Isolation of structurally distinct lignin-carbohydrate fractions from maize stem by sequential alkaline extractions and endoglucanase treatment

► Maize stem was treated with alkali before and after endoglucanase hydrolysis. ► Two soluble lignin-carbohydrate (LC) fractions were quantitatively recovered. ► LC1 and LC2 contained 39% and 8% of total lignin and 24% and 2.1% of ferulic acid. ► Thioacidolysis, acid/alkaline hydrolysis, FTIR were used to study each fraction. ► The procedure revealed important heterogeneity regarding structure of grass lignins.