Bioactive Compounds and Pectin from Residues of the Passion Fruit Processing: Extraction Using Green Technology and Characterization

Abstract

The objective of the study was to extract (using pressurized liquid extraction (PLE)) and characterize the bioactive compounds and pectin from the residue of the passion fruit processing. The extract of the passion fruit peel was obtained with ethanol (99.5%) in different temperature (80-100 oC), flow rate (0.5-1 mL/min) and pressure (50-100 bar) conditions (23 factorial design). The highest yield (32.13%) was obtained employing 50 bar, 80 oC and 0.5 mL/min. The lipid fraction of the extract was composed of palmitic acid, linoleic acid and oleic acid. From the residual pie (after the obtention of the extract), pectin extraction was carried out with water as extraction solvent, in pressurized (50-100 oC, 50-100 bar, 0.5-1 mL/min, 23 factorial design) and non-pressurized (50-100 oC, 0.5-1 mL/min, 22 factorial design) processes. With the pressurized system, the highest yield (27.67%) was obtained using 50 bar, 100 °C, and 0.5 mL/min, resulting in esterification percentage of 89.32%. With the non-pressurized system, the highest yield (20.77%) was obtained using 75 oC and 0.75 mL/min, resulting in esterification percentage of 86.54%. The pectin showed high purity, confirmed by 1H NMR analysis and absence of contaminant signals. Through gel permeation chromatography (GPC) analysis, it was possible to verify that pectin with different mean molar mass (¯Mw) and Polydispersity Index (PI) can be obtained, depending on the process parameters. The oil of the passion fruit seed was extracted under different conditions of temperature (40-80 oC), pressure (50-100 bar) and flow rate (0.5-1 mL/min) using ethanol as extraction solvent and rotating composite central design (CCRD). The best condition (50 bar, 80 oC and 0.5 mL/min) showed 25.8% yield. The concentration of piceatannol present in the oil (0.05-1.3 µg/mL) was higher than that found in commercial oil samples obtained by conventional methods (not detected). It can be concluded that the passion fruit residue can be used to obtain bioactive compounds and pectin. PLE proved to be efficient and very promising, because it is a green methodology and resulted in products with high quality (pectin with high purity and oils with higher concentration of piceatannol).