Purple corn (Zea mays L.) is used for the preparation of traditional drinks and desserts, generating great quantities of residues. The scarce information about purple corn cob (PCC) is encouraging an interest in exploring its potential as a valuable source of bioactive compounds with benefits for human health. In this study, a green method based on hydrothermal processing was used for the simultaneous extraction of oligosaccharides and phenolic compounds from PCC. For this purpose, the effects of three factors (time, temperature and pH) on the oligosaccharide content (OSC), total phenolic content (TPC), total flavonoid content (TFC), total anthocyanin content (TAC), as well as on the antioxidant activity measured with three different methods (DPPH, ABTS and FRAP) were evaluated. The bioactive extract obtained under optimal conditions presented a high content of bioactive compounds exhibiting a notable antioxidant capacity and moderate inhibitory activities towards xanthine oxidase. This extract was also structurally characterized by FTIR, HPAEC-DAD, MALDI-TOF-MS and TGA, and the HPLC-ESI-MS analysis led to the tentative identification of 15 antioxidant phenolic compounds. Thus, this research demonstrated that this residue from the food industry has a high potential for obtaining several bioactive compounds that can be utilized as multi-functional ingredients in the food and pharmaceutical industries.
Keywords: Anthocyanins; Antioxidant phenolics; Hydrothermal treatment; Oligosaccharides; Purple corn cob.
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