Abstract
Milled wood lignins (MWL), which are considered to be in many aspects almost identical with lignins in situ, were isolated from Italian ryegrass (Lolium multiflorum LAM.) and alfalfa (Medicago sativa L.) stems and their chemical and physical properties were compared. The results of alkaline nitrobenzene oxidation, the IR and ^<13>C-NMR spectra and the methoxyl content of the MWLs indicated that Italian ryegrass and alfalfa lignins consist of guaiacyl-, syringyl- and p-hydroxyphenylpropane units and there is no considerable difference between the two lignins in the composition of these structural units. The number-average and weight-average molecular weights of the MWL determined by gel permeation chromatography were lower in Italian ryegrass than in alfalfa. Chemical and physical characteristics of forage grass and legume lignins were discussed in relation to their solubilization by hydrolytic treatments.
