Optimized methodology for the extraction of free and bound phenolic acids from Chilean Cristalino corn (Zea mays L.) accession

The aim of this study was to optimize the extraction of free and bound phenolic acids from Chilean Cristalino corn by response surface methodology based on the total phenolic contents (TPCs) and the 2,2-diphenyl-1-picrylhydrazyl scavenging-linked antioxidant capacity (AC) as response variables. Central Composite 22 + axial points experimental designs were applied. The best extraction conditions for the free and bound phenolic fraction were acetone 69% in water for 63 min and a hydrolysis with 3 M NaOH for 90 min, respectively. Under these conditions, TPCs in free and bound forms were 59.9 ± 0.7 and 172.9 ± 1.1 mg gallic acid equivalents/100 g, respectively. Further, AC found in free and bound fractions was 186 ± 3 and 694.5 ± 3.3 µmol Trolox equivalents/100 g, respectively. The experimental and predicted values of TPC and AC were similar in case of free phenolic fraction indicating that the model was adequate and reproducible. Major phenolic acids were found in the bound fraction and were ferulic and p-coumaric acids.