Process scale-up of an efficient acid-catalyzed steam pretreatment of rice straw for xylitol production by C. Tropicalis MTCC 6192

Abstract

The present study focuses on operational parameters for the efficient acid catalyzed rice straw pretreatment process for xylitol production. 75.77 % xylose yield was attained when the 24 h presoaked rice straw (≤10 mm or ≤ 15 mm) in 1.5 % (v/v) H₂SO₄ was pretreated in the same reactor at 121 °C for 30 min. Neutralization with barium hydroxide produced insoluble salt and noticeably reduced HMF and furfurals. Xylitol yield of 0.6 g/g of xylose, was achieved by fermenting rice straw hydrolysate medium with C. tropicalis MTCC 6192. This two-step process of production of xylitol from xylose rich hydrolysate is much simpler and produced minimal inhibitors including organic acids such as acetic acid. This process is modified for upscaling at optimized parameters and will simultaneously minimize the pollution problem caused by rice straw and is also promising for commercial scale.

Keywords: Fermentation; Mass balance; Pretreatment; Rice straw; Xylitol; Xylose.