Glycemic Response to Oat Bran Muffins Treated to Vary Molecular Weight of beta-Glucan.

Susan M. Tosh (1,2), Yolanda Brummer (1), Thomas M. S. Wolever (3), and Peter J. Wood (1).

(1) Guelph Food Research Centre, Agriculture and Agri-Food Canada, Guelph, ON. (2) Corresponding author. E-mail: <ToshS@agr.gc.ca> (3) Department of Nutrition, University of Toronto, Toronto, ON. Cereal Chem. 85(2):211-217. Accepted November 2, 2007. Copyright 2008 AACC International, Inc.

Abstract: Oat bran muffins, containing 4 or 8 g of beta-glucan per two-muffin serving, were prepared with or without beta-glucanase treatment to produce a range of beta-glucan molecular weights from 130,000 to just over 2 million. Following an overnight fast, the glycemic responses elicited by the untreated and treated muffins was measured in 10 healthy subjects and compared with a control whole wheat muffin. Taken all together, the 4-g beta-glucan/serving muffins reduced blood glucose peak rise (PBGR) by 15 ± 6% compared with the control. The 8-g beta-glucan/serving muffins had a significantly greater effect (44 ± 5% reduction compared with the control, P < 0.05). The efficacy of the muffins decreased as the molecular weight was reduced from a 45 ± 6% reduction in PBGR (P < 0.05) for the untreated muffins (averaged of both serving sizes) to 15 ± 6% (P < 0.05) for muffins with the lowest molecular weight. As the molecular weight was reduced from 2,200,000 to 400,000, the solubility of the beta-glucan increased from a mean of 44 to 57%, but as the molecular weight was further decreased to 120,000, solubility fell to 26%. There was a significant correlation (r(^2) = 0.729, P < 0.001) between the peak blood glucose and the product of the extractable beta-glucan content and the molecular weight of the beta-glucan extracted.