Extraction of arabinoxylan from corncob through modified alkaline method to improve xylooligosaccharides synthesis

Abstract

A modified alkaline protocol involving a combination of NaOH and NH4OH was employed for the isolation of hemicellulose from corncob. It was possible to obtain a hemicellulose fraction consisted of nominal branching constituents, such as arabinose, uronic acid and lignin. During the extraction of hemicellulose, alkaline reagents promoted selective cleavage of ester and ether linkages in corncob biomass depending on its nature and severity. Based on modeling analysis, reaction parameters, such as alkali concentration and temperature significantly influenced the amount of total hemicellulose extracted. Subsequent hydrolysis of isolated hemicellulose in the presence of H2SO4 resulted in better conversion (69 wt%) with enriched XOs conc. (73.68% with DP up to 4) than other fractions under milder conditions. Advantageously, gas phase NH3 formation was achieved during the reaction, where NaOH and NH4OH mix was used at an equal ratio that could significantly help in reducing the overall processing cost of XOs production (through recovery and reuse) during large-scale manufacture.