Identification and Evaluation of Antioxidant Activity of Hydroxycinnamic Acids Extracted by Ultrafiltration from Three Varieties of Mexican Maize

The identification and quantification of phenolic components separated by ultrafiltration from the alkaline cooking water of three varieties of Mexican maize (white, red and purple) were performed. The total content of polyphenols and the antioxidant activity of the permeate was evaluated. The cooking water (Nejayote) obtained from the nixtamalization process was subjected to a consecutive fractionation process with three membranes of different molecular cutting (MF-UF100-UF1) for the recovery of bioactive components. The highest content of total polyphenols recovered in the fractions was with the integrated MF-UF100 process (UF100-Permeate of white maize, red maize and purple maize) with values of 768.22, 800.72 and 776.88 mg GAE L-1, respectively; and the antioxidant activity in the same fractions was 0.43, 0.33 and 0.33 TE mL(-1), respectively. The UHPLC-ESI-MS showed that the hydroxycinnamic acids present at the end of the initial process proposed (MF-UF100-UF1) were ferulic acid and p-coumaric acid; those that were present in the fractions of UF1-Permeate (of white corn, red corn and purple corn) in quantities of 99.89, 138.85 and 211.03 mg L-1, of ferulic acid respectively and p-coumaric acid in amounts of 24.56, 31.88 and 76.21 mg L-1, respectively. The results allow us to visualize possible applications in food industry (bakery products and pastry, mainly) for extracts from Nejayote.