不同滞留时间与滞留温度对未冻及冷冻鳙鱼品质变化的影响

以鳙鱼鱼块为研究对象,探讨了冷冻前滞留温度(4、20℃)及滞留时间(1~24 h、1~8 h)对鱼肉p H、感官评分、挥发性盐基氮、剪切力、解冻汁液流失率以及鱼肉显微结构的影响。结果表明:鳙鱼宰后p H变化在8 h(4℃)和4 h(20℃)出现转折,p H在转折点以前下降较快,在转折点以后下降缓慢或轻微上升;感官评分随冻前滞留时间延长出现先慢后快的降低趋势,挥发性盐基氮随时间延长增长先慢后快,转折点均出现在8 h(4℃)和4 h(20℃)。肌纤维间空隙随滞留时间延长增大,纤维排列紊乱。冷冻鳙鱼的解冻汁液流失率随滞留时间延长逐渐增加,p H、感官评分、挥发性盐基氮、剪切力变化趋势与未冻结鱼肉一致,肌纤维排列更加疏松。鳙鱼宰杀后在4℃和20℃下滞留时间分别不超过8 h和4 h,冷冻后鱼肉的品质较好。 

Effect of retention conditions on quality of frozen and fresh bighead carp (Aristichthys nobilis)

It was aimed at studying quality changes in bighead carp muscle. The p H,sensory evaluation,TVB-N,shear force,drip loss and microstructures were analyzed to evaluate the effects of residence time(1~24 h,1~8 h)and retention temperature( 4, 20 ℃) on the quality of steak. The results showed that as residence time extended,the p H decreased rapidly before turning point,which was 8 h at 4 ℃ and 4 h at 20 ℃,after that it decreased slowly or increased slightly. Sensory evaluation,shear force declined while TVB-N value rose gradually. Furthermore,all indexes except p H,sensory evaluation and shear force changed more rapidly after turning point. The microstructure was altered obviously as residence time extended,as indicated by increased space between fibers,loose structure,and so on. Drip loss of frozen fish increased with the increasing residence time. The same trends of other indexes appeared in frozen fish along with those unfrozen,and more decomposition of muscle fibers was observed. In order to obtain high-quality frozen fish,residence time should be less than 8 h(4 ℃) or 4 h(20 ℃).