PHYSICOCHEMICAL PROPERTIES OF ROLLER-MILLED BARLEY BRAN AND FLOUR

Grain hardness, determined by grind time in 16 diverse barleys, showed waxy starch (low amylose) genotypes to be softer (grind time 39-64 sec) than the normal starch genotypes. Bran and flour obtained from the 16 barleys, milled in an Allis-Chalmer experimental mill, showed significant differences in bran and flour color (white) among varieties. Bran and flour milled from Scout, a registered two-rowed Canadian hull-less barley, were compared for physicochemical properties with commercial oat bran and straight-grade wheat flour. Barley bran was whiter than oat bran. It had, like oat bran, high water-holding capacity (WHC) due to its high beta-glucan (7.7%) content. Barley bran had 20% total dietary fiber (TDF) and 7% soluble fiber (SF) compared to 14% TDF and 5% SF in oat bran. The ratio of SF to TDF in barley bran, as in oat bran, was 1:3. Barley flour was darker than wheat flour but had higher WHC (2.5-fold), farinograph absorption (75%), and viscoamylograph peak viscosity (660 BU). Barley flour had higher ash (1.8%), ether extract (2.5%), beta-glucan (4.5%), TDF (8.7%), SF (2.7%), and insoluble fiber (4.7%) than wheat flour. The ratio of SF to TDF was 1:3 in barley flour and 1:2 in wheat flour. Phosphorus and potassium were the major minerals, and iron and zinc were the major trace minerals of Buhler-milled Scout barley flour. Beta-Glucan and pentosans were the major components; resistant starch, Klason lignin (only TDF), and pectin were the minor components of TDF and SF of barley bran and flour.