DRYING OF HIGH-MOISTURE CORN - CHANGES IN PROPERTIES AND PHYSICAL QUALITY

Corn at 30% moisture was air-dried at 25-100-degrees-C. Drying times t o 12% final moisture ranged from 1 hr at 100-degrees-C to 38 hr at 25- degrees-C. Chemical composition was unchanged by drying temperature. I ncreasing drying temperature decreased test weight, germination, nitro gen solubility index, and it increased kernel breakage susceptibility and percentage of floating kernels. Because breakage susceptibility, b ut not stress-cracking, increased upon high-temperature drying, some c hemical or physical change other than stress-cracking in the kernel ce ll-wall matrix or in the starch granules may have affected breakage su sceptibility. Isoelectric focusing showed decreasing protein bands at pI 4.0-6.6 as corn-drying temperature increased from 70 to 100-degrees -C. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed t hat protein with molecular weights of 21,000-97,000 decreased after tr eatment at 70-degrees-C; they cannot be observed in corn dried at 85-1 00-degrees-C. Prolamin levels also decreased as air-drying temperature increased. Thus, corn density, breakage susceptibility, and germinati on may change upon drying because of changes in albumins and prolamins . These relationships may provide new or improved methods for identify ing grain that is damaged or of lower quality due to high-temperature drying.