冻结速率对河蟹肌肉生化特性的影响

采用5种不同的低温冻结处理方式,即-20℃自然慢冻组、速冻处理组(包括-20、-40、-60℃速冻及液氮速冻),进行鲜活整河蟹的冻结,以-20℃条件下贮藏期内河蟹肌肉p H值、丙二醛(malondialdehyde,MDA)含量、Ca~(2+)-ATPase活力、总巯基(-SH)含量、表面疏水性为指标,研究不同冻结速率对冷冻贮藏河蟹肌肉生化特性的影响。结果表明,随着冻藏时间的延长,河蟹样品的p H值下降、脂肪氧化产物MDA含量先增大后减小、Ca~(2+)-ATPase活力降低、总巯基含量降低、表面疏水性增大,速冻处理组的样品各指标变化趋势明显低于或迟缓于慢冻组,且-60℃和液氮组效果要显著优于-20、-40℃处理组,-60℃和液氮组之间各指标差异不显著。

Effect of Freezing Rate on Biochemical Characteristics of Freshwater Crab Muscle

In this paper, the effect of different freezing methods including slow fridge freezing at ?20 ℃, and rapid freezing at ?20, ?40 and ?60 ℃ and in liquid nitrogen, on biochemical characteristics of freshwater crabs were evaluated in terms of muscle pH and malondialdehyde (MDA) content, and Ca2+-ATPase activity, total sulfhydryl content, and surface hydrophobicity of myofibrillar protein. The results showed that during storage at ?20 ℃, pH, Ca2+-ATPase activity and total sulfhydryl content decreased, MDA content increased firstly and then decreased, and surface hydrophobicity increased continuously. All tested parameters changed more slowly or less significantly in rapidly frozen group than in the slowly frozen one. Freezing at ?60 ℃ and in liquid nitrogen were significantly better than at ?20 ℃ and ?40 ℃. Moreover, there was no significant difference in freezing between ?60 ℃ and in liquid nitrogen.