Interaction between barley β-glucan and corn starch and its effects on the in vitro digestion of starch.

A β-glucan was extracted from hull-less barley (HBBG) and its effects on the solution properties and in vitro digestion of corn starch (CS) were studied. Rheological results showed that HBBG diminished the gelling ability and increased the apparent viscosity of CS solution. The critical concentration was lowered from 1.10% (CS) to 0.48% (CS/HBBG mixture), and the slow relaxation component T22 decreased from 1417.47 to 464.16 ms after the incorporation of HBBG to CS solution. In vitro digestion study indicated that HBBG significantly increased the apparent viscosity of digesta and inhibited the starch hydrolysis and glucose diffusion. The entanglement and overlap formed by HBBG and CS interaction and aggregates of HBBG itself were considered to enhance the viscosity, thus limiting the water mobility of the system, reducing the contact of digestive enzyme with starch and diffusion of glucose to the small intestinal microvilli. This study suggests that HBBG can be recognized as an important ingredient in starch food to reduce postprandial glycemic responses.