Technology for obtaining mixed omega 3 and omega 6 fatty acids from soybean deodorizer distillate

Abstract

Deodorizer distillate, the major by-product of soybean oil refining process, rich in fatty acids, tocopherols (vitamin E), and phytosterols, is a useful material for obtaining ω-3 and ω-6 fatty acids. For obtaning the polyunsaturated fatty acids, deodorizer distillate is dehydrated by Na₂SO₄ and then free fatty acids are converted to ethyl esters. The reaction was carried out at  70 °C for 80 minutes with etanol:deodorizer distillate ratio of 20 : 1 (mol/mol) and concentrated H₂SO₄  as catalyst. Ethanol from the ethyl esterification  reaction mixture was evaporated and residual acid was removed by washing with water. Ethyl esters of fatty acids were obtained by vacuum distillation at 5 mbar and 198 - 225 °C and then hydrolysed by 2N NaOH to release free fatty acids. Polyunsaturated fatty acids were further enriched with urea to form inclusion complexes between urea and the saturated and the less unsaturated fatty acids. The ratio of urea:fatty acids was 2.4 : 1 and the ratio of ethanol (85%):fatty acids was 8 : 1. The total content of ω-3 and ω-6 fatty acids in the obtained product was 94.56%.