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.

Corn (Zea mays L.) provides a major source of calories for human consumption and therefore, the nutritional components of corn have a large impact on human health. For example, corn kernels contain antioxidants, such as polyphenols (including anthocyanins and other flavonoids) and carotenoids. Such compounds represent useful targets for biofortification breeding. In this study, we used 34 corn inbred lines from three different regions (East Asia, Southern Asia, and subtropical regions) and 11 F1 hybrids derived from the inbreds to investigate antioxidant activity in yellow corn. We compared different methods for measuring antioxidant activity to test their consistency and to determine whether color could be used as an indicator of antioxidant activity. We also measured carotenoid levels in yellow corn. No difference in antioxidant activity was detected between inbred corn lines from temperate vs. tropical regions. We determined that carotenoid is a major contributor to antioxidant activity in yellow corn and that kernel color, especially yellowness, could be used as an indicator of antioxidant activity in yellow corn. These findings lay the foundation for the biofortification of yellow corn by providing information about the correlations among kernel color, carotenoid contents, and antioxidant activity and by identifying an easy method to assess antioxidant activity in yellow corn.

Phytosterols are important structural components of plant cells that affect membrane fluidity, permeability, and membrane-related metabolic regulation. These compounds, which are abundant in vegetable oils and corn kernel oil, are also beneficial for human health. Cultivation of corn (Zea mays L.) produces huge amounts of cobs as a by-product, but efforts to utilize cobs are still limited. Here, we investigated phytosterol, crude oil, and fatty acid contents in the kernels and cobs of four major corn cultivars in South Korea and explored the potential use of cobs as a source of phytosterols. Total phytosterol levels were two times higher in cobs (68.0–217.1 mg 100 g−1 DW) than in kernels (43.8–89.5 mg 100 g−1 DW) and were highest in the kernels and cobs of Sinhwangok at 60 days after pollination. We showed that not only kernels but also cobs can be a rich source of phytosterols. The results also revealed that the amount of phytosterol is depending on a genetic background as well as developmental stages suggesting further investigation would enhance the utilization of corn cobs as a phytosterol source.

KM2', a maize hybrid grain was developed for the Southeast Asian seed market by the maize breeding team of the Rural Development Administration (RDA), South Korea 2018. 'KM2' was bred by crossing two inbred lines, '15VL065' and 'KS155'. After a advanced yield trial at Dong Trieu, Vietnam, for the first cropping cycle in 2016, country adaptability trials were performed twice in three different countries: Vietnam, Cambodia, and Indonesia, in 2016 and 2017. 'KM2', a yellow intermediate seed for food and feed, adapts well to the northern Vietnam, northwestern Cambodia, and Central Java in Indonesia. It is an early maturing high-grain yield F1 hybrid. This hybrid is resistant to downy mildew, but not corn rust. The silking date of 'KM2' is 10 days earlier than that of 'LVN10', a leading cultivar in Vietnam. 'KM2' produced grain yields of 811 kg/10a, 845 kg/10a, and 783 kg/10a in Vietnam, Cambodia, and Indonesia, respectively, showing even higher grain yield than the countries' respective leading cultivar. 'KM2' produced 61%, 17%, and 14% higher grain yield in Vietnam, Cambodia, and Indonesia, respectively, than their respective control cultivars ('LVN10', 'CP888', 'P21') (Registration No. 8192).