Comparative Studies on Folate Production and Parameter Optimization in Fermented Milk from Yoghurt Starter Culture

Among the several causes reported for neural tube defects in newborns and cardiovascular diseases, deficiency of folate is one of the important reasons to be considered. Folate, water soluble vitamin, plays significant role in metabolic reactions. Humans cannot synthesize folate itself hence supplements and natural food sources are advisable to consume. Supplements have severe side effects on long term usage. Although milk is a poor soucrce of folate however folate producing microorganisms can enhance the folate content in the fermented milk. In this study, yogurt starter culture Streptococcus thermophilus NCIM No. 2904 and Lactobacillus helveticus NCIM No. 2733 were selected. Both the cultures were grown in MRS media and production was checked in reconstituted nonfat dry milk medium. Folate production was analysed by the TLC method and the modified ninhydrin assay which is not previously used on food products. Both cultures produced the folate in the fermented milk however S. thermophilus was found to be the best producer. After the production, optimization of culture condition such as temperature, pH, age of inoculum, inoculum volume and carbon source i.e. lactose concentration was carried out to obtain the enhanced folate content. S. thermophilus and L. helveticus gave the maximum production at 40°C and 37°C respectively and optimum pH was found to be 6.5 for both the cultures. Optimum age of inoculum was observed as the 15 hr while 5% inoculum volume was found to be optimum. Lactose concentration i.e. carbon source was also optimized and 2% lactose was found to be the optimum for the maximum folate production.