Effect of Oxidoreduction Potential on Lactic Acid Production by Lactobacillus paracasei

Abstract:

The aim of this research was to investigate the impact of extracellular oxidoreduction potential(ORP) on lactic acid production in batch culture by Lactobacillus paracasei.The ORP control was conducted by regulating the ratio of air flow rate to nitrogen flow rate in the inlet aeration of fermentor.As the results shown,the high ORP levels(the inlet air 1.5 L/min,-100mV,-150mV) resulted in higher lactic acid production but lower sugar-lactic acid conversion ratio,and the biomass was more than two times than that in the low ORP conditions(-200 mV,-300 mV,the inlet nitrogen 1.5 L/min).The highest lactic acid production(153 g/L) was obtained at the ORP level of-100 mV.The highest lactic acid yield(100.3%) was obtained at ORP level of-200 mV.Further more,the impact of ORP on the intracellular redox potential(NAD+/NADH) was investigated.