不同冷冻方式对淡水鱼品质的影响

Effect of Different Freezing Methods on the Quality of Freshwater Fish

为了研究不同冷冻方式对淡水鱼品质的影响,以鮰鱼、鲈鱼、鳜鱼为研究对象,采用-30℃平板、-80℃冰箱和-80℃液氮分别对鮰鱼、鲈鱼、鳜鱼进行冷冻处理,考察了不同冷冻方式对鮰鱼、鲈鱼和鳜鱼的解冻损失率、加压失水率、蒸煮损失率、pH值、色泽、韧性、微观组织结构、水分分布等指标。结果表明:经过-30℃平板冷冻、-80℃冰箱和-80℃液氮处理后,同种淡水鱼解冻损失率、加压失水率、蒸煮损失率呈现下降趋势,其韧性呈现增大趋势,pH值无显著性变化,细胞间隙呈现下降趋势;对于同种淡水鱼,-30℃平板冷冻组的白度最高,-80℃冰箱和-80℃液氮组间无显著差异(P>0.05);低场核磁共振结果表明,对于同种淡水鱼,相对其他两种冷冻方式,-30℃平板冷冻处理组样品的不可移动水(T22)含量下降,自由水(T23)含量显著升高(P<0.05);对于不同淡水鱼,经同种冷冻方式处理后其相关指标间差异性较小。从冷冻速率和品质考虑,选择-80℃冰箱和-80℃液氮处理更有利于保持淡水鱼的品质。

In order to study the effects of different freezing methods on the quality of freshwater fish,channel catfish,Lateolabrax japonicus and mandarin fish were frozen by plate freezing at 30℃(treatment 1),in a refrigerator at 80℃(treatment 2)or with liquid nitrogen at 80℃(treatment 3).The thawing loss percentage of frozen fish was measured as well as pressure-induced water loss percentage,cooking loss percentage,pH,color,toughness,microstructure,water distribution after thawing.The results showed that the thawing loss rate,pressure-induced water loss percentage and cooking loss percentage as well as the space between cells in each fish species with freezing treatments 1,2 and 3 decreased in that order,whereas the toughness increased.Nevertheless,there was no significant difference in pH among the three treatments.Treatment 1 showed the highest whiteness,yet there was no signi ficant difference between the other two treatments(P>0.05).Low-field nuclear magnetic resonance(NMR)showed that the content of bound water(T22)in each fish species with treatment 1 was decreased compared with the remaining treatments,whereas the content of free water(T23)was significantly increased(P<0.05).For each treatment,there were no signi ficant differences in all parameters investigated among fish species.From the viewpoint of both freezing rate and quality maintenance,freezing in a refrigerator at 80℃and with liquid nitrogen at 80℃were more suitable for freshwater.