Changes in physicochemical properties of waxy corn starches after harvest, and in mechanical properties of fresh cooked kernels during storage

• Starch content in all genotypes increased as a function of time after harvest.
• Starch granules continued to develop after harvesting.
• Average chain length distribution of amylopectin increased in relation to storage time.
• Waxy corn starches at harvesting stage exhibited the lowest peak viscosity, which then increased relation to storage period.
• Mechanical properties of fresh cooked kernels showed an average force related to time after cooking.

Changes in the physicochemical properties of waxy corn starches after harvest and in the mechanical properties of cooked fresh kernels during storage were investigated. Immature waxy corn ears from four genotypes were stored at ambient temperature, and starches were isolated from kernels removed at 0, 2, 4 and 6 days after harvest. Starch content in the kernels generally increased with storage time, and also significantly differed depending on the genotype. For all the days after harvest, medium granules had the highest contribution to the total starch volume, followed by small and large granules. The average chain length distribution of amylopectin increased in relation to storage time. Starches at harvesting state exhibited the lowest peak viscosity in all four genotypes, which increased relative to postharvest periods. Moreover, the average force behaviours of cooked kernels were greatly affected by storage times after cooking.