Physicochemical Characteristics and Composition of Indian Soybean Oil Deodorizer Distillate and the Recovery of Phytosterols

The deodoriser distillate (DOD) of Indian soybean oil obtained from two industries processing soybean oil was investigated for its physicochemical characteristics, its composition of tocopherols, phytosterols, fatty acids and recovery of phytosterols for use in nutraceutical products. It was found that the two DOD samples studied were dark in color and had higher amounts of free fatty acids (22.7 and 49.9%), unsaponifiable matter (11.8 and 21.9%) (5-10 times found in soybean oil), total tocopherols (1957-2256 mg/100 g) (20 times the amount in soybean oil), and 6-10% of phytosterols (12-20 times the soybean oil). The fatty acids found were palmitic (23.2-25.5%), stearic (1.4-2.4%), oleic (23.8-26.1%), linoleic (40.4-41.1%) and linolenic (2.7-3.2%) acids. The unsaponifiable matter (21.9%) and phytosterols (8.7%) content of DOD-2 were higher than in DOD-1 and hence was more suited for isolation of phytosterols. Using hexane and water for crystallisation, the DOD-2 yielded a phytosterol fraction with lower recovery of 13.2-17.8% while treatment with alkali to remove FFA and the glycerides followed by organic solvent extraction yielded unsaponifiable matter containing phytosterols with a recovery of 74.6%. Later the unsaponifiable matter was purified by double crystallisation into a mixture of phytosterols of 87% purity containing beta-sitosterol (34.3%), stigmasterol (3.1%) and campesterol (50.1%). The product may find use in foods, pharmaceuticals, cosmetics and allied industries probably as a nutraceutical.