Relationship between functionality and structure in barley starches

Abstract

Normal and waxy barley grains were divided into eight fractions (A–H) from the surface layer to the center with a machine used to polish brewers' rice, respectively. The large, medium and small granule starches were isolated from the fractions. The functionalities of starches were examined in this study. The relationship between the functionalities of starch and the parameters of structure was also analyzed. The degree of hydrolysis increased in the order of large, medium and small granules in the same fraction both waxy and normal barley, but decreased from the surface to the center of grain with granule size. The small granule starches showed the greatest swelling power both waxy and normal barley in the three granule sizes, but was the easiest to gelatinize and to retrograde. The gel from large granules was the most stable both waxy and normal barley in the three granule sizes. Also the gel for waxy barley grain is more stable in the center than in the surface layer on the same class of granule size, whereas more stable for normal barley grain in the surface layer. The results of functionality gave good agreement with the structural parameter in the same origin of starches. The correlations among the functionality and parameter may be represented by a multiple regression equation ( r≥0.9).