Dry and Aqueous 2-Methyloxolane as Green Solvents for Simultaneous Production of Soybean Oil and Defatted Meal

Abstract

Edible oils are currently largely obtained by solvent extraction using hexane. Despite the fact that this petroleum solvent is known to be neurotoxic, hexane extraction remains the accepted standard process for seed oil extraction and particularly, but not exclusively, for soybean oil extraction. This study evaluates an alternative replacement of hexane with a bio-based and safe solvent, 2-methyloxolane (2-MeOx), either in its dry or in its watersaturated (4.5%w) aqueous form, referred to as 2-MeOx 95.5% in this paper. The analyses focused on extraction yields, composition, and quality of the extraction products. This study also evaluates the feasibility to substitute hexane in industrial extraction processes. Therefore, a kinetic study and multistage cross-current extractions were performed. The work concluded that both 2-MeOx and 2-MeOx 95.5% are good candidates to replace hexane in industrial processes for the extraction of soybean oil, as they gave similar compositions for oil and defatted meal. Hexane and 2-MeOx also gave similar results in terms of extraction rate and performances. 2-MeOx 95.5% exhibited a slightly different behavior during extraction, which was attributed to water diffusion from the solvent to the solid matrix due to its high water activity.

Bio-Refinery of Oilseeds: Oil Extraction, Secondary Metabolites Separation towards Protein Meal Valorisation—A Review

“…Simple phenolics or polyphenols display a positive impact on health due to their anti-microbial, anti-mutagenic, anti-inflammatory, anti-carcinogenic, anticardiovascular disease, atherogenic, and antioxidant effects. Many PC are a part of the human diet, as they are present in fruits, legumes, oilseeds and beverages [39,54,93,94,96]. In general, phenolic compounds are very valuable antioxidants.…”

“…Isoflavones (substituted derivatives of isoflavone) are similar to oestrogenic hormones, capable of activating oestrogen receptors [95]. These compounds present beneficial effects on humans (menopausal women specifically), such as preventing colon, prostate and breast cancers, but also a disruptive anti-oestrogenic property on humans and animals [94]. Isoflavones appear to have a negative effect on fertility and reproduction [95], which was demonstrated in a meta-analysis published in 2009 by L. Hooper [97].…”

“…A slightly better performance for 2-MeTHF on a laboratory scale was published by the same author [119] later that year, with a yield of 47.19 g/100 g and 46.7 for hexane. Recently, Claux et al [94] investigated the use of 2-MeTHF as an alternative for the extraction of soybean oil from ground soybean seeds. To avoid a distillation step for the purification of the solvent after oil separation, aqueous 2-MeTHF (at saturation water content of 4.5%w at 55 • C) obtained after condensation and decantation of the water-2-MeTHF mixture (forming a 10.6%w water azeotrope at 71 • C), was also studied.…”

“…The price of 2-MeTHF remains the main drawback for its use in industry. While hexane's price is around 1 EUR/kg or less, the price of a kilogram of 2-MeTHF remains as high as EUR 7-9 [10,94]. The second economical drawback is the higher energy consumption for the separation of the solvent from the miscella and desolventization of the marc, caused by the higher enthalpy of vaporization and boiling point of 2-MeTHF.…”

“…The second economical drawback is the higher energy consumption for the separation of the solvent from the miscella and desolventization of the marc, caused by the higher enthalpy of vaporization and boiling point of 2-MeTHF. Additionally, a supplementary separation step is required, as 2-MeTHF forms an azeotrope with water [94]. However, 2-MeTHF presents a higher yield than the conventional hexane extraction, and, with further recycling optimization and loss reduction, the estimated global cost of the process is increased by only 0.47 EUR/ton in the case of rapeseed.…”