Timing and Pattern of Anthocyanin Accumulation during Grain Filling in Purple Waxy Corn ( Zea mays L.) Suggest Optimal Harvest Dates

Purple-corn kernels contain anthocyanins, a group of antioxidants proposed to be beneficial to human health. This study investigated the concentrations of anthocyanins and amino acids and the composition of fatty acids in the kernels of purple waxy corn (Zea mays L.) "Heukjinjuchal" during grain filling to determine when the grain nutritional value is at its highest. During grain filling, anthocyanin contents increased as the kernel color darkened. Among the anthocyanins measured, cyanidin-3-β-O-glucoside reached the highest contents, 57.0-409.1 mg kg^-1 fresh weight in raw kernels and 1027.6 mg kg^-1 in dry seeds. Pelargonidin-3-β-O-glucoside and malvidin-3-β-O-glucoside became detectable at 21 days after silking; they occurred in the second- and third-highest amounts, respectively, among anthocyanins in the purple-corn cultivars tested. The anthocyanin accumulation pattern was strongly associated with physicochemical properties and partly associated with amino acid content. Anthocyanin contents increased in a stepwise rather than linear fashion. This study showed that kernels undergo dramatic changes that affect the nutritional value of fresh corn.