ABSTRACT
The objectives of this research were to study the effects of slurry specific gravity, starch table slope, slurry pumping rate, and their interactions on starch recovery and purity; and to propose a small-scale laboratory wet-milling procedure for wheat. First-order and second-order response surface regression models were developed to study the effects and interactions of slurry specific gravity, starch table slope, and slurry pumping rate on starch and gluten separation for a 100-g wheat wet-milling procedure. The starch and starch protein content data fit the first-order models (R2 = 0.99 and 0.96) better than the second-order models (R2 = 0.98 and 0.93). Regression results from the first-order models indicated that specific gravity, table slope, pumping rate, and their interactions all had a significant effect on starch yield and purity. However, these effects could be simplified as the effect of the resident time of starch and gluten slurry on the starch table and the specific gravity. Starch yield increased as resident time increased and specific gravity decreased. Protein content in starch decreased as the resident time decreased and the specific gravity increased. The separation condition with specific gravity of 3 Bé, table slope of 1.04 cm/m, and pumping rate of 50 mL/min was recommended. Under this condition, starch recovery was 85.6% and protein content of starch was 0.42%, which was similar to the 1.5-kg laboratory methods in starch recovery. Total solids recovery was 98.1%, which is similar to that from 1.5-kg laboratory methods. These results indicated that precision of the 100-g wheat wet-milling procedure was similar to that of the 1.5-kg laboratory methods.
