Glycemic response to oat bran muffins treated to vary molecular weight of β-glucan

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 P-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 P-glucan content and the molecular weight of the beta-glucan extracted.