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

¹Swedish University of Agricultural Sciences, Department of Food Science, P.O. Box 7051, SE-750 07 Uppsala, Sweden. ²Corresponding author. lena.rimsten@lmv.slu.se.

A high-performance size-exclusion chromatography system (HPSEC) was set up with detection based on the specific binding of Calcofluor to β-glucan for determination of amount and molecular weight of β-glucan in different cereal extracts. To calibrate the HPSEC system, a purified β-glucan 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 β-glucans from oats and barley and appeared to be independent of molecular weight. Four different methods for extraction of β-glucan from different cereal products were tested: two alkaline, one with hot water and added α-amylase, and one with water and added xylanase. Inactivation of endogenous β-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 β-glucan in the extracts.