Optimization of the antioxidant polyphenolic compounds extraction of yellow passion fruit seeds (Passiflora edulis Sims) by response surface methodology

The conditions for the solid–liquid extraction of the antioxidant polyphenol compounds from yellow passion fruit seeds were optimized by response surface methodology with the following variables as the extraction parameters: extraction time (12.8–147.2 min), ethanol concentration (13–97%), and temperature (16.4–83.6 °C). The polyphenol content and antioxidant capacity, which were assessed by the 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity, oxygen radical absorbance capacity, β-carotene bleaching assay, and ferric reducing antioxidant power assay, were considered dependent variables. The association of the dependent variables was effective for explaining the effect of the independent variables within a determination coefficient (R2) range of 0.88–0.96. A moderate-to-strong correlation for the polyphenol content and antioxidant capacity by the investigated methods was established, and optimized conditions were employed to maximize this response. Extraction was carried out at 80 °C using 70% ethanol concentration for 30 min, which was the most efficient condition to obtain an extract with high concentrations of polyphenolic compounds (3.12 g gallic acid equivalent/100 g seed dry basis) and a strong antioxidant capacity. The stilbene piceatannol was the major compound identified by liquid chromatography-electrospray ionization-tandem mass spectrometry (3.68 g/100 g seed dry basis). These results reinforce that agro-industrial waste demonstrates potential as a source of bioactive compounds, with implications in human health as well as in food and chemical industries.