Abstract
Cornstarch was extruded using various feed moistures and screw speeds with and without soybean oil. We investigated the effects of each variable and interactions between variables on extrudate characteristics. In starch, the positive linear effect of screw speed and the negative effect of the interaction between moisture and screw speed were significant factors in the degree of gelatinization (DG). The positive linear effect of feed moisture and screw speed and their negative interaction were significant factors in the oil-added extrudates. The water absorption index (WAI) of both extrudates was determined by the linear and quadratic effect of feed moisture and the negative interaction between the two variables. In starch, the positive quadratic effect of moisture and screw speed and their negative interaction affected the water solubility index (WSI). In the oil-added extrudates, the negative effect of feed moisture and the negative interaction of screw speed and feed moisture influenced WSI.
