IMPACT OF SACCHAROMYCES CEREVISIAE ON VIABILITY OF PROBIOTIC LACTOBACILLUS RHAMNOSUS IN FERMENTED MILK UNDER AMBIENT CONDITIONS

The viability of probiotic Lactobacillus rhamnosus HN001 was examined in fermented milk with and without Saccharomyces cerevisiae var. bayanus EC-1118. The yeast enhanced the viability of L. rhamnosus at 30C but not at 12C. High temperature (40C) was detrimental to yeast vitality and diminished its viability-enhancing effect. The yeast inoculated at 10(3) cfu/g multiplied to 10(6) cfu/g and enhanced the viability of L. rhamnosus. Viable yeast exerted maximum beneficial effects, although the cell-free yeast supernatant also enhanced the survival of L. rhamnosus. The addition of yeast after fermentation decreased its viability-enhancing effect. Removal of oxygen achieved the viability of L. rhamnosus that was comparable with that achieved in the presence of viable yeast. The results suggest that the improved viability of L. rhamnosus might involve yeast viability, oxygen removal and yeast metabolite(s). The findings would help develop novel microbial starter technology for ambient-stable fermented milks with live probiotics.