Effects of drying and heating conditions on protein denaturation, starch damage and protease activity of corn: Its relationship to wet millabilit

Laboratory heated and dried yellow dent corn was investigated in three parts for this study. The first part determined the effects of moisture content, heating time, and temperature on starch damage (gelatinization) and protein denaturation of individual corn kernels. For different genotypes, starch damage was found to increase as kernel temperatures, harvest moisture and heating time increased; hard genotypes showed more distorted granules than the soft genotype. Ethanol soluble protein in corn decreased as kernel temperatures, harvest moisture and heating time increased. Kernel temperatures and heating time are two major factors affecting albumin and globulin denaturation. However, the harvest moisture content did not significantly affect the denaturation of these albumin and globulin.;The second part involved the determination of the effects of drying temperature on wet millability. Based on statistical analysis, the recovery of starch decreased significantly as the drying air temperature increased; the denaturation of proteins, starch gelatinization and starch-protein interaction were factors which also reduced starch recovery. Addition of the protease improved the separation of protein which was attached to the cell wall in the endosperm.;The last part was the observation of microstructural changes in floury and corneous endosperm due to drying temperature and harvest moisture. There was more starch granule damage in the corneous endosperm than in the floury endosperm in the same corn genotype; slightly more starch damage occurred in the hard genotype than in the soft genotype.