Separation and purification of squalene from soybean oil deodorizer distillate

Depending on conditions in the refining process, soybean oil deodorizer distillate (SODD) in Taiwan typically contains about 45% free fatty acids (FFAs) and 20% triacylglycerols (TAGs). Bioactive compounds such as tocopherols, free phytosterols, fatty acid steryl esters (FASEs) and squalene also make up a significant portion of SODD. In the present work, a modified soxhlet extraction and silica gel column chromatography were employed to isolate and purify squalene from SODD. The goal of this work was to obtain a quantitative analysis of the separation processes and to assess the feasibility of this method to isolate the constituent compounds. Here, a modified soxhlet extraction was employed for the efficient separation of FASEs and squalene into one fraction, and tocopherols, free phytosterols, TAGs and FFAs into another fraction. Starting with SODD that contains 3.91% FASEs, 1.83% squalene, 6.40% tocopherols and 5.36% free phytosterols, it was possible to obtain the first fraction enriched with FASEs (12.19%, recovery 94.32%) and squalene (6.29%, recovery 100%). The contents of FFAs, TAGs, tocopherols and free phytosterols remaining in the second fraction were 35.05%, 3.49%, 2.39% and 0.41%, respectively. The corresponding recoveries of FFAs, TAGs, tocopherols and free phytosterols in this fraction were 20.41%, 5.89%, 9.83% and 2.09%, respectively. The first fraction was subsequently introduced into a silica gel column chromatography to isolate squalene. Squalene (95.90% purity and 93.09% recovery) was obtained in the second fraction after eluting the column using 10.96 L hexane at 23 °C. Although modified soxhlet extraction requires large amount of organic solvents that are flammable and environmentally unfriendly, the solvents can be recovered easily and it requires less sophisticated equipment than molecular distillation, operates under atmospheric pressure and lower temperature.