An improved methylation procedure for the analysis of complex polysaccharides including resistant starch and a critique of the factors which lead to undermethylation

Abstract Deficiencies in the widely used Hakomori method of methylation are described. Evidence is given that this method of linkage analysis often gives levels of undermethylation which hamper the detailed study of complex carbohydrates from plant cell walls. A modified method using sodium hydroxide as base is described which is capable of fully methylating polymers for which the Hakomori method generally fails and which does not promote the carbohydrate oxidation typical of a former procedure using this reagent. An explanation of its efficacy is advanced. Analyses of retrograded, α‐amylase‐resistant starches obtained by the modified method are reported.