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Roller Milling of Canadian Hull-less Barley: Optimization of Roller Milling Conditions and Composition of Mill Streams

¹Canadian Grain Commission, Grain Research Laboratory, 1404-303 Main St., Winnipeg, MB, R3C 3G8, Canada. Contribution no. 292. ²Corresponding author. Phone: 204-983-1300. Fax: 204-983-0724. E-mail: mizydorczyk@grainscanada.gc.ca. ³Crop Development Centre, University of Saskatchewan, Saskatoon, SK, S7N 5A8, Canada. ⁴Dept. Food Science, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada.

Roller milling of hull-less barley generates mill streams with highly variable β-glucan and arabinoxylan (AX) content. For high β-glucan cultivars, yields >20% (whole barley basis) of a fiber-rich fraction (FRF) with β-glucan contents >15% can be readily obtained with a simple short mill flow. Hull-less barley cultivars with high β-glucan content require higher power consumption during roller milling than normal β-glucan barley. Recovery of flour from high β-glucan cultivars was greatly expedited by impact passages after grinding, particularly after reduction roll passages. Pearling before roller milling reduces flour yield and FRF yield on a whole unpearled barley basis, but flour brightness is improved and concentration of β-glucan in fiber-rich fractions increases. Pearling by-products are rich in AX. Pearling to 15–20% is the best compromise between flour and FRF yield and flour brightness and pearling by-products AX content. Increasing conditioning moisture from 12.5 to 14.5% strongly improved flour brightness with only a moderate loss of flour yield on a whole unpearled barley basis. As moisture content was increased to 16.5%, flour yield declined without a compensating improvement in brightness, but the yield of fiber-rich fraction continued to increase and concentration of β-glucan in FRF also increased.