超声前处理对冷藏海鲈鱼品质及蛋白质特性的影响

Effects of ultrasound pretreatment on the quality and protein characteristics in Japanese sea bass(Lateolabrax japonicas)during refrigeration

为研究超声波处理时间对海鲈鱼冷藏期间品质及蛋白质特性变化影响,将新鲜鲈鱼片使用20 kHz,600 W的超声分别处理5 min(U1)、10 min(U2)与20 min(U3),未超声的无菌水处理样品为对照组(CK),4组样品沥干后装入无菌PE袋中,于4℃冰箱中贮藏。冷藏期间每隔2 d测定微生物指标(嗜冷菌数、菌落总数)、理化指标〔pH值、总挥发性盐基氮(total volatile base-nitrogen,TVB-N)、质构〕与蛋白质特性〔肌原纤维碎片化指数(myofibril fragmentation index,MFI)、Ca 2+-ATPase活性、总巯基含量〕,并结合蛋白质荧光强度与感官分析综合评价超声处理时间对海鲈鱼冷藏期间品质及蛋白质特性影响。结果表明,样品经超声处理后,其菌落总数、嗜冷菌数、pH值与TVB-N值的增长速度明显缓于对照组;其MFI值的增幅高于对照组,硬度值相应降低,可见超声处理使样品嫩度相应提高。然而,其Ca 2+-ATPase活性与总巯基含量与超声处理时间负相关,表明超声处理会破坏样品的蛋白结构。由荧光强度分析可知,与对照组相比,超声处理可延缓样品贮藏期间荧光强度的下降,尤其以U2处理效果最佳。综上所述,以超声处理10 min对样品的综合品质保持效果相对较好,与对照组相比,其可至少延长冷藏海鲈鱼货架期2 d。

In order to study the effects of ultrasound time on the quality and protein characteristics of Japanese sea bass(Lateolabrax japonicas)during refrigerated storage,fresh samples were treated with ultrasound at 20 kHz and 600 W for 5 min(U1),10 min(U2)and 20 min(U3)respectively,which treated with sterile water as the control group(CK).Then different groups were drained,put into PE bags and stored in a refrigerator at 4℃.Different parameters,such as microbial[psychrophilic bacteria counts(PBC),total viable counts(TVC)],physicochemical[pH,total volatile base nitrogen(TVB-N),texture profile analysis(TPA)],protein characteristics(myofibril fragmentation index(MFI),Ca 2+-ATPase activity,total sulfhydryl content),combined with protein fluorescence intensity and sensory evaluation,were used to evaluate the effects of different ultrasound time on the quality and protein characteristics of Lateolabrax japonicas during cold storage at two days interval.The results showed that the increase rate of TVC,PBC,pH and TVB-N value in ultrasound(US)samples were significantly slower than those of CK group;the increase rate of MFI value in US samples was higher than that of CK group,the hardness value in US groups was greatly reduced,which can be seen that the ultrasound treatment could make the tenderness of samples increase.However,the results of Ca 2+-ATPase activity and total sulfhydryl content were negatively correlated with ultrasound time,which indicated that ultrasound treatment could destroy the protein structure of samples.The increase of fluorescence intensity in US groups could be delayed by ultrasonic treatment during storage,especially for the U2 treatment.Above all,the quality of samples treated with ultrasound for 10 minutes is better,which can extend the shelf life of Lateolabrax japonicas during refrigerated storage for another two days.