Partial Acid Hydrolysis of Corn Fiber for the Production of L-Arabinose

Abstract

Conditions of acid hydrolysis for the preferential liberation of L-arabinose from corn fiber, a co-product of corn wet-milling processes, were investigated for the purpose of studying the production of L-arabinose. Prior to hydrolysis, starch was removed from the fiber by treatment with a-amylase. L-Arabinose was liberated rapidly at the beginning of hydrolysis and then slowed when the yield reached 12-13%. Conversely, the liberation of D-xylose was slow but linearly increased to more than 20% yield. Approximately 50 to 60% of L-arabinose in the destarched corn fiber (DSCF) was preferentially released with 0.2 N oxalic acid or 0.1 N sulfuric acid at 100° for 3 h. The ratio of Larabinose to D-xylose released was characteristic by the kind of acid used. Oxalic acid was the best for the production of L-arabinose, and hydrochloric acid was good for the production of D-xylose. Oligosaccharides were also produced in these hydrolyses. The amounts and degree of polymerization (DP) of the oligosaccharides yielded with 0.1 and 0.4 N oxalic acid at 100° for 1 h were 43%, DP 15.8, and 38%, DP 7.9, respectively. The suitable conditions so far examined for the preferential liberation of L-arabinose were hydrolysis with 0.3-1.0 N oxalic acid at 100° for 1 h, which produced 15% (62% of all L-arabinose in DSCF) L-arabinose. The yields of L-arabinose, D-xylose and soluble oligosaccharides could be controlled by the conditions of hydrolysis.