Cereal Chem 52:779 - 790. | VIEW
Corn Proteins: Chemical and Physical Changes During Drying of Grain.
J. S. Wall, C. James, and G. L. Donaldson. Copyright 1975 by the American Association of Cereal Chemists, Inc.
Changes in proteins in high-moisture corn dried at elevated temperatures were investigated to determine reasons for previously reported reduced grain quality for seed, milling, and feed uses. Grain harvested at 25% moisture was dried to about 15% moisture by heating at air temperatures ranging from 15 to 143 C in a forced-air dryer. Proteins were sequentially extracted from defatted grain or endosperm meals with various solvents. Amounts of proteins extracted with 0.5N NaCl were markedly reduced in meals heated to 143 C, and their electrophoretic patterns changed significantly. A smaller decrease occurred in yield of zein extracted with 70% ethanol-0.5% sodium acetate. Buffer containing 0.5% sodium dodecyl sulfate (SDS) dissolved some of the unsolubilized protein. Increased solubility in 0.5% SDS solution containing mercaptoethanol of proteins of corn dried with 143 C air indicated that intermolecular disulfide bonds are formed during heating. The number of sulhydryl groups decreased during heating of whole grain; a parallel decrease occurred in grain viability. Lysine and available lysine contents were reduced slightly by heating at the highest temperature.