Interaction effects of milling variables on durum wheat in the first break system
2001
Hareland, G.A. (United States Dept. of Agriculture (USDA), Fargo (USA). Agricultural Research Service) | Shi, Y. (Buehler Inc., Minneapolis (USA))
Interactions among five major milling variables (flute angle, number of corrugations, flute orientation, speed differential of the grinding rolls and wheat moisture) were investigated from the 'first break' products of a pilot-scale durum mill. A complete factorial design was arranged for statistical analysis. Within the boundaries of the variables, two-way analysis of variance showed that the true interactions of angle/orientation, corrugation/orientation and speed differential/orientation had significant (P0.01) effects on the first break release sifted through a 14 W (1,371 micronm) sieve and on the semolina and flour yields. Dull-to-dull orientation resulted in the highest break release and the highest semolina and flour yields when the flute angle profiles were 45 deg/60 deg and the corrugations were 8 flutes/inch of roll surface. In comparison, sharp-to-sharp orientation resulted in the highest break release and the highest semolina and flour yields when the flute angle profiles were 25 deg/65 deg. Sharp-to-dull orientation resulted in the highest semolina and lowest flour yields when the speed differential of the rolls was 1.5:1. Wheat moisture content was independent of any true interactions, but its influence was significant (P0.01) on first break yields. Tempered wheat moisture content was positively correlated to the yield of the top coarse milled fraction and negatively correlated to the yields of the finer milled fractions. A comparison between dull-to-sharp and sharp-to-dull grinding orientations showed that product yield with these mill settings were similar
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