ABSTRACT
CONTENTS 13.1 Introduction ............................................................................................. 348 13.2 Irradiation of Food.................................................................................. 350
13.2.1 Absorbed Doses ........................................................................ 350 13.2.2 Safety and Consumer Acceptance ......................................... 352 13.2.3 Radiation Susceptibility of Microorganisms ........................ 353 13.2.4 Reduction or Elimination of Microorganisms...................... 354
13.2.4.1 Parasite Disinfestation............................................. 354 13.3 Retorting of Liquid Foods with or without Particulates.................. 355
13.3.1 Introduction ............................................................................... 355 13.3.2 Retort Method: Liquid System ............................................... 356
13.3.2.1 Mathematical Treatment......................................... 356 13.3.3 Effect of Mode of Rotation ...................................................... 356
13.3.3.1 Effect of Rotational Speed ...................................... 357 13.3.3.2 Effect of Distance between Can and Axis
of Rotation................................................................. 358 13.3.3.3 Effect of Headspace ................................................. 358 13.3.3.4 Effect of Fluid Viscosity.......................................... 359
13.3.4 Retort Method: Liquid Foods with Particulate.................... 359 13.3.4.1 Mathematical Treatment......................................... 359
13.3.5 Effect of Mode of Rotation ...................................................... 360 13.3.5.1 Effect of Rotational Speed ...................................... 360
13.3.6 Effect of Fluid Viscosity........................................................... 361 13.3.7 Effect of Particle Interaction.................................................... 361 13.3.8 Effect of Particle Properties..................................................... 362 13.3.9 Effect of Particle Size................................................................ 362
13.4 Thermal Inactivation-Aseptic Processing......................................... 362 13.4.1 Historical Aspects of Aseptic Processing ............................. 363 13.4.2 Requirements for Aseptic Processing and Packaging ........ 364 13.4.3 Latest Developments in Aseptic Processing
Research...................................................................................... 364 13.5 Microwave Heating ................................................................................ 366
13.5.1 Theory and Characteristics ..................................................... 367 13.5.2 How Microwaves Produce Heat ............................................ 367 13.5.3 Dielectric Properties of Foods................................................. 368 13.5.4 Microwave Food Processing ................................................... 369
13.5.4.1 Thawing and Tempering ........................................ 370 13.5.4.2 Reheating................................................................... 370 13.5.4.3 Drying........................................................................ 371 13.5.4.4 Cooking ..................................................................... 372 13.5.4.5 Blanching................................................................... 372 13.5.4.6 Baking ........................................................................ 372 13.5.4.7 Sterilization and Pasteurization............................. 372 13.5.4.8 Precooking................................................................. 373
13.5.5 Microwave Food Process Design ........................................... 373 13.5.5.1 Physical Factors........................................................ 374
13.5.6 Microbial Safety with Microwave Heating .......................... 375 13.6 Hydrostatic High-Pressure Processing ............................................... 375
13.6.1 Introduction ............................................................................... 375 13.6.2 Mechanism of HPP................................................................... 376 13.6.3 Microbial Inactivation .............................................................. 377
13.6.3.1 Factors Affecting Microbial Inactivation ............. 378 13.6.4 Combined Processes................................................................. 380
13.6.4.1 Pressure and Temperature ..................................... 380 13.6.4.2 Pressure and Other Processes................................ 382
13.7 Conclusions and Outlook to the Future.............................................. 384 References ........................................................................................................... 386
Food preservation has been a long lasting desire of human beings. The significant development in food preservation started the day fire was discovered by prehistoric humans, which was followed by indigenous methods of food preservation such as pickling, oiling, and salting of different food-types, whether raw or processed. Some of the earlier techniques still prevail and are available in several commercial formats. The major developments in and need for food processing and preservation started during wars when extended shelf life of foods became a necessity. As such, several food processing techniques, such as ready-to-eat food in pouches, aseptic processing of milk and liquid foods with particles, ohmic
or electric resistance heating of foods, were developed to achieve extended shelf life of foods for soldiers in wars. A technology transfer effort occurred for consumers, when consumers started demanding a food product with fresh-like characteristics along with extended shelf life. Over the years, consumers became more and more educated on added food preservatives and their adverse effects on long-term health. This all resulted in advances in research and development and finally led to commercialization of innovative food preservation techniques. This also gave birth to several nonthermal food preservation techniques, of which ultra-high pressure processing has started to see its commercialization since late 1990s. Irradiation is also getting limited acceptability by consumers for several food products. Thermal food preservation techniques are being revisited and are being modified to provide consumers with a variety of food products with the characteristics of home-cooked meals.
