Screening of media components and process parameters for production of L(+) lactic acid from potato waste liquid using amylolytic Rhizopus oryzae

Abstract

The utilization of potato waste liquid instead of synthetic substrates for lactic acid production cannot only reduce the production cost but also makes the process environment effective. Unlike many lactic acid bacteria, lactic acid producing Rhizopus strains generates L(+) lactic acid as a sole isomer of lactic acid. Furthermore, some Rhizopus spp. are amylolytic in nature and can produce lactic acid from starchy substrates without prior saccharification. This study aimed at the utilization of potato waste liquid for the production of L(+) lactic acid using amylolytic Rhizopus oryzae MTCC 8784. The effect of media components and process parameters on simultaneous saccharification and fermentation of potato waste liquid by fungal strain has been studied to maximize the production of L(+) lactic acid. The results revealed that highest lactic acid production (15.5 g l–1) was obtained with potato waste liquid containing 30 g l–1 starch supplemented with soya okara hydrolysate (1.5%, v/v), calcium carbonate (1.5%, w/v), and salts. In terms of process parameters, the maximum L(+) lactic acid (18.15 g l–1) production was obtained at pH 6 with temperature 30 °C, agitation of 150 r.p.m., after incubation period of 48 h.