chapter  22
28 Pages

- Combination Treatment of Pressure and Mild Heating

Hydrostatic pressure (HP) was ƒrst applied to sterilization of milk as a food processing method over a century ago.1 Since that time, many researchers have experimented on the effects of HP on microorganisms, denaturation of protein, enzymatic reaction, and so on. In particular, a large amount of information about microorganisms such as sterilization, spore germination, and growth inhibition has been accumulated for more than a century. Various techniques were developed from these HP fundamental studies, and some of them have already been put into practice as innovative food processing methods. In addition, the HP treatment combined with heating can not only enforce the effectiveness of the HP treatment and the heating treatment but also lead to the development of innovative techniques. For example, Okazaki and Shigeta have developed two techniques, that is, a pressure-shucked oyster (PSO) machine2 and a microbe-controlling instrument by HP.3 These techniques of HP are considerably affected by temperature. The magnitude of necessary pressures

22.1 Introduction .......................................................................................................................... 583 22.2 Pressure-Shucked Oyster ...................................................................................................... 584

22.2.1 Shucking Machine by HP ......................................................................................... 585 22.2.2 Quality of PSOs ........................................................................................................ 586 22.2.3 Advantages of PSOs ................................................................................................. 587

22.3 Autolysis of Unsalted Fish Protein under Pressurization ..................................................... 587 22.3.1 Autolysis Condition under HP .................................................................................. 588 22.3.2 Behavior of Microorganisms during Autolysis Condition under HP ....................... 590 22.3.3 Quality of PAE.......................................................................................................... 591 22.3.4 Free Amino Acid Component of PAE ...................................................................... 592 22.3.5 Application of Other Marine Materials of Autolysis under Pressurization.............. 593

22.4 Inactivation of Bacterial Spores by Pressure-Assisted Heating ........................................... 595 22.4.1 Compact Pressure Vessel for Pressure Treatment .................................................... 595 22.4.2 Combination of Elevated Temperature and High Hydrostatic Pressure ................... 596 22.4.3 Combination of Mild Heating and Moderate HP-Induced Germination

of Bacterial Spores .................................................................................................... 601 22.4.4 Inžuence of Environmental Factors on Moderate HP-Induced Germination ..........603