BATCH AND CONTINUOUS PRODUCTION OF LACTIC-ACID FROM BEET MOLASSES BY LACTOBACILLUS-DELBRUECKII IFO-3202

Process variables were optimized for the production of lactic acid fro m pretreated beet molasses by Lacrobacillus delbrueckii IFO 3202 for b atch and continuous fermentations. In the batch fermentation, maximum yields (95. 4% conversion, 77.1% effective) and maximum lactic acid vo lumetric productivity (483 g dm(-3) h(-1)) was achieved at 45 degrees C, pH 6.0, 78.2 g dm(-3) sugar concentration with 10 g dm(-3) yeast ex tract. Various cheaper nitrogen sources were replaced with yeast extra ct on equal nitrogen bases in batch fermentation. Of all the nitrogen sources tested, yeast extract yielded the highest and malt sprouts yie lded the second highest level of lactic acid. In the continuous fermen tation, maximum lactic acid (4.15%) was obtained at a dilution rate of 0.1 h(-1). Maximum volumetric lactic acid productivity (11.20 g dm(-3 ) h(-1)) occurred at D = 0.5 h(-1) dilution rate.