Soya lecithin production

Table 10.4 Typical total composition in % of soya lecithin products...

Soya lecithin is a natural product which contains about 34% glycerides (soya oil), 5% sugars, and 61% phosphatides. The phosphatides in turn are comprised of phosphatidyl choline, i.e., chemical lecithin (20%), phosphatidyl ethanolamine (20%), and phosphatidyl inositol (21%). 

Contraindications History of hypersensitivity to atropine, soya lecithin, or related food products such as soybean and peanut... 

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). 

The main use of our sucroglycerides, in the past and today, remains in the animal feeding market, where we sell our product under the trade name Celynol. We sell two products Celynol MST 11, which is a tallow sucroglyceride and Celynol TL, which is a mixture of tallow sucroglyceride and soya lecithin. Both of these have been approved in the animal feeding meirket by Belgium, England, France, Italy and Switzerland. 

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. 

These products have a higher melting point, are stable against oxidation but less soluble in oils and fats. The process is preferably carried out with quite pure PC fractions. With crude lecithin the reaction is not very well controlled and the catalysts are poisoned by the impurities. Soya lecithins with hydrogenated PC 80-100% contents are commercially available. These fractions are used as polar lipid excipients in pharmaceutical products and cosmetics [15]. 

Some emulsifiers, e.g. lecithin, are purely natural products whereas others are manufactured usually from natural materials. Typical materials for manufactured emulsifiers are vegetable oils, e.g. soya bean oil or palm oil animal fats, e.g. lard or tallow and glycerol. Where required, some manufacturers can supply products with kosher or halal certificates. Other raw materials are organic acids such as fatty acids, citric acid, acetic acid and tartaric acid, in addition to sorbitol and propylene glycol. 

Release/parting properties. Lecithin functions as the active ingredient in a wide variety of food-grade release formulations. Products for institutional and retail use are available in aerosol and nonaerosol forms containing from 0.5% to about 15% lecithin (31). Common ingredients in release formulations are as follows (31) (from a Central Soya Co. market survey, 1986). 

For food uses, soya derivatives are used as ingredients in a wide range of consumer foods. Examples are soya oil, lecithin, soya flour in bakery products, soya protein isolates, etc. This chapter will not deal with these ingredients, but rather focus on food products made by fermentation processes. 

Other somewhat less-rich sources of lecithin are cottonseed, rapeseed and sunflower oils, but palm oil contains very little (Figure 12.31). Soya beans account for over half the world production of all oilseeds and vegetable oils. The United States is the largest soya producer ( 60%) and Brazil the second ( 20%) (Tables 12.44 and 12.45). 

The lecithins are white waxy substances, rapidly turning yellow or brown on exposure to air very hy oscopic, and form colloidal solutions very easily with HgO readily hyd. by acids, alkalis and enzymes form cryst. addn. products with many inorganic salts, particularly C iCla- The lecithins from egg yolk and soya bean are the best kno vn. 

Saturated lecithins and the three types of aldehydic cores obtained by reductive ozonolysis of unsaturated lecithins can be separated through reversed phase partition chromatography [168]. Fig. 147 shows photo-densitometric curves from thin-layer chromatograms of fission products derived from the lecithins of egg, bovine spinal cord, soya bean and wheat germ. 

Lecithin. Lecithin plays a significant role as a surface-active agent in the production of emulsions. Raw lecithin , especially that of soya and that isolated from egg yolk, is available for use on a commercial scale. Raw lecithins are complex mixtures of lipids with phosphatidyl cholines, ethanolamines and inositols as main components (Table 3.19). 

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