Cereal Chem 68:248-251   |  VIEW ARTICLE

Wet Milling of Corn Using Gaseous SO2 Addition Before Steeping and the Effect of Lactic Acid on Steeping.

S. R. Eckhoff and C. C. Tso. Copyright 1991 by the American Association of Cereal Chemists, Inc. 

Gaseous SO2 was applied to low-moisture corn kernels (Dekalb 636) at rates of 0.1 and 0.2% (based upon the weight of steepwater) before steeping for 6, 12, or 24 hr. These gas-treated samples were compared to a standard 48-hr control steep using the same sulfite levels. At the 0.1% treatment level, the effect of adding 0.55% lactic acid to the steepwater was studied. Starch yields of the controls were not statistically different from those of the 12-hr steeps. Brabender consistency was approximately 12% higher for the gas-treated samples at 12 hr than for the controls. The 6-hr gas-treated corn had even higher Brabender consistencies, but starch yields were decreased by approximately 3% at all treatment levels. Increasing the concentration level of gaseous SO2 from 0.1 to 0.2% resulted in increases in starch yields of 1.44, 2.08, and 2.35% for the 6-, 12-, and 24-hr steeps, respectively. The role of lactic acid in increasing starch yields was demonstrated. Starch yields from 0.1% SO2 plus 0.55% lactic acid were greater than those from 0.2% SO2 without lactic acid for all steep times. Starch yields were increased by 5.64, 4.96, and 4.44% for the 6-, 12-, and 24-hr steeps, respectively, for the 0.1% treatment level. Protein contents of the starch were acceptable for all treatments (less than 0.413%).