Publication no. C-2000-0808-02R |  VIEW ARTICLE

Reducing Steep Time by Adding Lactic Acid During Countercurrent Steeping of Corn with Different Initial Moisture Contents.

P. Yang (1,2) and S. R. Eckhoff (1). (1) Postdoctoral research associate and professor, respectively. Department of Agricultural Engineering, University of Illinois, Urbana, IL 61801. (2) Corresponding author. Fax: (217) 244-0323. E-mail: <p-yang2@uiuc.edu> Cereal Chem. 77(5):529-534. Accepted April 10, 2000. Copyright 2000 American Association of Cereal Chemists, Inc.

Reducing corn steep time by adding lactic acid instead of relying on in situ fermentation was studied. Corn at two initial moisture levels (15 and 20%) was steeped for 18 hr in a countercurrent steep system. The initial SO(2) target concentration in steepwater was 2,000 or 3,000 ppm, while the initial lactic acid concentration in steepwater was 0, 0.28, or 0.55%. Adding lactic acid under all steeping conditions decreased steepwater pH, accelerated SO(2) absorption, and increased the amount of solids released from corn. Adding lactic acid during steeping also increased the first grind slurry density and made germ skimming easier than when no lactic acid was added. Starch yields for the hybrid used in this study under all steep conditions were comparable to those from 24-hr steeping, except when steeping corn with an initial moisture content of 15% in approximately 2,000 ppm of SO(2) alone. For the 20% moisture corn, adding lactic acid to fresh steepwater significantly improved the starch yield at approximately 2,000 ppm of SO(2) for 18-hr steeping. At approximately 3,000 ppm of SO(2), adding lactic acid did not increase the starch yield for the hybrid used. The protein content in starch was significantly lower when lactic acid was added. Pasting properties of starch were not affected by adding lactic acid. The hybrid used in this study had an initial moisture content of 20% and could be wet-milled without affecting starch yield, starch protein content, and pasting properties.