Lecithins emulsion properties

Chem. Descrip. Complexed lecithin CAS 8002-43-5 EINECS/ELINCS 232-307-2 Uses Instantizer, spray oils, mold release for foods food emulsifier for w/ 0 emulsions concrete (powder dispersant) dust control latex paints coatings/adhesives feed additives leather tanning lubricants mold release agents pesticides/herbicides corrosion/rust inhibitors putty/ caulking compds. emulsifier for w/o emulsions Properties Translucent fluid vise. 10 stokes HLB 2.0 acid no. 25 max. Beakin LV3P [ADM Lecithin]... 

Chuah, A.M., Kuroiwa, T., Kobayashi, I., Nakajima, M. (2009). Effect of chitosan on the stability and properties of modified lecithin stabilized oil-in-water monodisperse emulsion prepared by microchannel emulsification. Food Hydrocolloids, 23, 600-610. 

Dickinson, E. and Yamamoto, Y. 1996a. Viscoelastic properties of heat-set whey protein-stabilized emulsion gels with added lecithin. J. Food Sci. 61 811-816. 

Acetylated lecithins have improved fluid properties, improved water dispersibility, and are effective oil-in-water emulsifiers for a wide variety of food formulations (56, 58). Moderately and highly acetylated lecithins are resistant to heat and can be repeatedly heated and cooled without darkening. The intended uses for minimally acetylated products are in infant foods, coffee whiteners, meat sauces, and gravies, and for oil-in-water cosmetic emulsions. Moderately and maximally acetylated products are used in cheese sauces, release agents in pumpable and aerosol formulations, and shortenings. 

Hydroxylated lecithin. Hydrogen peroxide, in addition to bleaching, can also hydroxylate lecithin. Hydroxylation imparts hydrophilic properties, improves moisture retention, and contributes to the formation of stable oil-in-water emulsions. 

Emulsifying properties. One of the major functions of commercial lecithins is to emulsify fats. In an oihwater system, the phosphohpid components concentrate at the oUrwater interface. The polar, hydrophilic parts of the molecules are directed toward the aqueous phase, and the nonpolar, hydrophobic (or lipophilic) parts are directed toward the oil phase. The concentration of phospholipids at the oihwater interface lowers the surface tension and makes it possible for emulsions to form. Once the emulsion is formed, the phosphohpid molecules at the surface of the oil or water droplets act as barriers that prevent the droplets from coalescing, thus stabilizing the emulsion (159). 

The manner in which lecithin is modified to achieve increased hydrophilicity will greatly affect its emulsification properties. Different modifications will create lecithin products with different apparent HLB (hydrophile-lipophile balance) values, a term used to convey the approximate degree of water dispersibility (hydrophilicity) of lecithin products (31). The higher its HLB value, the more water dispersible the lecithin product. In o/w emulsions, the type of fat to be emulsified may require a specific type of hydrophilic lecithin for optimum emulsion stability. Dashiell (31) provides a short listing of fat types, and the corresponding class of lecithin found to give the most stable emulsion in model systems of water/fat/ emulsifier. 

The range of surfactant emulsifiers used in pharmaceutical preparations is illustrated in Table 2. Surfactants are manufactured from a variety of natural and synthetic sources and consequently they show considerable batch-to-batch variations in their homologue compositions and in trace impurities from the starting material. For example, batch variations in the number of neutral phospholipids occur in lecithin surfactants and non-ionic polyethylene surfactants show variations in the number of moles of ethylene oxide. The mechanisms by which such batch variations lead to differences in emulsifying properties are now better understood. Although synthetic and semisynthetic surfactants form by far the largest group of emulsifiers studied in the scientific literature and many of them are available commercially, their use in pharmaceutical emulsions is limited by the fact that the majority are toxic (i.e., haemolytic) and irritant to the skin and mucous... 

In many food emulsions, more than one surfactant is present, so that mixtures of proteins, small-molecule surfactants (oil soluble and water soluble), and lecithins may be present. The result of this is that the interfacial layer will contain more than one type of molecule. The properties of the emulsion (the sizes of the droplets and the functionality) will, in turn, depend on which of the molecules in the formulation is actually on the interface. 

It is apparent that real food emulsions are likely to behave in a more complex way than are simple model systems studied in the laboratory. This may be especially important when lecithins are present in the formulation. Although these molecules are indeed surfactants, they do not behave like other small-molecule emulsifiers. For example, they do not appear to displace proteins efficiently from the interface, even though the lecithins may themselves become adsorbed (123). They certainly have the capability to alter the conformation of adsorbed layers of caseins, although the way in which they do this is not fully clear it is possibly because they can fill in gaps between adsorbed protein molecules (124). In actual food emulsions, the lecithins in many cases contain impurities, and the role of these (which may also be surfactants) may confuse the way that lecithin acts (125). It is possible also for the phospholipids to interact with the protein present to form vesicles composed of protein and lecithin, independently of the oil droplets in the emulsion. The existence of such vesicles has been demonstrated (126), but their functional properties await elucidation. 

Chem. Descrip. Compd. of lecithin and coconut fatly acid, ethor lated Uses Emulsifier, wetting agent, and dispersant for aq. systems stabilizer for latex and emulsion paints, leather finishes, water isp. and -reducible air-dry and stoving all ds, offset printing inks, textile auxs. Properties Lt. bm. vise, liq. vise. 15 Pas amphoteric 99% solids Use Level 1-5%... 

Highly oxidizable oils such as fish oils can be protected by a process known as microencapsulation, which coats the oil with a matrix of protein (gelatin, casein), carbohydrates (starch, cellulose, carboxymethylcellulose or cellulose derivatives) and lecithin. Microencapsulation provides protection against oxidation and imparts oxidative stability. The use of carboxymethylcellulose and cyclodextrins as coatings is claimed to provide better protection of oils by improved oxygen barrier properties. For special applications as nutritional supplements, fish oils enriched in n-3 PUFA are microencapsulated, in the presence of antioxidants, into a powder that is relatively stable at ambient temperatures. However, encapsulated fish oils can impart undesirable fishy taste when incorporated into food emulsions. More research and development is needed to evaluate potential applications and benefits of active packaging to increase the shelf life of fish oils and other highly oxidizable oils in foods. 

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