Publication no. C-2004-0324-03R |  VIEW ARTICLE

Molecular Weight Distribution of beta-Glucan in Oat-Based Foods.

Per Åman (1,2), Lena Rimsten (1), and Roger Andersson (1). (1) Department of Food Science, Swedish University of Agricultural Sciences, PO Box 7051, SE 750 07 Uppsala, Sweden. (2) Corresponding author. E-mail: <per.aman@lmv.slu.se> Cereal Chem. 81(3):356-360. Accepted October 3, 2003. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. American Association of Cereal Chemists, Inc., 2004.

Oats, different oat fractions as well as experimental and commercial oat-based foods, were extracted with hot water containing thermostable alpha-amylase. Average molecular weight and molecular weight distributions of beta-glucan in extracts were analyzed with a calibrated high-performance size-exclusion chromatography system with Calcofluor detection, specific for the beta-glucan. Oats, rolled oats, oat bran, and oat bran concentrates all had high Calcofluor average molecular weights (206 × 10(^4) to 230 × 10(^4) g/mol) and essentially monomodal distributions. Of the oat-containing experimental foods, extruded flakes, macaroni, and muffins all had high average molecular weights. Pasteurized apple juice, fresh pasta, and teacake, on the other hand, contained degraded beta-glucan. Calcofluor average molecular weights varied from 24 × 10(^4) to 167 × 10(^4) g/mol in different types of oat bran-based breads baked with almost the same ingredients. Large particle size of the bran and short fermentation time limited the beta-glucan degradation during baking. The polymodal distributions of beta-glucan in these breads indicated that this degradation was enzymatic in nature. Commercial oat foods also showed large variation in Calcofluor average molecular weight (from 19 × 10(^4) g/mol for pancake batter to 201 × 10(^4) g/mol for porridge). Boiling porridge or frying pancakes did not result in any beta-glucan degradation. These large differences in molecular weight distribution for beta-glucan in different oat products are very likely to be of nutritional importance.