Evaluation and Improvement of Antioxidant Activity of Water-soluble Lignin Products from Steam Explosion Processing of Corn Stalk

摘要

In this study,corn stalk was pretreated by steam explosion under various processing conditions,and the antioxidant activity of hydrolysates in the post-process washing liquor was analyzed using the 1,1'-diphenyl-2-picrylhydrazyl(DPPH•)scavenging method.The yield and composition of the hydrolysates obtained under different treatment conditions were also determined;the results indicated that the steam explosion extent had a significant effect on both properties.Under optimized conditions(1.5 MPa,20 min),the obtained hydrolysate had the highest phenolic compound yield(18.6 mg/g untreated corn stalk)and the highest radical scavenging capacity(IC_(50)=0.24 mg/mL).To confirm the positive effect of phenolic compounds on the antioxidant activity of the hydrolysate,one-step ethanol fractionation was carried out.Due to the enrichment of phenolic compounds,the ethanolsoluble fraction(ESF)exhibited significantly enhanced antioxidant activity with an IC_(50) value of 0.06 mg/mL,which was close to that of butylated hydroxytoluene(BHT,IC_(50)=0.056 mg/mL).Consequently,this work indicated that phenolic compounds have a significant effect on the antioxidant activity of hydrolysate from steam-exploded corn stalk and that simple one-step ethanol fractionation is an effective way to enrich the phenolic compounds in the hydrolysate and improve the antioxidant activity.