Studies On Grass Carp Slices Treated With Ozone And Its Storage Characteristics

Grass carp slice is nourishing, but it is vulnerable to microbial contamination to corrupt and then its storage is short. Although present technologies can improve qualities of fresh fish slices, they can result in defects such as chemical residues, heat sensitivity, nutrition loss and so on. In this study, grass carp slices were treated with ozone. Subsequently the effects of treatment methods and storage methods on the qualities of grass carp were investigated. Then mechanisms of the ozone preservation were explored. The results were as follows:(1) The appropriate processing condition and treatment on grass carp slice were determined. Pseudomonae was the most popular bacteria in fresh grass carp slices, and Escherichia spp., Aeromonas, Micrococcus spp. and Lactococcus were detected. Ozone could kill Enterobacter spp., Micrococcus spp. and Lactococcus effeciently.The grass carp slice treated with ozone was much better than citric acid leaching group, UV irradiation group and control group. The concentration, temperature and time of ozone had significant effects on qualities of grass carp slices. The optimum treatment was treating the slices with 0.85mg/L ozone at 10℃for 10min. The lethality rate of the grass carp slice treated by ozone was higher than the other groups, and the sensory quality and nutritional quality was better.The first grade shelf life of grass carp slices treated with ozone (-0.5℃) was 15 days, 5 more days than control group.(2) The appropriate storage method of grass carp slice was determined. The microbial compositions of grass carp slices changed during storage. Pseudomonae became less and Lactococcus became more. Package methods and storage temperature had significant effects on qualities of grass carp slices. CO₂ could inhibit arobic bacterial and Pseudomonae. The effect increased with increased concentration of CO₂. The shelf life of slices with 100%CO2 package and vacuum package were over 28 days at -0.5℃. 100%CO₂ package could depress the drop loss rate, and maintain sensory quality and nutritional quality more effectively than vacuum package.(3) The preservation mechanism of zone treatment on grass carp slices was determined. Ozone can destroy membrane permeability of microorganism, lead to death or change growth characteristics of residual microorganism, delay the discomposition of proteins and protect colour and texture efficiently.