Cereal Chem. 73 (1):40-44 |
Nonwheat Grains and Products
Sulfur Dioxide in Acid Environment Facilitates Corn Steeping.
Rachel Biss (1) and Uri Cogan (2). (1) Galam Ltd., Menashe Post, 37855, Israel. (2) Corresponding author. Department of Food Engineering and Biotechnology Technion, Haifa 32000, Israel. E-mail: <firstname.lastname@example.org> Accepted October 20, 1995. Copyright 1996 by the American Association of Cereal Chemists, Inc.
An effective steeping procedure for corn is proposed, using sulfur dioxide under acidic conditions. Corn samples were steeped at 50°C in pH 3.0-5.0 citric acid and sodium citrate buffer solutions containing 2,200 ppm SO(2) 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 SO(2) between the corn kernel and the steepwater increased markedly with decreasing the pH of the latter. Apparent partition coefficients of SO(2) (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 SO(2) under acidic conditions.