2001 AACC Annual Meeting Charlotte, North Carolina October 14-18, 2001 Charlotte Convention Center

The objective was to investigate the thermal properties of the opaque and translucent endosperm sections of corn. Corn kernels were soaked either in excess water or 0.5% NaHSO(3) at 30°C, 40°C, 50°C, or 60°C for 48 hr in a water bath. The pericarp and germ were then removed by hand using a tweezer. The opaque endosperm was separated from the translucent endosperm using a sharp spatula. A third section, termed intermediate endosperm, was distinguished as the flour obtained following grinding of the translucent endosperm. The thermal characteristics of the endosperm sections following the different treatments were compared using Differential Scanning Calorimetry. The protein content of these samples was also determined using a Leco Nitrogen Analyzer. The protein content was greater in the translucent and intermediate endosperm fractions compared to the opaque endosperm. Starch annealing was observed in all endosperm fractions as the soaking temperature increased. The range of gelatinization at 30°C was different for the three endosperm fractions and the range decreased at a much faster rate for the translucent endosperm compared to the opaque endosperm. The opaque endosperm fraction had a greater enthalpy of gelatinization compared to the intermediate or the translucent endosperms. It is hypothesized that the differences in protein solubility in the two soaking solutions, the interaction between starch and protein and possibly even differences in starch structures in the three endosperm sections contributed to the apparent differences observed.