Consecutive Recovery of Non-Structural Sugars and Xylooligomers from Corn Stover using Hot Water and Acidified Calcium Chloride

Abstract

Corn stover, which has a high non-structural sugar content, was treated by two-stage fractionation using water and acidified CaCl2 for the consecutive recovery of non-structural sugars and xylooligomers. In this process, water treatment under mild conditions (60 degrees C to 140 degrees C) was used for the recovery of non-structural sugars in the first stage, followed by the recovery of xylooligomers using acidified CaCl2 in the second stage under severe conditions (160 degrees C to 180 degrees C). For the recovery of non-structural sugars, a water treatment at 80 degrees C was observed to be effective, recovering 95.6% of the non-structural sugars. With a non-structural sugar-free solid, the reaction conditions for the second stage of treatment using acidified CaCl2 were statistically optimized. The highest recovery yield of xylooligomers (72.5%) was obtained under optimum conditions (172.9 degrees C, 22.2 min, 4.7% CaCl2). With the two-stage fractionation process, the glucan digestibility of treated solid was enhanced from 34.0% for untreated corn stover to 91.0% for the treated solid (with 15 FPU/g-glucan).