| Sinonovacula constricta is one of the consumer favorite shellfish aquatic products with high grade. Along with the rapid development of aquatic products breeding and sustained progress of fresh-keeping technology, mainly to sales mode of fresh Sinonovacula constricta already can not adapt to the rapid growth of harvest output, also can not satisfy the consumer demand of the market conditions in different areas. So for the study of purification processing, frozen preservation and freshness evaluation of Sinonovacila constricta has important theoretical and practical significance.Sinonovaccula constricta must be purified before storage and edible consumption, and its purification effect is closely related to the storage quality. This paper used L9(34) orthogonal experimental design, in order to be able to obtain the best combination of environmental factors to quickly purify Sinonovacula constricta; and drew the freezing curve and temperature change rate curve in different freezing temperature, to determine its freezing point; and as the evaluation index to the change of texture, weight losses and the rate of juice losses, analyzed the influence on Sinonovacula constricta quality in different freezing temperature; then studied effects of different frozen storage processing methods for Sinonovacula constricta qualities, with sensory evaluation. pH, and TVB-N. Aw and texture features as indexes; and analyzed the applicability of texture analysis in Sinonovacula constricta freshness evaluation. Conclusions are as follows:(1) The optimization combination of purification factors was:pH8.20℃,25%o salinity, dark, and purified5hours.(2) Sinonovacula constricta’s freezing point was-1.4℃, and-7℃condition was slow-frozen,-23℃,-31℃and-75℃were quick frozen. The texture features values of Sinonovacula constricta descended after frozen, and the values of quick frozen was closer to the fresh level than slow frozen, and the differences of weight losses and the rate of juice losses were conspicuous also, the lower the freezing temperature, the less the weight losses and the rate of juice losses. But each index values were poorer under the condition of75℃. (3) During frozen storage period, all the Aw and TVB-N values were increased, and all the pH value felt before rose. Hereinto, each index value of-75℃frozen storage group maintained around fresh level; and each index value of-23℃frozen storage group had the maximum changes, however, its TVB-N value was13.2mg/100g at20th weeks, less than the national standard regulations (≤15mg/100g).(4) Sensory score tended to drop off during storage time, especially in the first month down significantly, afterwards the decline curve of-75℃frozen storage group was relatively flat, the decline curve of-23℃frozen storage group was more gently than the group of-75℃frozen before-23℃storage, and the scores respectively were10.4,8.2and7.2at20th weeks, all the groups were edible.Sinonovacula constricta can be stored for5months at least at-23℃.(5) The general trend of three group’s hardness and springiness curves were declining,-75℃frozen storage group decreased more obviously in the first week, the curves remained basic stable later. The curves of other two groups were slightly increasing in the beginning, all showed obviously downward trend later, and the difference of these two groups was not that big. The general trend of three group’s cohesiveness curves were felling rising downward trend. The trend of gumminess and chewiness curves were similar to cohesiveness curves.(6) During frozen storage, texture features values of have great relevance of other freshness indexes such as sensory evaluation, pH and TVB-N. Therefore, the author thinks that texture analysis can be applied to evaluate the freshness of Sinonovacula constricta as a new index. |
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