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

TLDR

The method builds on a previously reported comprehensive protocol for polysaccharide analysis. The study presents a protocol to quantify and characterize total non‑starch polysaccharides in plant foods via GC of alditol acetates. The protocol separates starch by DMSO dispersion and enzymatic hydrolysis, hydrolyzes starch‑free material with sulfuric acid, quantifies neutral sugars as alditol acetates using N‑methylimidazole, and measures uronic acids spectrophotometrically. The method is rapid, simple, broadly applicable to diverse foods, requires no specialized carbohydrate chemistry expertise, and is fit for routine laboratory use.

Abstract

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.