The Effect Of Frozen Storage And Thawing Methods On The Quality Of Pelagic Fishery(Loligo Japonica And Coloabis Saira)

Regional and seasonal of distant water fisheries production were very strong, aquatic products with high moisture content and nutrient rich characteristics, so they were suitable for microbial growth and reproduction. Limited by storage and transportation conditions, the quality of fresh aquatic products were not easy to maintain.Therefore, this paper selects the squid(Loligo japonica) and saury(Cololabis saira) two ocean catches as raw materials, in the present work investigations of cooking loss, thawing loss, total volatile basic(TVB-N), salt solubility protein content, sulfhydryl content, Ca2+-ATPase activity, thiobarbituric acid reactive substances(TBARS), organoleptic evaluation and muscular tissue when subjected to frozen storage temperature(-20,-30 and-50℃) and the four methods of thawing(running water thawing, static water thawing, room temperature air thawing and low-temperature air thawing) in pelagic fishery(Loligo japonica and Coloabis saira). To explored the Loligo japonica and Coloabis saira in frozen storage and thawing meat quality variation, the experimental results are as follows:1. Ca2+-ATPase activity and sensory evaluation decreased with the prolongation time at different frozen storage temperature.Meanwhile, salt solubility protein content and sulfhydryl content slight increased at first and decreased later. The TVB-N value and TBARS value increased at frozen storage, regardless of the storage temperature, increasing at a faster rate and higher storage temperature. The rising rate of TVB-N and TBARS value has been showing upward trends at different temperature. The higher the temperature is, the faster the rate of rise. Rate of decline in the quality of frozen Loligo japonica under different temperature conditions and the different was significant. The Loligo japonica quality at-30℃and-50℃ were significantly better than-20℃.Therefore, when Loligo japonica was stored at-30℃ or below, it can keep the quality better.2. Low temperature had the least quality loss and the physicochemical characteristics of Cololabis saira closer to fresh muscle. Cooking loss, TVB-N value and TBARS value was decreased with the increased of frozen storage time and TVB-N value was significantly higher than the other two groups(P<0.01) at-20℃, while there were little difference between-30 and-50 ℃after about 180 days. Frozen storage led to special structure of muscle protein changes, making the protein denaturation, salt solubility protein content and sulfhydryl content were significantly decreased which-20 ℃group decreased at a faster rate. TBARS value of three temperature were significant difference at the end of the frozen time(P<0.05),while frozen Cololabis saira developed slight rancidity at-20℃. Therefore, when Cololabis saira was stored at-30℃ or below, it can keep the quality and save economical efficiency better.3. Four thawing methods of Loligo japonica, room temperature air thawing TVB-N value was the highest, although did not exceed the threshold of the provisions of the state, it has second grade fresh; low-temperature air thawing, the degree of lipid oxidation was low and thawing time was too long. Compared with static water thawing, it had no significant difference(P>0.05); Ca2+-ATPase activity and sulfhydryl content of running water thawing and static water thawing were higher, indicating that protein decomposition rate was low; thawing loss and cooking loss of low-temperature thawing rate were low, sensory evaluation is better,Ca2+-ATPase activity and sulfhydryl content were low.Static water thawing was the ideal thawing by considering the thawing time, economic benefits and factory conditions.4. The thawing time of frozen Coloabis saira were as the following: running water way, static water way, room temperature air thawing way and low-temperature air way. The thawing loss and cooking loss of Coloabis saira thawed by low-temperature air way were the lowest. The hardness value of Coloabis saira thawed by low-temperature air way was significantly higher than those thawed by the other ways(P<0.05). There were no significant differences on the TVB-N value and salt solubility protein content of Coloabis saira among the four thawing ways(P>0.05), while the sulfhydryl content of Coloabis saira thawed by low-temperature air way was lowest. The TBARS values of Coloabis saira thawed by running water way and static water way were higher, and low-temperature air thawing could slow down the rate of fat oxidation. Furthermore, room temperature thawing induced obvious gap between muscle fibers and broken more muscle fiber bundles. Considering the quality control and economic benefits, low-temperature air way is suitable for the thawing of frozen Coloabis saira.