Advances in extracting fatty oils using unconventional solvents

Abstract

Goal. To analyze the current state of issues related to the use of solvents, alternative to petroleum, for the extraction of vegetable oils, to isolate and analyze the data on ethanol extraction in the context of processing of oil raw materials, as well as to determine the prospects for further research and implementation of the technology of extracting sunflower oil with ethyl alcohol. Methods. Retrospective bibliographic analysis, quantitative analysis of search results based on Scopus database statistics, trend analysis of the number of publications during the study period, content analysis of scientific publications, method of logical structural analysis, synthesis, and thematic generalization of data were used. Results. A new trend was identified in the extraction of oils by liquids under significant overpressure (PL-extraction, PLE). This me­thod could provide an 85–94% yield of oil, which was comparable to the effect of ultrasound. In addition, this method contributed to a higher concentration of phenolic compounds. However, the oxidation resistance of the oil was lower than that of hexane extraction. The economic efficiency of PLE was estimated as quite high (ROI return on investment — 133.5%). Ethanol showed a high extractive ability against tocopherols and phospholipids, but significantly reduced the content of waxes. In addition, it effectively removed su­gars, extracting more than 75% of their original amount. Effective diffusion coefficients (De) of the oil were 9.94 × 10–10 m2/s at 50°C and 3.11 × 10–9 m2/s at 60°C. Diffusion of sugars (6.50 × 10–10 m2/s for 50°C, 1.51 × 10–9 m2/s for 60C) indicated a significant thermal dependence of the process. Conclusions. One of the most environmentally friendly and safe extractants is ethyl alcohol. Of considerable interest to researchers is extraction under high-pressure conditions as an alternative to the method using substances in a supercri­tical state. It is worth noting the variety of oil raw materials used in studies using alternative extractants.