Amaranth grains (Amaranthus cruentus) were air-dried at 40, 70 and 100 ºC and a moisture range from 29.5 to 10.2, dry basis (d.b.). Dried grains were wet-milled at 53.9ºC in the presence of SO2 aqueous solution in order to obtain fractions of starch, protein and fiber. Effect of drying temperature and SO2 concentration (0.01 0.05 w/v %) on fraction yields and protein content of starch were investigated using response surface method (RSM). A factorial design including triplicate of central point was performed. Starch and protein yields decreased as drying temperature increased while fiber yield and protein content in starch fraction shown the opposite behaviour. Protein yield and protein in starch fraction were affected negatively by SO2 concentration. Interaction among studied factors was only appreciable in fiber yield where a synergic effect was observed. The optimum conditions required to maximize starch together with the minimization of protein content in starch fraction included drying temperature of 40°C with amaranth soaking using 0.05 w/v % of SO2. These process conditions lead to 35.1 ± 1.4% of starch yield with a protein content of 1.93 ± 0.015%.
Wet milling characteristics of corn mutants using modified processes and improving starch yields from high amylose corn