Effects of β-glucan and various thermal processing methods on the in vitro digestion of hulless barley starch

Abstract

This study explored the effects of β-glucan and various processing methods on the digestion of hulless barley starch in vitro. The whole hulless barley showed significantly lower starch digestibility compared to that hydrolyzed by β-glucanase, indicating that β-glucan had inhibitory effects on starch digestion. However, β-glucan slightly accelerated the hydrolysis of extracted starch. Microscope observations of grains and flours revealed that the inhibitory effects of β-glucan benefited from the integral cellular structure of hulless barley. Besides, the hulless barley processed through flaking-roasting and stir-frying exhibited significantly lower starch digestibility (41.5% and 38.9%, respectively) and considerable intact cells and starch granules. The hulless barley processed by steam flash-explosion showed moderate starch digestibility (48.2%), which may be attributed to the encapsulation of starch-protein-β-glucan complexes. This elucidated the possible mechanism of β-glucan limiting the hydrolysis of hulless barley starch and provided useful direction to produce hulless barley products with desirable starch digestibility.