冻结方式对凡纳滨对虾贮藏中组织冰晶及品质的影响

新鲜凡纳滨对虾采用液氮、平板及冰柜冻结结合-20 ℃贮藏,研究不同贮藏时间内其组织冰晶形态与品质变化,以评价出最优的冻结方式。结果显示,随着贮藏时间的延长,平板及冰箱冻结的盐溶性蛋白含量、持水性、感官评分显著降低(p<0.05);而液氮冻结形成的冰晶直径比平板速冻小1/3,比冰箱小1/2;冻结后贮藏180 d其挥发性盐基氮(TVB-N值)≤25 mg/100 g,硫代巴比妥酸值(TBA)仅为0.72 mg/100 g,有效抑制了虾肉肌原纤维蛋白变性及脂肪氧化,能较好维持肌肉组织形态和品质,从而使虾肉的货架期延长至180 d以上。

Effect of different freezing methods on the ice crystals and quality of white shrimp(Penaeus Vannamei)in the storage

Fresh white Shrimp(Penaeus Vannamei)were stored at -20 ℃ for different period after various frozen treatment including liquid nitrogen freezing,plate freezing and refrigerator freezing. The formation of ice crystals in shrimp meat tissues and changes of the meat quality were analyzed in order to evaluate the optimal way of freeze. Results showed that with the extension of storage time,the content of salt-soluble protein and water holding ability and sensory score decreased significantly(p<0.05)in both plate freezing and freezer frozen groups. The ice crystals formed during liquid nitrogen freezing were tinier 1/3 than plate freezing and tinier 1/2 than freezer frozen. After stored for 180 d,the value of TVB-N was ≤25 mg/100 g.The value of TBA was only 0.72 mg/100 g,suggesting the samples treated by liquid nitrogen was in a relative fresh condition because it could maintain the morphology of tissue better. Liquid nitrogen freezing inhibited the protein denaturation and fat oxidation in shrimp effectively in order to prolonging the shelf life more than 180 d and better quality of the shrimp.