Effects of alkali debranning, roller mill cracking and gap setting, and alkali steeping conditions on milling yields from a dent corn hybrid

Starch yield was significantly affected by all three main unit operations i n alkali wet-milling (debranning, roller milling, and steeping). The condit ions for the three unit operations were studied using a single hybrid. Stud ies on debranning showed that optimal separation between pericarp and corn endosperm was obtained when corn was soaked in a 1.5-2% NaOH solution at 85 degrees C for 5 min. Passing debranned corn through a smooth roller mill o nce or twice did not affect the product yields, but passing the corn throug h the roller mill three times decreased the germ yield because of a large a mount of broken germ. A 62% higher processing rate could be achieved when p assing corn through the mill twice than by passing it through the mill once . The gap should be set at 2.0 mm when passing corn through the mill once, and it should be set at 3.5 mm for the first pass and 2.0 mm for the second pass when passing corn through the mill twice. Starch yield was more sensi tive to NaOH concentration and steep temperature than to steep time. The hi ghest starch yield was obtained when steeping corn in 0.5% NaOH for 1 hr at 45 degrees C.