冷藏处理方式对大目金枪鱼贮藏品质及内源酶活性的影响

为研究不同冷藏处理方式对大目金枪鱼贮藏品质与内源酶活性的影响,分别研究4℃冷藏、碎冰与流化冰贮藏的大目金枪鱼的理化指标(质构特性、电导率与总挥发性盐基氮)、微生物指标(菌落总数)、ATP关联产物与酶活(腺苷脱氨酶、酸性磷酸酶),并结合低场核磁共振技术共同表征不同冷藏条件对大目金枪鱼综合品质的影响。结果表明:随着贮藏时间的延长,流化冰处理可显著抑制大目金枪鱼肉电导率值、TVB-N值、菌落总数、次黄嘌呤(Hx)含量的升高,其质构值(硬度、弹性、咀嚼性)、三磷酸腺苷及肌苷酸含量降幅较其余两组缓慢。此外,流化冰处理金枪鱼样品的K值、H值、Ki值明显低于另外两组,Fr值呈为平缓地降低趋势。3组样品贮藏后期的酸性磷酸酶和腺苷脱氨酶活性显著增长,其中酸性磷酸酶活性与菌落总数显著相关,流化冰对其有一定抑制作用。通过低场核磁共振分析得出,大目金枪鱼鱼肉中的不可流动水(T22)逐渐向自由水(T23)转化,肌原纤维内水分含量降低,肌肉品质劣化。由此得出,与4℃冷藏组、碎冰处理组样品相比,流化冰处理可通过控制内源酶活性和微生物生长,减缓ATP关联产物的降解与品质劣变,从而达到延缓大目金枪鱼食用品质劣变的目的。

Effect of Refrigerated Treatment Methods on the Quality Change and Endogenous Enzyme Activity of Big-eye Tuna(Thunnus obesus)

To study the effect of different refrigerated treatment methods on the quality change and endogenous enzyme activity of big-eye tuna(Thunnus obesus). Samples were stored under different refrigerated conditions(refrigerated storage(CK), crushed ice(CI) and slurry ice(SI)), the physicochemical(texture profile analysis(TPA), electrical conductivity and total volatile base-Nitrogen(TVB-N)), microbiological(Total viable counts), ATP-related compounds and enzyme activities(Adenosine deaminase(ADA) and Acid phosphatase(ACP)) indexes were measured respectively.The water mobility was evaluated by Low-field nuclear magnetic resonance(LF-NMR). The results showed that when compared with other groups, samples in SI could control the increase of electrical conductivity, TVB-N value, TVC and Hx contents. The hardness, springiness, chewiness, ATP and IMP content also declined slowly. The values of K, H, Ki were lower than other groups and Fr value showed a more gentle downward trend. The activities of ACP and ADA showed a upward trend in the later of storage, which could be restrained by SI. The activity of ACP and TVC had a certain correlation. The decrease of T22 and the increase of T23 indicated that water content in myofibrils was lost and the quality of big-eye tuna was deteriorated. Therefore, SI storage could slow down the degradation of ATP and quality deterioration in big-eye tuna by controlling the activity of endogenous enzyme and microbial growth.