Wet milling characteristics of corn mutants using modified processes and improving starch yields from high amylose corn

Yellow dent, high amylose and waxy corn were evaluated using lab-scale conventional, enzymatic (E-milling) and intermittent milling and dynamic steeping (IMDS) processes. The application of proteolytic enzyme (E-milling) and sulfur dioxide (Conventional milling and IMDS process) during kernel hydration and their effects on overall starch yields from three corn types were studied. Despite using lower amount of SO₂ (600 ppm) and shorter steeping duration (66.8%), E-milling yielded the highest amount of starch for yellow dent, high amylose and waxy corn (71.4%, 60.1% and 66.9% (db), respectively). The use of proteolytic enzyme during steeping resulted in 26.1% points higher starch yield for high amylose corn. In conventional wet milling process, the highest starch yields were obtained from yellow dent corn and the lowest from high amylose corn, the values being 70.1% and 46.2% (db), respectively. Similarly, highest starch yield (69.5%, db) was obtained from yellow dent corn from the IMDS process. Steepwater absorption for high amylose corn was on average 37.7% greater than the other two corn types for conventional process and 34.6% greater for the modified processes. Modified wet milling protocols with shorter steeping durations and requiring lesser amounts of SO₂ can be used to efficiently process different corn mutants.