Cereal Chem 69:647-653   |  VIEW ARTICLE

Oat Bran Concentrates: Physical Properties of Beta-Glucan and Hypocholesterolemic Effects in Rats.

Y. Malkki, K. Autio, O. Hanninen, O. Myllymaki, K. Pelkonen, T. Suortti, and R. Torronen. Copyright 1992 by the American Association of Cereal Chemists, Inc. 

Viscosity, hydrodynamic properties, and molecular weight distribution of beta-glucan in oat bran and variously prepared fiber concentrates were investigated, and the results were correlated with the hypocholesterolemic effect in rats receiving bran or the concentrates as a dietary supplement. In neutral aqueous extracts of samples having similar total beta-glucan content, an ethanol-water, wet-milled concentrate gave higher viscosities than untreated oat bran or cold-water, wet-milled concentrate. However, beta-glucan isolated by hot alkaline extraction from untreated bran gave higher viscosity than beta-glucan preparations isolated from the concentrates. The viscosity and molecular weight of beta-glucan was reduced at acidic conditions under concentration and by trypsin. Beta-glucan from a cold-water, wet-milled concentrate had the highest molecular weight and also higher hydrodynamic volume than beta-glucan isolated from the other concentrates. In rats fed diets containing 3.3% beta-glucan from oat bran fiber concentrates but no added cholesterol or cholic aicd, the serum total cholesterol level was lowered by 30% with the ethanol-water, wet-milled concentrate and by 10% with the cold-water, wet-milled or hydrolyzed concentrate, relative to the initial cholesterol levels and to the levels of the control group receiving cellulose in the diet. The diet containing untreated oat bran was ineffective. Dependence of the hypocholesterolemic action on extractability, viscosity, hydrodynamic properties, and molecular weight of beta-glucan is discussed.