富硒乳酸菌发酵酸奶贮藏品质变化

Quality Changes of Yogurt Fermented by Selenium-enriched Lactic Acid Bacteria during Storage

为了研究富硒乳酸菌发酵酸奶贮藏期间的品质变化,对富硒乳酸菌发酵酸奶(富硒酸奶)与非富硒乳酸菌发酵酸奶(对照酸奶)的感官性状、理化指标以及两种酸奶4℃贮藏过程中的菌落总数、滴定酸度、黏度、保水性、色泽、抗氧化性和感官评分进行分析。结果表明,贮藏第1 d时与对照酸奶相比,富硒酸奶的pH较高,总固形物含量和硒含量较高(对照酸奶的14.3倍),颜色更偏红、偏黄。富硒酸奶的乳酸菌菌落总数在贮藏第7 d后高于对照酸奶(P>0.05),而整个贮藏过程中滴定酸度、黏度低于对照酸奶(P<0.05),持水性低于对照酸奶(P>0.05)。相同贮藏期内富硒酸奶的过氧化值低于对照酸奶(P>0.05),对DPPH自由基、ABTS+自由基的清除活性高于对照酸奶(P<0.05),二者的感官评分接近(P>0.05)。富硒乳酸菌发酵酸奶具有较高的抗氧化活性、较低的后酸化,更有利于贮藏过程中品质的保持。

In order to study quality changes of yogurt fermented by selenium-enriched lactic acid bacteria(Se-enriched yogurt)during storage,the sensory characteristics and the physicochemical indexes were analyzed and the total number of colonies,titrated acidity,viscosity,water-holding capacity,color,antioxidant activity and sensory evaluation values of Se-enriched yogurt during storage were evaluated,compared with non selenium-enriched lactic acid bacteria fermented yogurt(control yogurt).The results showed that during the storage of 1st d,the Se-enriched yogurt had higher pH,higher total solid content and selenium content(14.3 times of the control yogurt),and with more red and yellow color compared with the control yogurt.The total number of colonies of Se-enriched yogurt was significantly higher than that of control yogurt after 7 days of storage.However,during the whole storage process,the titrated acidity,viscosity and water holding capacity of Se-enriched yogurt were lower than those of the control yogurt.In the same storage period,the peroxide value of Se-enriched yogurt was lower than that of control yogurt,and the scavenging activities for DPPH free radical and ABTS+free radical were significantly higher than that of control yogurt.The sensory scores of Se-enriched yogurt was similar to control yogurt.Se-enriched yogurt was with higher antioxidant activity and lower post-acidification compared with control yogurt,which was more conducive to the maintenance of quality during storage.