Extraction of High Stearic High Oleic Sunflower Oil Using Eco-Friendly Solvents

Abstract

The present work aimed to evaluate the extractive performance of three green solvents—absolute ethanol, hydrated ethanol (96%), and absolute isopropanol (AIP)—in high stearic high oleic sunflower seeds, comparing them with the conventional solvent hexane. The oil yield from exhaustive Soxhlet extraction with hydrated ethanol was significantly lower, with no significant differences being observed among the other solvents. Extraction with AIP produced the extract with the lowest non-lipid material content and the oil with the lowest concentration of crystallizable waxes, showing a 53% reduction compared to hexane. Since AIP showed a higher extraction efficiency than absolute ethanol after 4 h of processing, its oil extraction kinetics when used as a solvent were further studied. A modified Fick’s diffusion model revealed that, for hexane extraction at 50 °C, the effective diffusion coefficient and the washing fraction were higher than those for AIP extraction (26% and 5.4% higher, respectively). No clear dependence of the oil extraction kinetics on the temperature was observed between the studied temperatures (50 °C and 70 °C). The results showed the feasibility of using absolute ethanol and AIP as alternatives to hexane. Additionally, isopropanol presented operational advantages, producing oil that required less dewaxing during refining than that extracted with hexane or ethanol and showing higher oil selectivity than ethanol.