Cereal Chem 72:371-378  |  VIEW ARTICLE

Interactions of Sulfur Dioxide, Lactic Acid, and Temperature During Simulated Corn Wet Milling.

D. L. Shandera, A. M. Parkhurst, and D. S. Jackson. Copyright 1995 by the American Association of Cereal Chemists, Inc. 

Response surface methodology was used to investigate the interactions of lactic acid, sulfur dioxide (SO2), and steeping temperature and their effects on corn wet-milling yields. A regular dent and a more vitreous dent corn hybrid were laboratory batch- steeped. Kernel absorption of SO2 was higher for the more vitreous dent hybrid; absorption also increased with lactic acid use and at lower steeping temperatures. Lactic acid concentrations in steepwater remained constant over time, but kernels absorbed more steepwater at higher temperatures. When wet milled on a laboratory scale, vitreous corn was more resistant to grinding and less millable. Significant first-order response surface models of starch, germ, fines, gluten, and steep solids yields were predicted as functions with nonlinear influences of lactic acid and SO2. Higher starch yields were obtained when steeping at 43 C than at 57 C; higher yields were predicted with moderate lactic acid and high SO2 concentrations. Steeping temperature interactions with lactic acid and SO2 during the steeping period limited its integration as a second-order modeling factor for starch, germ, and fines fractions. For all treatments, gluten recovery and steepwater solubles responses were predicted by lactic acid concentrations. Lactic acid, which influenced all significant fraction yield models, affected SO2 absorption.