冷却牛肉贮藏过程中的品质变化

分析冷却牛肉贮藏过程中各品质指标的变化,确定理化指标和微生物指标的相关性,为提高牛肉的品质提供依据。文中测定了4℃贮藏的冷却牛肉在0、2、4、6、8、10、12、14 d的菌落总数、嗜冷菌总数、pH值、挥发性盐基氮、失水率、色差值,确定了各指标随保存时间的变化规律及其相关性。结果表明:在贮藏过程中,pH值呈现先下降后上升的趋势;挥发性盐基氮呈上升趋势;系水力逐渐下降;肉色a值、DE(d ifference error)值不断降低。在品质变化的各指标中,微生物菌落总数、嗜冷菌总数与pH值呈正相关,且差异显著(P<0.05);菌落总数与系水力、a值呈负相关性,差异显著(P<0.05)。其中菌落总数与挥发性盐基氮、a值的相关性较大且极显著相关(P<0.01)。由此可知,微生物的活动能引起牛肉理化指标的变化,通过测定挥发性盐基氮和a值可以客观反映冷却牛肉的微生物污染状况。

Study on Changes of Chilled Beef Quality During Storage

In order to provide the basis for improving the quality of beef,the changes of quality indexes on chilled beef during storage were analyzed and the correlations between physicochemical properties and microbial indexes were investigated.The changes of quality indexes including total plate count(TPC),psychrophilic count,pH values,total volatile basic nitrogen(TVB-N),water holding capacity,muscle color and the correlations of chilled beef during 4℃ were studied.The experiments were carried out at 0,2,4,6,8,10,12 and 14 days of storage.The results showed that during storage,the pH was first declined and then raised,TVBN increased,the water holding capacity and the redness a* value and DE(difference error) values of beef were gradually declined with the preservation time.There was a positive correlation between the logarithm of total number of microorganisms and psychrophilic count and the pH value with a significant difference(P<0.05),while the logarithm of total number of micro-organisms was negative correlated with the redness of chromatic aberration and the water holding capacity(P<0.05).TVBN and redness a* value showed the best correlation with TPC.Therefore,microorganism's activities can affect the changes of physicochemical index.TVBN and redness a* value could potentially be used as indicators in predicting the microbial quality of chilled beef objectively.