2001 AACC Annual Meeting Charlotte, North Carolina October 14-18, 2001 Charlotte Convention Center

The purpose of this study was to determine the distribution and structural features of NSP in milling fractions of hull-less barley. Three genotypes with variable amylose content (high amylose, normal, and waxy) were pearled (10%) and milled to produce pearling by-product (PB), straight grade flour (SGF), and shorts. PB contained the highest amount of arabinoxylans whereas shorts were enriched in both, beta-glucans and arabinoxylans (AX). NSP were sequentially extracted from the milling streams with water, saturated barium hydroxide (Ba(OH)(2)), neutralized water (H(2)O), and sodium hydroxide (NaOH). The water-extractable fraction from PB contained primarily AX, followed by beta-glucans and arabinogalactans. AX in PB from normal barley had the highest degree of branching. All alkali-extractable fractions from PB contained mostly AX. Water-extractable fractions from SGF and shorts contained 75-90% beta-glucans and 10-22% AX. In contrast to all alkali-extractable fractions from PB, the H(2)O and NaOH fractions from SGF and shorts consisted mainly of beta-glucans. (^1)H-NMR analysis revealed differences in the substitution patterns among AX from various milling fractions. The xylose to arabinose ratio in water-extractable AX from PB was lower than in water-extractable AX from SGF and shorts, indicating that the degree of branching decreased from the outside towards the center of the kernel. Lichenase hydrolysis of water extractable fractions from various milling streams indicated differences in the ratio of tri- to tetra-saccharides in beta-glucans.