Sequential green extractions based on supercritical carbon dioxide and pressurized ethanol for the recovery of lipids and phenolics from Pachira aquatica seeds

Abstract

Pachira aquatica Aubl. (munguba) seeds represent a rich source of lipids and biocompounds with potential for sustainable exploitation. This work evaluated the feasibility of using supercritical fluid extraction (SFE) and pressurized liquid extraction (PLE) to obtain a lipid-rich fraction and extracts rich in biocompounds from munguba seeds. The SFE at 30 MPa/60 °C/120 min was the best condition for munguba seed oil (MSO) extraction (52 g 100 g−1), providing 95% extraction efficiency compared to Soxhlet with n-hexane. The MSO was composed mainly of palmitic (76.93%), oleic (9.66%), and linoleic (8.15%) fatty acids. Differential Scanning Calorimetry (DSC) showed that the SFE affects the crystallization and melting patterns of MSO, which presents a solid-state below 35 °C, regardless of the extraction conditions used. Thermogravimetric analysis showed high thermal stability for MSO (up to 249 °C), associated with palmitic acid’s high content. Scanning Electron Microscopy (SEM) showed wrinkled, globular, and irregular structures on the defatted munguba seed cake from SFE. These morphological conditions helped obtain PLE-extracts with a significant content of total phenolic compounds ranging from 53.66 to 350.29 mg GAE 100 g−1. The extracts also presented in vitro antioxidant activity measured by chemical (ferric reducing antioxidant power - FRAP of 2.04–28.41 mM Fe2+ 100 g−1; inhibition of DPPH between 8.45 and 61.58%), and biological-based (inhibition of lipid peroxidation from 25.47 to 49.45%) methods. This sequential process based on non-toxic solvents is a high yield alternative to recover the rich oil and the phenolic fractions from munguba seeds.