Direct conversion of raw starch to lactic acid by Lactobacillus plantarum MTCC 1407 in semi-solid fermentation using sweet potato (Ipomoea batatas L.) flour

Lactobacillus plantarum MTCC 1407 was used for direct fermentation of raw starch in sweet potato (Ipomoea batatas L.) flour (SPF) to lactic acid (LA) under semi- solid fermentation using Mann Rogassa Sharpe medium containing (3%) SPF in lieu of glucose (2%) as carbon source. Response Surface Methodology (RSM) was used to evaluate effect of incubation period, temperature and pH on LA production, using a full factorial Central Composite Design (CCD). At optimum parameters (incubation period, 120 h; temperature, 35 degrees C and pH, 6.5), maximum starch conversion by Lb. plantarum MTCC 1407 to LA was 56.4%. The organism produced (L+) LA (23.86 g) from starch (55 g) present in SPF (100 g); LA production yield (mass LA produced mass starch present in SPF-1 x 100) was 43.4%.