Simplified method for the measurement of total non-starch polysaccharides by gas-liquid chromatography of constituent sugars as alditol acetates

A procedure is described for the measurement and characterisation of total non-starch polysaccharides in plant foods by gas-liquid chromatography of individual sugars as alditol acetates. Starch, including that resistant to gelatinisation in boiling water, is dispersed with dimethyl sulphoxide and then hydrolysed with α-amylase and pullulanase. Starch-free material is hydrolysed with sulphuric acid and the released neutral sugars are measured as alditol acetates by using N-methylimidazole in order to catalyse the acetylation. Uronic acids are measured by a spectrophotometric method. The procedure is a modification of a more comprehensive method reported previously. It is relatively rapid and simple compared with gravimetric procedures, is applicable to a wide range of foodstuffs, can be carried out without special expertise in carbohydrate chemistry and is suitable for routine laboratory use.