Fermentative lactic acid production from a renewable carbon source under response surface optimized conditions without alkali addition: a membrane-based green approach

Abstract

Experimental investigations were carried out on production of lactic acid from sugar cane juice by Lactobacillus delbruckii in a membrane-integrated and non-neutralizing fermentation system after an initial optimization study. As the process produced lactic acid directly instead of through lactate salt as in traditional processes, many intermediate steps could be bypassed. Most relevant operating parameters like temperature, concentrations of yeast extract, and peptone were optimized first through rigorous experimentation following response surface methodology. At 41°C, 116.28 g l⁻¹ lactic acid concentrations was reached with 13.82 g l⁻¹ yeast extract and 7.69 g l⁻¹ peptone concentration. However, higher yield (96%) was obtained with diluted sugarcane juice containing 102.20 g l⁻¹ sucrose. The most remarkable achievement of this new design is that it can produce lactic acid with high degree of purification directly from a renewable and cheap carbon source in an eco-friendly process representing high process intensification.