Economics and market trends.- 13.8.1 Bulk packaging.- 13.8.2 Commodity, added value or niche product?.- 13.9 Conclusions.- References.- 14 Advances in modified-atmosphere packaging.- 14.1 Introduction.- 14.1.1 Role of gases.- 14.2 Market status and potential.- 14.3 Microbiology of MAP.- 14.3.1 Microbial spoilage.- 14.3.2 Microbial safety.- 14.3.3 Clostridium botulinum.- 14.3.4 Other pathogens.- 14.4 Developments in MAP.- 14.4.1 Intelligent packaging.- 14.4.2 Predictive, mathematical modelling.- 14.4.3 Combination treatments.- 14.4.4 Packaging films/equipment.- 14.4.5 Indicators.- 14.5 The future.- Acknowledgement.- References.