Distribution of beta-glucan in the grain of hull-less barley

Nine hull-less barley (HB) containing waxy (0-7% amylose), normal (approxim ate to 25g amylose), or high amylose (approximate to 42% amylose) starch wi th normal or fractured granule make-up and 4-9% (1-->3)( 1-->4)-beta-D-gluc ans (beta-glucan) were pearled to remove 70% of the original grain weight i n 10% intervals. The pearled fractions were analyzed for beta-glucan distri bution within HB grain. Protein content of the pearled fractions indicated that the three outermost fractions contained pericarp and testa, aleurone, and subaleurone tissues, respectively For all HB, beta-glucan and acid-extr act viscosity were very low in the outermost 20% of the kernel. For low bet a-glucan HB, beta-glucan content was the greatest in the subaleurone region and declined slightly toward inner layers. For high beta-glucan HB, howeve r, more than 80% of grain beta-glucan was distributed more evenly throughou t the endosperm. Acid extract viscosity was significantly (P < 0.01) correl ated with total (r = 0.75) and soluble (r = 0.87) beta-glucan content throu ghout the kernel of all HB. Growing conditions, location and year, had sign ificant effects on the concentration of protein, starch and beta-glucan. Ho wever, protein, starch, and beta-glucan distribution patterns were not affe cted by growing conditions. The difference in beta-glucan distribution betw een low and high beta-glucan HB may explain the difference in milling perfo rmance of HB with low or high beta-glucan.