Glycemic response and glycemic index of semolina spaghetti enriched with barley β-glucan

Objective: The postprandial glycemic response and glycemic index (GI) of spaghetti made with semolina and the addition of two β-glucan barley concentrates, Glucagel (GG) and Barley Balance (BB), was studied. Methods: For each type of β-glucan concentrate, six spaghetti samples containing increasing percentages (0%, 2%, 4%, 6%, 8%, and 10%) of β-glucan were made. Nine healthy subjects were recruited for measuring the glycemic response and GI. Subjects were served portions of the test foods (50 g of available carbohydrates) and a reference food (50 g of glucose) on separate occasions. Capillary blood glucose was measured up to 120 min after consuming the spaghetti. The total glycemic response was calculated geometrically as the incremental areas under the curve (IAUC) using the trapezoid rule. The GI was calculated geometrically by expressing the IAUC for the test food as a percentage of each subject's average IAUC for the glucose. Results: The IAUC for spaghetti with and without β-glucan was significantly less compared with glucose. The GG spaghetti had IAUC values similar to the spaghetti without β-glucan concentrate. The BB spaghetti showed IAUC values lower than that of the spaghetti without β-glucan. In particular, the spaghetti with 10% BB had an IAUC 52% lower (P ≤ 0.017) than the spaghetti with β-glucan. The GI values for spaghetti with GG were statistically similar to the control. The GI of BB spaghetti decreased with increasing BB concentrations. In particular, the GI of 10% BB spaghetti was 54% lower (P ≤0.02; GI = 29) than that of the control (GI = 64). Conclusion: The BB concentrate significantly decreases the IAUC and GI of spaghetti at a dose of 10%. GI at the same concentrations does not.