Folate fortification of skim milk by a probiotic Lactococcus lactis CM28 and evaluation of its stability in fermented milk on cold storage

摘要

In order to enhance folate levels in fermented foods, a folate producing probiotic lactic acid bacterium isolated from cow’s milk and identified as Lactococcus lactis CM28 by 16S rRNA sequencing was used to fortify skim milk. Optimization of medium additives such as folate precursors, prebiotics and reducing agents along with suitable culture conditions enhanced folate levels in skim milk. Optimization resulted in a four fold increase in the extracellular folate (61.02 ± 1.3 μg/L) and after deconjugation the total folate detected was 129.53 ± 1.2 μg/L. The effect of refrigerated storage on the viability of L. lactis, pH, titratable acidity (TA) in terms of percentage lactic acid and finally on the stability of folate was determined. Only a slight variation in pH (4.74 ± 0.02 to 4.415 ± 0.007) and acidity (0.28 ± 0.028 to 0.48 ± 0.014 %) was noted during folate fermentation. During storage, only less than a log unit reduction was noted in the viable count of the probiotic after 15 days and about 90 % of the produced folate was retained in an active state.