In this study, production of α-linoleic acid concentrated from crude perilla oil by gradient cooling urea inclusion was optimized. The fatty acid composition was determined after ethyl esterification by gas chromatography (GC). In this process, orthogonal experiment was carried out. Under optimum conditions, the maximum amount of α-linoleic acid (91.5%) was obtained at a urea to fatty acid ratio of 3, a solvent to fatty acids ratio of 7, a reaction temperature of 348 K and a crystallization time of 690 min. A simple method of gradient cooling urea inclusion was used to purify α-linolenic acid by using urea to form inclusion complexes with the saturated and the less unsaturated fatty acids, which enhanced the purity of α-linoleic acid ethyl ester by above 90%.
