Evaluation of dry milling characteristics and polyphenolic contents of fourteen conventionally bred colored corn varieties for value-added coproducts recovery

Authors: KUMAR, RAVINDER - University Of Missouri; AGLIATA, JOSEPH - University Of Missouri; WAN, CAIXIA - University Of Missouri; Flint-Garcia, Sherry; SALAZAR-VIDAL, MIRIAM - University Of Missouri; MUSTAPHA, AZLIN - University Of Missouri; CHENG, JIAYUE - University Of Missouri; SOMAVAT, PAVEL - University Of Missouri

Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/20/2024
Publication Date: 9/1/2024
Citation: Kumar, R., Agliata, J., Wan, C., Flint Garcia, S.A., Salazar-Vidal, M.N., Mustapha, A., Cheng, J., Somavat, P. 2024. Evaluation of dry milling characteristics and polyphenolic contents of fourteen conventionally bred colored corn varieties for value-added coproducts recovery. Industrial Crops and Products. 215. https://doi.org/10.1016/j.indcrop.2024.118600.
DOI: https://doi.org/10.1016/j.indcrop.2024.118600

Interpretive Summary: Corn grain is primarily used in the US for animal feed and ethanol fuel production. During processing via dry milling, the grain is broken down into several fractions which contain varying levels of phytochemicals. The outside layer of the kernel, called the pericarp, is a low value by product but contains a number of bioactive compounds that could be increased by traditional breeding methods in order to add value to the US corn crop. In this study, we explored the dry milling characteristics and phytochemical profiles of 14 experimental varieties with blue, red, and purple kernels, and compared them to a standard variety with intense purple pigmentation that was characterized previously. All 14 experimental varieties were found acceptable for milling, but generally had less starch and more protein than yellow dent corn. Four of the experimental varieties had pericarp tissues with high levels of polyphenols including a diverse mix of anthocyanin pigments, phenolic acids, and flavonoids. This information will be useful to corn geneticists and breeders as they develop pigmented corn varieties and to processors as they develop methods to extract high value phytochemicals to add value to the US corn crop.

Technical Abstract: Corn pericarp is a low value cellulosic coproduct. However, colored corn pericarp contains disproportionately higher amounts of polyphenolic compounds such as anthocyanins, flavonoids, flavonols, tannins and phenolic acids, and can be selectively utilized for their economic recovery. Due to the diverse industrial applications of these value-added phytochemicals, colored corn can supplement the lower economic value of conventional yellow dent corn. In this study, dry milling characteristics and polyphenolic contents (anthocyanins, total phenols, and condensed tannins) of fourteen conventionally bred and midwestern US grown colored varieties and their milling coproducts were ascertained and compared with a commercial purple corn. With mean large grits yield of 22.98% (db), colored varieties had a dominant softer endosperm, suitable for wet milling and dry grind industry. The mean starch content of colored varieties was lower than conventional yellow dent corn (~9.91%, db), and the mean protein content was higher (~1.70%, db). Although purple corn contained the highest amounts, four experimental varieties had high concentrations of polyphenols. Through HPLC analyses, a diverse mix of various anthocyanin forms, phenolic acids, and flavonoids were identified. The antioxidant potential of polyphenolic extracts from five varieties were evaluated using four different assays, and significant antioxidant activities were observed. Histological analysis was conducted on polyphenol-rich varieties, and most of the pigments were found to be concentrated in pericarp. The pericarp thickness was greatest for the variety containing the maximum polyphenolic compounds. Adapted colored corn varieties can be valorised to recover value-added polyphenolic compounds in line with the circular bioeconomic paradigm.