Effects of maturity on corn starch properties

The effect of maturity on the quality of starch for two corn hybrids harvested at three different stages of development was measured by differential scanning calorimetry, rapid viscosity analysis, scanning electron microscopy, and image analysis. The onset of gelatinization and peak temperatures were 2-5degreesC higher for starch from immature grain than starch from mature grain. The gelatinization temperature range was 5degreesC larger as the grain matured. Peak and trough viscosities decreased with maturity, while pasting temperature increased. Between the two hybrids, the late maturing hybrid yielded a larger peak viscosity and trough. The early maturing hybrid exhibited a higher pasting temperature. Image analysis data showed that the starch granules from mature grain showed an increase in size compared with the starch granules from grain that were harvested at the late milk line stage for one, but not both hybrids.