Chemical, thermal and rheological properties and stability of sapucaia (Lecythis pisonis) nut oils

Abstract

Sapucaia (Lecythis pisonis) is a tree that grows in Colombia, Venezuela and the Guyanas and is widely distributed in Brazil. This work presents a study of sapucaia nut oils (SO) that were obtained by Bligh and Dyer (LP1) and Soxhlet (LP2) methods and were evaluated for their fatty acid composition, rheological and thermal properties, total phenolic compounds (TPC), antioxidant properties and oxidative stability using Rancimat and ATR-FTIR spectroscopy. The analyses showed that the method of extraction impacts the fatty acid profiles of SO. Oil extracts present considerable TPC content and antioxidant properties. Thermal analysis revealed three degradation steps for SO in the air atmosphere, starting at around 130 °C, being thermally stable up to 300 °C (with a ~ 5% mass loss) and reaching total degradation near 620 °C. Thermal analysis under N2 produced two degradation steps, initiating at around 130 °C and finishing at 500 °C. Rancimat also confirmed the high thermal stability of SO, with induction periods of 13.28 h (LP1) and 7.18 h (LP2). The DSC parameters of SO were similar among each other. Crystallization (− 8.04 to − 73.93 °C) and melting (− 31.34 to 8.28 °C) phases occurred over a large temperature range. SO presented FTIR spectral features with characteristic bands for vegetable oils. Ostwald–de Waele and Herschel–Bulkley rheological models indicated major pseudoplastic behavior for SO, with a predominant viscous component. These results reinforce that SO are appropriate for human consumption and open up new possibilities for their industrial exploitation, such as for food and the cosmetic, pharmaceutical and biodiesel industries.