The Effect Of Milk Based And Culture Composition On L. Casei Zhang And B. Animalis V9 Fermentation Characteristics

In the present work, on the basis of L. casei Zhang and B. animalis V9, the effect of milk based and culture composition on pH value, titratable acidity (TA), viscosity, syneresis , free amino nitrogen (FAN) and microbiological stability of fermented milks was studied. The results showed that:1. The fermentation characteristics of L. casei Zhang and B. animalis V9 in milk were investigated. The acidity of milk combinely by L. casei Zhang and B. animalis V9 was faster than individually, which could effectively shorten the fermentation time. The fermentation time could be decreased when the solid content increased. The viable counts of L. casei Zhang after fermentation in the group with 12% solid content was significantly higher than that of other groups. During the storage, the survival rate of L. casei Zhang and B. animalis V9 in the group with 3:1 proportion were significantly higher than those of other groups. The viable counts of L. casei Zhang and B. animalis V9 in the group with 16% solid content was significantly higher than that of other groups. The inoculative proportion of these two bacteria and the solid content in raw milk play very important roles in the growth and survive ability of L. casei Zhang and B. animalis V9.2. The growth and survival activities of L. casei Zhang and B. animalis V9 in soymilk were investigated. The acidity of soymilk fermented combinely by L. casei Zhang and B. animalis V9 was faster than individually, which could effectively shorten the fermentation time. During storage, the biggest FAN content and the smallest pH and TA changes were observed in soymilk fermented with B. animalis V9 individually, while the pH values decreased and TA increased significantly in soymilk drink fermented with L. casei Zhang, respectively. L. casei Zhang and B. animalis V9 had excellent storage stability.3. The fermentation characteristics of L. casei Zhang in mare milk during refrigerated storage for 28 days were evaluated. It took more than 24 h for the mare milk samples to reach a pH of around 4.5 except at the highest inoculation rate of L. casei Zhang. There were no dramatic changes in the viable of L. casei Zhang in the fermented mare milk samples during storage at various inoculation levels. L. casei Zhang maintained high viability (above 108cfu/g) during storage.4. The effect of L. casei Zhang on fermentation characteristics of yogurt was studied. The yogurt inoculated with 2×10~6 cfu/g of L. casei Zhang had the highest apparent viscosity among the samples. The yogurt inoculated with 2×10~8 cfu/g of L. casei Zhang had lower pH values, apparent viscosities, and syneresis. The yogurt inoculated with 2×10~9 cfu/g of L. casei Zhang had the lowest value, syneresis and L. delbrueckii subsp. bulgaricus counts.