Publication no. C-2002-0405-07R |  VIEW ARTICLE

Fermentability of Oat and Wheat Fractions Enriched in beta-Glucan Using Human Fecal Inoculation.

Peter J. Wood (1,2), Eva Arrigoni (3), S. Shea Miller (4), and Renato Amaḍ (3). (1) Agriculture and Agri-Food Canada, Food Research Program, 93 Stone Rd. West, Guelph, N1G 5C9, ON, Canada. (2) Corresponding author. Contribution S076 of Food Research Program and 11747 of Eastern Cereal and Oilseed Research Centre. (3) Swiss Federal Institute of Technology, Institute of Food Science, ETH Zentrum, CH-8092 Zurich, Switzerland. (4) Agriculture and Agri-Food Canada, Eastern Cereal and Oilseed Research Centre, Ottawa, K1A 0C6, ON, Canada. Cereal Chem. 79(3):445-454. Accepted December 20, 2001. 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., 2002.

Fermentation by human fecal bacteria of fractions of wheat bran prepared by preprocessing technology were examined and compared with a beta-glucan-rich oat bran and a purified beta-glucan (OG). The wheat fractions were essentially a beeswing bran (WBA), mainly insoluble dietary fiber, and an aleurone-rich fraction (WBB) containing more soluble fiber and some beta-glucan (2.7%). The oat bran (OB) had more endosperm and was very rich in beta-glucan (21.8%). Predigestion of WBB and OB to mimic the upper gastrointestinal (GI) tract gave digested wheat bran fraction B (WBBD) and digested oat bran (OBD), respectively. These predigested fractions were fermented in a batch technique using fresh human feces under anaerobic conditions. Changes in pH, total gas and hydrogen production, short chain fatty acids (SCFA), and both soluble and insoluble beta-glucan and other polysaccharide components, as determined from analysis of monosaccharide residues, were monitored. Fractions showed increasing fermentation in the order WBA < WBBD < OBD < OG. Variations in SCFA production indicated that microbial growth and metabolism were different for each substrate. Polysaccharide present in the supernatant of the digests had disappeared after 4 hr of fermentation. Fermentability of oat and wheat beta-glucan reflected solubility differences, and both sources of beta-glucan were completely fermented in 24 hr. Although the overall patterns of fermentation indicated the relative amounts of soluble and insoluble fiber, the anatomical origin of the tissues played a major role, presumably related to the degree of lignification and other association with noncarbohydrate components.