Recovery of Brazil nut cake oil as the first step toward designing a sustainable Amazonian biorefinery

Abstract

Brazil nut oil (Bertholletia excelsa) is obtained by cold-pressing, but this method has limited yields, leaving a residual cake rich in oil (> 50 % m/m). This study investigated the extraction of this residual oil using hexane (OHx) – a traditional but toxic solvent – and bioethanol (OBe) – a renewable and unconventional alternative. The chemical composition and functional properties of the extracted oils and commercial oil obtained by cold- pressing (OPc) were determined. All the oils showed similar fatty acids and acylglycerols profiles, with a predominance of linoleic and oleic acids (> 78 % m/m), and high triacylglycerols content (> 96 % m/m). OBe presented a higher content of phytochemicals, mainly polyphenols (377.39 µg/g oil vs. 106.11–257.43 µg/g oil from OPc and OHx samples, respectively), tripling the antioxidant activity and thermo-oxidative stability (24.70 h at 110 C vs. 7.54–9.68 h from OPc and OHx samples, respectively). However, bioethanol can also extract aflatoxins, if the cake is contaminated. The oils, regardless of the extraction method, did not show anti- proliferative activity against the tumor cell lines tested, but did show preliminary cell safety in non-tumor human cell lines. Thus, bioethanol keeps the oil healthy, improves its useful life and makes it more suitable for heating applications. This strategy contributes to the sustainable development of Amazonian resources in a biorefinery concept and is aligned with the bioeconomy and the Sustainable Development Goals (SDGs).