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

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.