Sulfur dioxide in acid environment facilitates corn steeping
1996
Biss, R. | Cogan, U.
An effective steeping procedure for corn is proposed, using sulfur dioxide under acidic conditions. Corn samples were steeped at 50 degrees C in pH 3.0-5.0 citric acid and sodium citrate buffer solutions containing 2,200 ppm SO2 and 2% sodium chloride. The steeping solutions were refreshed every 5 hr. The highest level of solubilization of corn insoluble proteins was achieved in the steepwater at pH 3.0 and 3.5, with protein degradation ceasing after 20-25 hr. The partition of SO2 between the corn kernel and the steepwater increased markedly with decreasing the pH of the latter. Apparent partition coefficients of SO2 (mean +/- standard deviation) of 2.23 +/- 0.09, 1.64 +/- 0.05, 1.16 +/- 0. 12, and 0.78 +/- 0.06 were obtained for steeping solutions at pH 3.0, 3.5, 4.0, and 5.0, respectively. A mechanism is proposed to explain the effective cleavage of the disulfide bonds of the insoluble glutelin matrix, with the subsequent release of the starch granules by the SO2 under acidic conditions.
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