Studies On Application Of Ozone Sterilization Combined With Liquid Nitrogen Freezing On Abalone Processing

In order to improve the quality of the frozen abalone, the best sterilization technology of abalone was studied, the lethal kinetics model between ozone and microorganisms was established, and the quality difference bewteen two freezing treatments, that is liquid nitrogen flash freezing and traditonal freezing, was compared in this paper. Thus, the theoretical foundation of a new techology, which combined ozone sterilizaton with liquid nitrogen freezing, was provided based on the studies above. The experimental results was as follow:1. The results of Ozonated Water (OW)sterilization showed: the ratio of ozone to water is 1:6, which was determined by Single factor method. The best parameters of abalone sterilization by OW were: the concentration of OW was 2.0mg/L, the operating time is 8min, the temperature is 10℃. The quality of abalone was better and the TVB-N value was lower after cold storage with ozone treatment.2. The sterilization effect of four microbes in marine products including S.cerevisiae, Salmonella, E.coli, Vibrio Parahemolyticus in OW was investigated. The mathematical model of the OW concentration (C) on microbe lethality was established and it could be described as a piecewise function . And the critical OW concentration (Cc) and regression coefficient k of the model could be attained. The fitting curve of lethal effect to the OW operating time could be described by establishing a mathematical model of operating time to microbe survival rate,21s = k e ?k t, and the critical OW operating time and regression coefficientk of the model could be attained. By comparison of the critical OW concentration, critical operating time, sensitive constant k and the structure and size of bacterial of these four microbes, the results showed that: the sterilization effect of Gram-negative bacteria was better than Gram-positive bacteria; the OW sterilization effect was relative to the thickness of bacterial cytoderm. 3. The impact of liquid nitrogen quick-frozen and freezing slowly on freezing curve of abalone center meat, physical and chemical properties, sensory quality and quantity of micro-organisms were studied and compared separately. It showed that liquid nitrogen quick-frozen made abalone center drop in temperature rapidly. At the maximal ice crystal production area the temperature had been a downward trend with virtually no stay. In the basic there was no significant difference between thawed abalone meat and fresh abalone meat in the water holding capacity, salt-soluble protein content (EPN) and the sensory parameters. Abalone meat was better than slow freezing abalone meat and the residual micro-organisms significantly reduced.4. In this study, the comparison of the TVB-N values and the changes of colonies of abalone which was processed by ozone combined with frozen in liquid nitrogen and the traditional process of frozen during the 3 months storage, and the sensory evaluation with the method of Triangle different test and Wilcoxon Test of the abalone products were made after storage. The results showed that: the increment of TVB-N value of the frozen Group and the number of colonies are less significantly than the freezing group of abalone, and closer to the quality of the fresh abalone.