Influence Of Probiotic L. Casei Zhang On Texture, Aroma Generation And Sensory Characteristics Of Fermented Milk

Effect of Probiotic L.casei Zhang on sensory characteristics of yogurt was studied, and L. casei Zhang was inoculated with 21 Streptococcus.thermophilus strains(S.thermophilus)for fermented milk preparation, both at level of 1×107cfu/g. 21 S. thermophilus strains were isolated from traditional fermented milk products in the west of china and was inoculated at level of 2×107cfu/g as control. The sensory characteristics of fermented milk were determined after storage at 4℃for 1d. With the identical experimental condition, S. thermophilusB3 and S. thermophilus D2 were selected for the future research. The pH value, the viable counts of S. thermophilus and L. casei Zhang, viscosity, syneresis, texture profile, volatile compounds and sensory characteristics of fermented milk were determined during the refrigerated storage of 1d, 7 d, 14 d, 21 d and 28 d. The results showed that:1. S. thermophilus strains isolated from the same type of traditional fermented milk products exhibited different sensory characteristics.2. The products fermented with L. casei Zhang exhibited high viable count (>108cfu/g) after 28 days of refrigerated storage. The results suggested that L. casei Zhang showed good potential for application in functional foods and health-related products.3. The products fermented with L. casei Zhang and S. thermophilus strains exhibited higher content of the volatile composition .4. The products fermented with L. casei Zhang and S. thermophilus strains exhibited higher, hardness, fracturability, gumminess and chewiness.5. The products fermented with L. casei Zhang and S. thermophilus strains exhibited higher sensory scores.6. The fermented milk exhibited higher sensory quality during the refrigerated storage of 7 ~14 d.7. There were correlation between volatile composition and the sensory quality of odor,physical characterisation and the sensory quality of appearance.