Abstract

Whey containing 50 g.l ^-1 lactose was fermented to lactic acid in batch process byLactobacillus bulgaricus. The impact of 5 different media with change in volume percent of whey and nutrient was investigated at 32  ± 0.5°C. Substrate consumption and lactic acid production were determined at 0, 12, 24, 36, 48, 60 and 72 h. In these experiments, the volume percent of whey and nutrient was changed and highest lactic acid production (20.8 g/l) and rate of productivity (0.304 g/l.h) was achieved when the volume percent of whey was 80 (volume percent of nutrient diluted with water 20). The minimum rate of process was observed at the highest nutrient percent (50%), and at highest volume percent of whey in the medium (99%), inhibition occurred.

Key words: Lactic acid, whey, Lactobacillus bulgaricus, batch process, productivity.