Screening and Characterization of 1,8-Cineole-Based\nSolvents as an Alternative to Hexane for Obtaining Nonpolar Compounds\nfrom Plant-Based Milk Coproducts

The design of new\nhydrophobic solvents is essential for replacing\nthe toxic hexane for extracting nonpolar compounds such as fatty acids.\nOn the other hand, the full use of plant matrices seeking to obtain\nnew food and pharmaceutical products from their coproducts has also\nbeen the focus of sustainable processes. This study proposed new solvents\nfor replacing hexane to extract fatty acids and hydrophobic bioactive\ncompounds from coproducts obtained from almond- and peanut-based milk\nprocessing. The COSMO-RS method was used to select terpene-based mixtures\nto substitute hexane. Experimentally, four liquid solvents were formed\nfrom 1:2 tetradecanol/1,8-cineole (TE/EU), 1:2 camphor/1,8-cineole\n(CA/EU), 1:1 oleic acid/1,8-cineole (OL/EU), and 1:1 menthol/1,8-cineole\n(ME/EU). DSC analyses indicated the reduction of the CA/EU, OL/EU,\nand ME/EU melting points concerning their components. However, the\nmelting point values predicted by the COSMO for obtaining eutectic\nmixtures differed. CA/EU was the only mixture with a melting point\nlower than the COSMO-RS-predicted\none. In contrast, the FTIR spectra did not provide a clear visualization\nof the hydrogen bond formation between camphor and 1,8-cineole. This\ncould be due to the formation of weak hydrogen bonds, a phenomenon\nobserved in other studies. Nevertheless, these solvents have the advantage\nof low viscosity, a promising feature that likely facilitated mass\ntransfer in the extraction of hydrophobic compounds from almond and\npeanut coproducts. ME/EU provided the same global extraction yield\nas hexane and higher phytosterol extraction from almond coproducts.\nOn the other hand, CA/EU provided the same global yield and squalene\ncontent as hexane from peanut coproducts. The extracts can be directly\nused in food and pharmaceutical applications since the solvents are\nusually part of the formulations. However, DSC and TGA-DTA analyses\nindicated possible ways to separate the solvents.