Effect of Hulless Barley Flours on Dough Rheological Properties, Baking Quality, and Starch Digestibility of Wheat Bread

Hulless barley (Hordeum vulgare L.), also known as highland barley, contains nutritional compounds, such as beta-glucan and polyphenol, which can be added to wheat flour to improve the dough nutritional quality. In this study, different formulated dough samples were obtained by individually adding four hulless barley flours into flour of a wheat variety (Jimai 44, designated as JM) which has very strong gluten. The effects of hulless barley supplementation on gluten structure, dough rheological properties, bread-making properties, and starch digestibility were assessed. The results showed that compared with JM dough, substitution of hulless barley flour to wheat flour at levels ranging from 10 to 40% negatively affected gluten micro-structure and dough mixing behavior, because the cross-links of gluten network were partially broken and the dough development time and stability time were shortened. For the hulless barley-supplemented bread, specific volume was significantly (P < 0.05) increased while springiness was not greatly changed. Furthermore, the hydrolysed starch rate in hulless barley-supplemented bread was decreased, compared with that in JM bread. Importantly, the contents of beta-glucan, polyphenols and flavonoids in hulless barley-supplemented bread were 132.61-160.87%, 5.71-48.57%, and 25-293.75% higher than those in JM bread, respectively. Taken together, the hulless barley-supplemented bread has been fortified with enhanced nutritional components, more desirable bread-making quality, and improved starch hydrolytic properties, which shows a great potential to use hulless barley as a health supplement.