Potential use of Lactobacillus casei AST18 as a bioprotective culture in yogurt

This study investigated the inhibitory effects of Lactobacillus casei AST18 as a biocontrol agent on fungi spoilage in yogurt. In a yogurt preservation period experiment and mould-proof accelerated testing at 4 °C, the addition of 2% (v/v) L. casei AST18 in yogurt completely inhibited mould growth; mould growth was significantly delayed and spore germination was inhibited at 30 °C. The addition of L. casei AST18 improved the quantity of Lactobacillus, but the number of Streptococcus lactis in 2% AST18-added yogurt decreased by 1.0 Log (cfu/mL) compared with that in the blank group. L. casei AST18 exerted no significant influence on viscosity, water holding capacity, sensory quality, pH and titratable acidity. The post-acidification effect of L. casei AST18 was low. L. casei AST18 conspicuously inhibited the growth of filamentous fungi. Therefore, L. casei AST18 can be used as a bioprotective culture in yogurt to prevent fungal growth and extend shelf life.