Improvement in caffeic acid and ferulic acid extraction by oscillation-assisted mild hydrothermal pretreatment from sorghum straws

Abstract

This work investigated the effect of oscillation-assisted hydrothermal process on extraction of caffeic acid and ferulic acid from sorghum straws. The results showed that the oscillation-assisted hydrothermal process efficiently improved extraction of caffeic acid and ferulic acid. The oscillation-assisted hydrothermal process resulted in the extraction rates of 1275.48 and 1822.64 mg/L.h for caffeic acid and ferulic acid, respectively. Moreover, the oscillation-assisted hydrothermal process exerted destructive effects on hemicellulose, lignin and the amorphous regions of cellulose, contributing to the release of caffeic acid and ferulic acid in pretreated sorghum straws. The scavenging activities for hydroxyl, 1,1-diphenyl-2-picrylhydrazyl and 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulfonic acid radicals of the caffeic acid and ferulic acid extracts obtained by the oscillation-assisted hydrothermal process were determined to be 83.69 %, 84.17 % and 88.45 %, respectively.

Keywords: Caffeic acid; Ferulic acid; Oscillation-assisted hydrothermal process; Scavenging activities for free radicals; Sorghum straws.