复合无磷保水剂对反复冻融鲟鱼片理化特性及微观结构的影响

为研究反复冻融条件下复合无磷保水剂对鲟鱼片理化特性及微观结构的影响，以蒸馏水处理作为空白对照组，将碳酸氢钠、柠檬酸钠和山梨糖醇浸泡的鲟鱼片作为处理组，分别进行5 次冻融，并对不同处理组鲟鱼片的解冻损失率、蒸煮损失率、pH值、硫代巴比妥酸（thiobarbituric acid，TBA）值、肌原纤维蛋白溶解度、Ca2＋-ATPase活性、质构特性等指标进行测定，同时比较鲟鱼片的微观组织结构。结果显示，随着冻融次数的增加，鲟鱼片的解冻损失率、蒸煮损失率、TBA值均显著上升（P＜0.05），保水剂速冻处理组上升速率低于缓冻处理组低于空白对照组；各组鱼片pH值均呈现出先下降后升高趋势；水分含量、肌原纤维蛋白溶解度、Ca2＋-ATPase活性、硬度和弹性均显著降低（P＜0.05），保水剂处理组各项指标下降速率均低于空白对照组；组织切片图显示保水剂处理能较好地保持鲟鱼片的微观组织结构。因此，使用由碳酸氢钠、柠檬酸钠和山梨糖醇复合的无磷保水剂对反复冻融条件下鲟鱼片的品质劣变有明显抑制作用。

Effects of Non-phosphate Water-Retaining Agents on the Physicochemical and Microstructure Properties of Sturgeon Fillets Subjected to Repeated Freeze-thaw Cycles

To explore the effects of a phosphorus-free water-retaining agent consisting of sodium bicarbonate, sodium citrate and sorbitol on the physicochemical properties and microstructure of sturgeon slices under repeated freeze-thaw conditions, sturgeon fillets were treated with the water-retaining agent or distilled water as a control before being repeatedly thawed and frozen up to five times. At each cycle, the thawing loss percentage, cooking loss percentage, pH, thiobarbituric acid (TBA) value, myofibrillar protein solubility, Ca2+-ATPase activity and texture characteristics were measured. Meanwhile, the microstructure was examined. The results showed that with the increase in the number of freeze-thaw cycles, the thawing loss percentage, cooking loss percentage and TBA value were significantly increased (P < 0.05), the water-retaining agent treatment plus quick freezing group exhibiting a slower rate of increase in these parameters compared with the water-retaining agent treatment plus slow freezing group and the control group. For all groups, pH decreased first and then increased, water content, myofibrillary protein solubility, Ca2+-ATPase activity, hardness and elasticity significantly decreased (P < 0.05), and the rate of decrease in these parameters was slower in the water-retaining agent treatment groups than in the control group. Cross-sectional images showed that the microstructure of sturgeon fillets could be maintained better by water-retaining agent treatment compared to the blank control group. These findings show that the water-retaining agent can inhibit the quality deterioration of sturgeon fillets under repeated freeze-thaw cycles.