Integrated treatment of perennial ryegrass: Structural characterization of hemicelluloses and improvement of enzymatic hydrolysis of cellulose

An integrated treatment coupling ultrasonic and hydrothermal pretreatments with sequential alkali post extractions was performed to isolate and characterize hemicelluloses from perennial ryegrass and improve the enzymatic hydrolysis efficiency of cellulose. The yield, chemical composition, and structure of water-soluble and alkali-soluble hemicelluloses obtained from the hydrothermal supernatant and hydrothermally pretreated ryegrass as well as the enzymatic hydrolysis efficiency of cellulose were comprehensively investigated by gel permeation chromatograph, high-performance anion exchange chromatography, Fourier transform infrared spectroscopy, and nuclear magnetic resonance spectra. Results showed that more than 90 % of the original hemicelluloses in ryegrass were released during the integrated treatment and all hemicellulosic fractions obtained were mainly composed of L-arabino-(4-O-methyl-D-glucurono)-D-xylans, galactoanrabinoxylans and beta-glucans. In addition, the effective removal of amorphous hemicelluloses and lignin significantly increased the cellulose enzymatic hydrolysis rate of ryegrass from 43.8 to 91.1 %. These results provided new insights into the collaborative utilization of hemicelluloses and cellulose in ryegrass.

Automated summary

By integrating ultrasonic and hydrothermal pretreatments with sequential alkali post extractions, hemicelluloses were successfully isolated and characterized from perennial ryegrass, leading to an improvement in the enzymatic hydrolysis efficiency of cellulose. The collaborative utilization of hemicelluloses and cellulose in ryegrass resulted in the effective removal of amorphous hemicelluloses and lignin, significantly increasing the cellulose enzymatic hydrolysis rate from 43.8 to 91.1%.