The Impact of Food Processing on the Structure and Hypoglycemic Effect of Oat β-glucan

Abstract

The impact of food processing including baking, steaming and bread making, on the structure and hypoglycemic effect of oat β-glucan was studied. The structural analysis revealed the β-D-glucopyranosyl units of β-glucan was unchanged in aforementioned processing. The baking processing endowed β-glucan with increased molecular weight (Mw) and viscosity, which enhanced the capacity of β-glucan to delay starch digestion in vitro, such as the rapidly-digestible starch content decreased, the slowly-digestible and resistant starch content increased, and the glycemic index (GI) value decreased. Meanwhile, the inhibitory activity of β-glucan against α-glucosidase and α-amylase was enhanced by baking processing. By contrast, during steaming and bread making processing, β-glucan showed decreased Mw and viscosity, which accelerated starch digestion in vitro and reduced the inhibitory activity of β-glucan against α-glucosidase and α-amylase. Apart from that, baking processing promoted the physiological and antioxidant properties of β-glucan, but the properties decreased during steaming and bread making processing. The results suggest that oat raw materials can be treated with dry heat and high temperature, avoiding moist heat and fermentation treatments to maximize the hypoglycemic effect of β-glucan.

Keywords: Food processing; Functional properties; Hypoglycemic effect; Oat β-glucan.