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

Abstract

Hulless barley (Hordeum vulgare L.), also known as highland barley, contains nutritional compounds, such as β-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 β-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.

Effects of Quinoa Flour on Wheat Dough Quality, Baking Quality, and in vitro Starch Digestibility of the Crispy Biscuits

“…As shown in Table 1 , apparent amylose content of quinoa flour is lower than that of wheat flour, which can be explained that quinoa flour is composed of small granules. Given that more B-type granules can improve the dough rheological properties ( 9 , 17 ), the reconstituted flours are expected to show better rheological behavior.…”

“…UPP% is often used as an index to evaluate the wheat quality ( 6 , 9 ), and in this study it is introduced to evaluate the quinoa quality. Consequently, the UPP% of quinoa-wheat flours was explored and its effect on the dough strength investigated.…”

“…The protein area and protein junctions of Q10 increased slightly, without significant difference, compared to those of Q0. Lacunarity reflects the regularity of voids in the network structure and a higher value indicates weaker dough strength ( 9 , 47 ). With the addition of quinoa flour, lacunarity became larger, indicating the reconstituted doughs became weaker ( Supplementary Figure 1D ).…”

“…However, in this study, the rheological properties of the dough were improved. This may be attributed to that the starch of quinoa contains more small-sized granules, which combine more closely with gluten network ( 9 , 51 ). The improved effect of quinoa starch may offset the decreased effect of the diluted gluten.…”

“…Therefore, it is very promising to introduce this parameter into other non-wheat crops to analyze protein characteristics. UPP% has been used to analyze the protein quality characteristics of hulless barley-wheat reconstituted flour and UPP% of wheat-hulless barley system decreased with the increase of hulless barley proportion ( 9 ). The performance of gluten microstructure affects dough behaviors during the dough formation process ( 10 ), which can be characterized by the parameters i.e., protein area, protein junctions, and lacunarity used in protein network analysis ( 11 , 12 ).…”