速冻温度对罗非鱼片品质的影响

通过测定不同冷冻方式冻罗非鱼片的理化指标,试图找到最优处理方式,并为冻罗非鱼片工厂化生产提供参考。通过设置双螺旋冷冻机不同的冷冻温度(-35℃、-38℃、-41℃、)冻结新鲜罗非鱼片,将冻结后的鱼片置于-18℃的冷库贮藏,每隔7 d对鱼片样品的pH、水分活度(Aw)、质构参数、挥发性盐基氮(TVB-N)等物理及化学指标进行检测并分析结果。数据表明,冷冻温度对鱼片色差值、失水率、硬度有较大影响,且冷冻温度越低,鱼片品质越好,对咀嚼性、弹性、TVB-N影响不大,对pH则无明显影响。综上,在现有加工工艺的冷冻温度波动范围内,选择较低冷冻温度,提高冻结速率可延缓冻罗非鱼片品质劣变速度,故建议企业加工时,将冷冻温度控制在-40℃,冷冻时间控制在40 min以尽可能保持鱼片品质。

Effect of the frozen temperature on the quality of tilapia fillets

This study aims to find the optimal treatment method and provide reference for the industrialized production of frozen tilapia fillets by measuring physical and chemical indicators of frozen tilapia fillets with different freezing methods.Fresh tilapia fillets were frozen by setting different freezing temperatures (-35℃,-38℃,-41℃) of the double-screw chiller.The frozen fillets were stored at-18℃ refrigerator.The pH value,water activity (Aw),texture parameters,volatile base nitrogen (TVB-N) and other physical and chemical indicators of the fillets were measured and analyzed every 7 d.The results showed that the freezing temperature had a great effect on the color difference,driage and hardness of the fillets,and the lower the freezing temperature,the better the quality of the fillets.The freezing temperature had little effect on chewiness,elasticity and TVB-N while no significant effect on pH value.In conclusion,in the range of freezing temperature fluctuation of the existing processing technology,choosing lower freezing temperature and improving the freezing rate can delay the deterioration speed of frozen tilapia fillets.It is recommended that the freezing temperature be controlled at-40℃ and the freezing time within 40 min during processing to keep the quality of the fillets as much as possible.