Phytochemical recovery from spent purple corn residues: characterization and process optimization

León-Roque N.; Monteza Arbulú C.A.; Oblitas-Cruz J.F.; Miyagusuku-Cruzado G. · Scientia Agricola (2026) · DOI: 10.1590/1678-992x-2025-0092

Resumen

Purple corn (Zea mays L.) is a rich source of anthocyanins extensively used in the food and cosmetic industry. Producing concentrates and colorants from purple corn generates large amounts of phytochemical-rich byproducts that are not upcycled (spent purple corn cob (sPCC) and spent purple corn grains (sPCG)), which retain significant levels of phytochemicals despite undergoing extensive extraction. sPCC is a fibrous, anthocyanin-rich material, while sPCG contains higher protein and lipid levels. This study aimed to reutilize these byproducts by optimizing extraction yields from sPCC and sPCG using a response surface methodology (RSM) based on phenolic and flavonoid content of the extract. Total phenolics, expressed in mg gallic acid equivalents (GAE) per 100 g of sample, ranged from 1107.5 to 4883.8 in sPCC and from 138.0 to 867.8 in sPCG. Total flavonoids, expressed as mg of quercetin-equivalents per 100 g of sample, ranged from 130.0 to 361.7 in sPCC and from 13.8 to 137.2 in sPCG. Based on phenolic content, optimal conditions were 216.8 min, 80 % aqueous ethanol, and 60 °C for sPCC and 240 min, 80 % aqueous ethanol, and 60 °C for sPCG. Based on flavonoid content, optimal conditions were 60 min, 69.5 % aqueous ethanol, and 30 °C for sPCC and 216.5 min, 80 % aqueous ethanol, and 60 °C for sPCG. Overall, spent purple corn byproducts proved to be valuable sources of phytochemicals, particularly phenolics and flavonoids, successfully recovered under optimized extraction conditions, highlighting their potential for functional ingredients and natural colorants.

Instituciones: Universidad Nacional Pedro Ruiz Gallo; Universidad Privada del Norte