Co-products from oil refining

Soybean is the predominant source of lecithin for pharmaceutical and food purposes because of its availability and outstanding functionality. The composition of crude soy lecithin is shown in Table 2.10. It contains a large amount of neutral oil, and crude lecithin is usually deoiled to improve its functionality. This separation is based on the solubility difference of neutral and polar lipids in acetone. Phospholipids are precipitated from solution and separated. 

Crude Degummed Magnesol Silica Deodorized Crude Degummed Neutralized Bleached Deodorized 

Alcohol fractionation of deoiled lecithin provides alcohol-soluble and alcohol-insoluble fractions enriched with PC and PI respectively. The PC-enriched fraction is an excellent oil-in-water emulsifier. The Pi-enriched fraction is a good water-in-oil emulsifier often used in the chocolate industry to increase the viscosity of the mass, therefore reducing the need for cocoa butter. The typical composition of these lecithin products is shown in Table 2.11. 

Supercritical CO2 extraction has been used to extract PC from deoiled soybean lecithin selectively (Teberikler el al. 2001). The effects of temperature, pressure and amount of ethanol on PC extraction were examined and optimum conditions described to yield a high-purity product. Soybean lecithins can be chemically altered to modify their emulsifying properties and to improve their dispersibility in aqueous systems. Phospholipids may be hydrolyzed by acid base or enzyme (phospholipase A) to achieve better hydrophilic and emulsification properties. Hydroxylation of lecithin improves its oil-in-water emulsification property and water dispersibility. Acetylation (of PE) creates improved fluid, emulsification, and water dispersion (List 1989). 

Lecithin recovered from solvent extracted and mechanically pressed soybean oils has different phospholipid class composition (Wu and Wang 2001). 

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