English abstract
Researches on bread making from combined barley and wheat flours are limited. Therefore, the main objective of this research was to study the effects of different proportions of barley and wheat flours on the physico-chemical properties and structure of bread. The bread was produced by mixing hard wheat flour (Canadian western Red Spring) with barley flour using different percentage of wheat and barley flour i.e., (100:0), (90:10), (85: 15) and (75: 25), respectively. The flour samples of wheat and barley were obtained using Buhler laboratory mill. The chemical compositions of the four formulated mixes were measured. The results showed variation in chemicals composition due to addition of barley, overall reduction in protein and gluten content and increasing in ash content and enzyme activity by adding of barley flour. The rheological characteristics of the four formulated dough mixes were studied by: Frarinograph, Extinsograph and Alveuograph, which showed significant decreasing of water absorption (p<0.05) and stability (p<0.01) by increasing barley flour, while no changes in extensibility and maximum heights. The structural and physical properties and visualized image analysis of breads were studied. Results showed; significantly decreasing (p<0.1) in crumb, apparent density with the increase of barley flour. Also, the porosity (i.e., fraction to total volume) increased with the increase of barley (p<0.1). There is no significant effect of barley (i.e. up to 25% of barley) on the final bread volume (p<0.05). Overall shape and pore structure at 10 % level of barley were similar to the pure wheat flour bread, while 15% and 25 % of barley showed more non-uniform and larger pores.
