The effect of protease addition on starch recovery from steeped white regular sorghum (RSOR) compared to yellow maize (YMZ) was determined. An in vitro wet milling method standardized to test dosages from 0 to 1.5 Anson units (AU/100 g grain) indicated that starch yields increased proportionally as enzyme concentration increased. The yields were significantly lower for RSOR. A factorial experiment with a level of confidence of P < 0.05 was performed to study the effect of protease addition (1.25 AU/100 g grain) to coarsely ground kernels for 4 h after 20 h or 44 h SO2 steeping of whole grains. Calcium oxide (CaO) was used to increase the pH of the steep solution to 5.5 and improve enzyme activity. The in vitro and laboratory tests indicated that the enzyme treatment significantly improved starch yields and recoveries; the effect being more pronounced in RSOR. Protease‐treated kernels yielded 3.2% more starch than those steeped regularly. RSOR steeped for 20 h and then treated with the enzyme for 4 h yielded 6.7% more starch than the counterparts steeped regularly. When steep times were compared, kernels soaked regularly for 48 h produced 1.6% more starch than counterparts steeped for 24 h. The protease treatment reduced the amount of inseparables (gluten‐starch complexes) to zero and also lowered the gluten content of starch by about 1.5%. A comparison of protein and ash contents for the refined starches indicated that the process was more efficient for YMZ than for RSOR and for grains steeped regularly for 48 h. YMZ starch started gelatinization at a lower temperature, required less time to reach peak viscosity and had less shear thinning than RSOR.

The effect of a commercial cell‐wall‐degrading enzyme (CWDE) complex on the steeping time and starch yields of white regular sorghum (RSOR) compared with yellow maize (YMZ) was determined. An in vitro wet‐milling method standardized to test dosages of 0–120 fungal β‐glucanase units (FBG)/100 mL indicated that starch yields were significantly higher for YMZ than RSOR and increased proportionally as enzyme dosage increased. A factorial experiment with a level of confidence of P < 0.05 was performed to study the effect of CWDE addition to coarsely ground grains for 4 hr after 20 or 44 hr of SO2 steeping of whole grains. At both regular steep times, YMZ yielded significantly higher amounts of starch than RSOR. When steep times were compared, grains soaked for 48 hr produced 1.7% higher starch yields than counterparts treated for 24 hr. CWDE significantly increased starch yields and recoveries. Enzyme‐treated grains yielded 2.5% more starch than counterparts steeped regularly. For both grains, the best wet‐milling conditions to obtain the highest amount of starch were 48 hr of steeping and CWDE addition. Under these conditions, YMZ and RSOR yielded 66.9 and 66.6% starch, respectively. Starches obtained after the enzyme treatment at both steep times contained higher amounts of residual protein and ash compared with the untreated counterparts. Rapid viscoamylograph properties of YMZ and RSOR starches were not affected by the use of the CWDE nor the steep time. In comparison with RSOR starch, the YMZ starch initiated gelatinization at lower temperature, had less shear thinning and higher viscosity or setback at the end of cooling.