Effects of Heat Stress During Grain Filling on the Functional Properties of Flour from Fresh Waxy Maize

The effects of temperature during grain filling on the quality of fresh waxy maize grain were investigated using three varieties. Plants of the selected varieties were subjected to two temperature treatments, namely, control (mean daily air temperature, 30 degrees C) and heat stress (35 degrees C), after artificial pollination (1-23 days after pollination). Heat stress decreased starch content and crystallinity and increased the contents of protein and protein fractions (albumin, globulin, zein, and glutenin), but it did not affect soluble sugar content in general. The effects of heat stress on grain textural characteristics were variety dependent, except for springiness, which was similar between treatments. Pasting and thermal properties were also affected by heat stress. The results suggest that heat stress during grain filling changes the composition of flour and crystalline structure of starch, thereby decreasing viscosities and enthalpies of gelatinization as well as increasing the pasting and gelatinization temperature of fresh waxy maize.