Application of bipolar electrodialysis on recovery of free lactic acid after simultaneous saccharification and fermentation of cassava starch.

The efficiency of bipolar electrodialysis (BED) for the recovery of lactic acid from fermentation broth was evaluated. Three systems of BED (bipolar-anion, bipolar-cation and bipolar-anion-cation) at fixed voltage (20 V) were compared using a model solution of ammonium lactate (100 g l(-1)). Results showed that bipolar-anion (BED-anion) was the most beneficial in terms of lactate flux, current efficiency, energy consumption and recovery ratio. Consequently, BED-anion was used to purify lactic acid from fermentation broth which had been pre-treated with mono-polar electrodialysis (MED). The final lactic acid concentration and lactate flux obtained were 144 g l(-1) and 393 g m(-2) h(-1), respectively. Using the two-step process (MED and BED-anion) the concentration of fermentation broth was increased by 33% and the total energy consumption was 2.76 kW h kg(-1).

Lactic acid production from sugar-cane juice by a newly isolated Lactobacillus sp.

A newly isolated sucrose-tolerant, lactic acid bacterium, Lactobacillus sp. strain FCP2, was grown on sugar-cane juice (125 g sucrose l(-1), 8 g glucose l(-1) and 6 g fructose l(-1)) for 5 days and produced 104 g lactic acid l(-1) with 90% yield. A higher yield (96%) and productivity (2.8 g l(-1 )h(-1)) were obtained when strain FCP2 was cultured on 3% w/v (25 g sucrose l(-1), 2 g glucose l(-1) and 1 g fructose l(-1)) sugar-cane juice for 10 h. Various cheap nitrogen sources such as silk worm larvae, beer yeast autolysate and shrimp wastes were also used as a substitute to yeast extract.