Fractionation and characterization of chlorophyll and lignin from de-juiced Italian ryegrass (Lolium multifolrum) and timothy grass (Phleum pratense)

摘要

In this study, de-juiced Italian ryegrass and timothy grass were successfully fractionated into one chlorophyll rich fraction, two lignin fractions, two hemicellulosic preparations, and one cellulosic fraction by sequential processes with 80% ethanol containing 0.2% NaOH, 2.5% H_2O_2-0.2% EDTA containing 1.5% NaOH, and 2.5% H_2O_2-0.2% TAED containing 1.0% NaOH at 75℃ for 3 h, respectively. The yields of chlorophyll rich fraction and total lignin fraction were found to be 6.1 and 11.0% from de-juiced Italian ryegrass, and 12.7 and 13.2% from de-juiced timothy grass. It should be noted that the two chlorophyll rich fractions contained noticeable amounts of contaminated hemicelluloses (17.1-18.8%) and lignin, whereas the four lignin fractions contained only small amounts of bound hemicelluloses (5.6-8.6%). Nitrobenzene oxidation and NMR spectra of the lignin fraction revealed that the presence of both guaiacyl and syringyl units, as well as p-hydroxyphenyl structures. Small amounts of esterified p-coumaric acids and mainly etherified ferulic acids were also identified in the lignin fractions. It was found that the lignin fractions obtained from the two different grasses had very similar structural composition. They are distinguished by rather low amounts of β-O-4 structures, resinol units (β-β), and of condensed units β-5 and 5-5). This trait is even more pronounced in the production of phenolic compounds for chemical industry from grass.