Enhancing isolation of p-coumaric and ferulic acids from sugarcane bagasse by sequential hydrolysis

Abstract

To improve the yield of p-coumaric acid (p-CA) and ferulic acid (FA), sequential alkaline and acid hydrolysis was applied to sugarcane bagasse. Gas chromatography-mass spectrometry was used to quantify p-CA and FA. The sequential hydrolysis isolated more p-CA and FA from sugarcane bagasse than did alkaline hydrolysis or acid hydrolysis alone. Ethyl acetate extracted more p-CA and FA than chloroform. Increased temperature improved the yield of p-CA and FA. The total yields of p-CA and FA from sugarcane bagasse were 4.38 and 0.79%, respectively. For p-CA, the ester and ether bonds accounted for 93.60% and 6.40% of the total linkages, respectively. For FA, the ester and ether bonds accounted for 51.90% and 48.10% of the total linkages, respectively. Cleavage of the bond between hydroxycinnamic acid (p-CA and FA) and lignin was also confirmed by 13C NMR through comparison with the spectra of milled wood lignin and alkaline-soluble lignin.