The incubation period of 48 h has been generally used for lactic acid production using different lactobacilli cultures (Chiarni et al., 1992; Gandhi et al., 2000; Kumar et al., 2001). Thus, reduction in the fermentation period along with high lactose conversion to L(+) lactic acid are the advantages of the developed process.
From the observations made during the process optimization studies, it could be concluded that maximum lactose conversion to lactic acid was obtained with the process conditions of pH 6.5, temperature 37°C and inoculum size 2% (v/v) of 20 h old culture under stationary conditions with an incubation of 36 h. The different optimal conditions reported by various workers for maximum lactic acid production could be explained by the differences in the nature of the strains and medium composition used in their studies. The above optimized process parameters can be used in scale up studies in further investigations.
ACKNOWLEDGEMENTS
Dr. Parmjit S. Panesar acknowledges support from the Department of Science and Technology (DST), Government of India, New Delhi, for the award of a BOYSCAST fellowship. The authors are grateful to Visualisation and Imaging Network (VIN), UK, and National Bank for Industrial Micro-organisms and Cell Cultures, Bulgaria for providing L. casei strain.