Platform Study on the Development of a Nondetoxified Rice Straw Hydrolysate to Its Application in Lipid Production from Mortierella alpina

Abstract

In the present work, a mild acid saccharification approach for rice (Oryza Sativa) straw was developed by Response Surface Optimization. A 23 central composite experimental design with variable factors as duration (minutes), mild acid concentration % (v/v) and minimum solid loading % (w/v) was chosen to optimize the hydrolysis process, fixing the operating temperature to a moderate minimum of 121°C. The study determined 5% solid loading, 0.75% acid concentration and 150 (min)-residence duration as optimum, for enhanced reducing sugar release. To compensate the reduced saccharification efficiency under mild operating conditions, a novel approach of multi-tier saccharification was implemented at optimal conditions of saccharification. HPLC analysis revealed the final reducing sugar yield of 0.76 g reducing sugar/gram straw (47.9g/l and 35g/l concentration in two consecutive saccharification cycles) and glucose, galactose, and xylose as major reducing sugars in hydrolysate. On assessing the hydrolysate as a ...