Determination of beta-Glucan Molecular Weight Using SEC with Calcofluor Detection in Cereal Extracts

A high-performance size-exclusion chromatography system (HPSEC) was set up with detection based on the specific binding of Calcofluor to betaglucan for determination of amount and molecular weight of beta-glucan in different cereal extracts. To calibrate the HPSEC system, a purified betaglucan was fractionated into narrow molecular weight ranges and the average molecular weight was determined before analysis on the HPSEC system. The detector response was similar for beta-glucans from oats and barley and appeared to be independent of molecular weight. Four different methods for extraction of beta-glucan from different cereal products were tested: two alkaline, one with hot water and added alpha-amylase, and one with water and added xylanase. Inactivation of endogenous beta-glucanase was crucial for the stability of the extracts, even when extracting at high temperature or pH. Yields varied widely between the different extraction methods but average molecular weight and molecular weight distribution were similar. Extraction with sodium hydroxide generally gave a higher yield and molecular weight of beta-glucan in the extracts.