Effective Extraction of Tocopherols from Soybean Oil Deodorizer Distillate Methyl Esters Using Phenolic Deep Eutectic Solvents

Abstract

Tocopherols have anti-oxidation, anti-aging, prevent cardiovascular diseases and other physiological functions. Nature tocopherols are mainly produced from vegetable oil deodorized distillates. In this work, a green, rapid and mild (room temperature) solvent extraction method based on deep eutectic solvent (DES) has been developed to simultaneously extract three isomers of tocopherols (α-, γ-, δ-tocopherol) from soybean oil deodorizer distillate methyl esters (SODD-ME) for the first time. 12 kinds of tetrabutyl ammonium chloride-based DESs (TBAC-DESs) were prepared. The effect of factors on the extraction efficiency of three individuals and total tocopherols was investigated. The optimal extraction conditions were determined as follows: DES composed of TBAC and 4-methylphenol (molar ratio of 1:1), dosage of DES 6 (DES/SODD-ME, w/w), amount of hexane 1 (hexane/SODD-ME, w/w) and vortex-assisted extraction of 1 min at room temperature. Under these conditions, the maximum extraction efficiency of α-, γ- δ- and total tocopherols were 85.0%, 99.1%, 98.0% and 97.5%, respectively. The underlying extraction mechanism was that the TBAC-phenol DESs combined the three tocopherols by both hydrogen bonding and π-π interaction. Moreover, the molecular structure of the phenolic DESs had significant effect on the extraction selectivity on α-, γ- and δ- tocopherol from SODD-ME.

Keywords: Deep Eutectic Solvents, tocopherols, soybean oil deodorizer distillate methyl esters, extraction selectivity