Cereal Chem. 73 (5):632-637 |
Effect of Corn Wet-Milling Conditions (Sulfur Dioxide, Lactic Acid, and Steeping Temperature) on Starch Functionality (1).
D. L. Shandera (2) and D. S. Jackson (3). (1) Journal Series 11340, Agricultural Research Division, Institute of Agriculture and Natural Resources, University of Nebraska-Lincoln (2) Graduate research assistant, Cereal/Oilseed Science & Technology Laboratory, Dept. of Food Science & Technology, University of Nebraska-Lincoln. (3) Associate professor, Cereal/Oilseed Science & Technology Laboratory, Dept. of Food Science & Technology, University of Nebraska-Lincoln, Lincoln, NE 68583-0919. Corresponding author. E-mail: <djackson@UNL.edu> Accepted May 13, 1996. Copyright 1996 by the American Association of Cereal Chemists, Inc.
Starch functional characteristics varied with wet-milled corn steeping temperature and concentrations of lactic acid and sulfur dioxide. Starch was laboratory-wet-milled from Golden Harvest 2572, a medium-hard yellow dent corn hybrid. Batch steeping levels of temperature (43 and 57°C), lactic acid concentration (0.2 and 1.5%, v/v), and sulfur dioxide concentration (0.05 and 0.30%, v/v) were assigned in a 2(^3) factorial experiment. Starch milled from corn steeped with 1.5% lactic acid at 57°C had reduced Brabender Viscoamylograph pasting, shear thinning, and set-back viscosities. These starches also had increased water solubility as measured by high-performance size-exclusion chromatography. Solubilized in 90% methyl sulfoxide, starch from corn steeped at 57°C with 1.5% lactic acid or 0.30% sulfur dioxide (SO(2)) had lowered resistance to shear as evident in formation of smaller molecular sized polymers. Higher differential scanning calorimetry endotherm peak start, onset, and peak maximum temperatures were observed for starch obtained from corn steeped at 57°C or with 0.2% lactic acid. Endotherms were also narrower for steeping at 57°C than at 43°C. When viewed by scanning electron microscopy, more surface irregularities were present on starch granules from corn steeped at 57°C and 1.5% lactic acid than those from corn steeped at 43°C or 0.2% lactic acid.