Phospholipids soya lecithin products

Cmde oils generally contain phospholipids that are removed during the degum-ming stage of refining as a crude mixture (lecithin). This valuable product is the basis of the phospholipid industry, and phospholipids are used extensively in food products, in animal feeds, and in industrial processes. The major members are phosphatidylcholines, phosphatidylethanolamines, and phosphatidylinositols and are accompanied by smaller proportions of other phospholipids. Soybean oil (3.2%), rapeseed oil (2.5%), and sunflower seed oil (1.5%) contain the proportions of total phospholipids indicated in parentheses and are the main sources of commercial lecithins, especially soya lecithin. Palm oil contains little or no phospholipids (7-9). 

Phospholipids and other lipids are found in most natural oils. Only soya bean products (and to an extent cottonseed and sunflower oils) contain sufficient quantities (as lecithin) to be important practical sources of phospholipids (see above). 

Glycerophospholipids are important components of biological membranes and are thus widely spread in nature. Partially purified products are used for a variety of applications, with soya lecithin as a typical example. Enzymes can be used to modify glycerophospholipids in various ways and in the surfactant area removal of one of the fatty acids to make lysophospholipids is the most important example. Sometimes this reaction is carried out only to make it easier to remove the phospholipids fraction from the neutral fat, such as in the processing of vegetable oils. This enzymatic de-gumming is an important industrial process [20]. In other applications, lysophospholipids are produced in order to improve the emulsifying properties of the lipids. One such example is in the preparation of mayonnaise, with improved emulsion stability [21]. In this application, phospholipase A2 is used selectively to remove the fatty acid in the sn-2 position. 

Acid value (AV). The acid value (AV) expresses the acidity in mg KOH/g of sample. The AV represents the acidity contributed by phospholipids (in soya lecithin often 18-24 mg KOH/g) and free fatty acids. Usually the free fatty acid content of crude oil is low, so that high AV in liquid lecithins is mostly caused by the addition of distilled free fatty acids for product viscosity reasons. Hydrolysed lecithin will contain free fatty acids from the hydrolysis process. Lecithin exhibits a neutral pH value in aqueous media. To assay for free fatty acids, the correct method is to titrate only the acetone-soluble portion, whereby any contribution from the phospholipids in the AI portion is eliminated. 

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