Bread volume and crumb grain study: Effects of wheat and flour characteristics and starch granule size.

摘要

Wheat and flour characteristics of 49 hard red winter wheats harvested in 1997 were measured, as well as their breadmaking quality. Those data were used to develop prediction equations for loaf volume (R2 = 0.920) and crumb grain score (R2 = 0.734). Using only six wheat parameters gave a loaf volume prediction with R2 = 0.860 which could be beneficial for wheat breeders and market system.; Particle size distributions showed that flours with finer granulation produced breads with better crumb grain score. Breadmaking quality of flours fractionated by sieving was influenced more by differences in protein content rather than flour particle size. Reducing flour particle size by further pin-milling improved loaf volume up to 5%, but the results of crumb grain score were inconsistent. Gas cells in bread crumb became elongated with particle size reduction. Crumb grain score was correlated positively with flour protein content and some protein subclasses, but was more highly correlated with rheological mixing properties of dough. Most protein subclasses were correlated positively with loaf volume but negatively with mixograph mix time. On the other hand, insoluble (50% aqueous 1-propanol) polymeric protein showed a positive correlation with the mix time.; Baking results with reconstituted flours with varying proportions of large and small wheat starch granules showed that there is an optimum weight ratio of ∼30% small to 70% large granules for crumb grain score, gas cell elongation ratio, and crumb fineness. Correlation coefficients by regression analysis indicate that crumb characteristics are influenced not only by starch granule size but also by other properties like swelling power and specific surface area. Apparently, the proper distribution of water in the dough components including liquid film, starch, and gluten seem important for stable gas cell development during early baking stage. Bread firmness decreased with an increased level of small starch granules in flour probably because the small granules contain a somewhat reduced level of amylose and/or an increased level of lipids.