Physicochemical, microbial, and sensory properties of yogurt supplemented with nanopowdered chitosan during storage

摘要

This study was carried out to determine the possibility of adding nanopowdered chitosan (NPC) into cholesterol-reduced yogurt to improve the functionality of yogurt and the effects of adding NPC on the physico-chemical, microbial, and sensory properties of the products during storage. The pH values and mean lactic acid bacteria counts of NPC-added (0.3 to ～0.7%, wt/ vol) and cholesterol-reduced yogurt ranged from 4.19 to 4.41 and from 4.75 × 10~8 to 9.70 × 10~8 cfu/mL, respectively, when stored at 4℃ for 20 d, thereby indicating a possibility of prolonging the shelf life of yogurt. In color, the a~* and b~* values for cholesterol-reduced yogurt were not significantly influenced by the addition of NPC (0.1 to ～0.7%, wt/vol); however, the L~* values significantly decreased with the addition of the greatest concentration (0.7%, wt/vol) of NPC at 0-d storage. The sensory test revealed that the astringency scores significantly increased at 0-d storage when the greatest concentration (0.7%, wt/vol) of NPC was added into cholesterol-reduced yogurt. Based on the data obtained from the current study, it is concluded that concentrations (0.3 to ～0.5%, vol/vol) of NPC could be used to produce an NPC-added and cholesterol-reduced yogurt without significantly adverse effects on the physico-chemical, microbial, and sensory properties.