Glycerol Fatty Acid Esters are used as emulsifiers or oiling agents for
foods, spin finishes and textiles; antifoaming and antistatic agents for
plastics; and lubricants, water treatment, metal working fluids, and
dispersing agents. End applications include cosmetics, foods, personal care
products, medicine , pesticides, paper making, plastics and paints.
An emulsion is a mixture of two repel substances (water and oil).It
induces a dispersion of undissolved material throughout a liquid.
The dispersed phase is dispersed in the other continuous phase. Emulsions are unstable and thus tend to revert to the stable state of oil
separated from water spontaneously. Physical energy such as shaking, stirring, homogenizers, or spray processes is
needed to keep an
emulsion. Surfactants increase the kinetic stability of
emulsions and make the emulsion does not change
significantly for long term. An emulsifier is a type of
surfactant used to keep emulsion stable and well
dispersed. Emulsifiers typically have a hydrophobic head and a
hydrophilic tail in one molecule. The emulsifiers will surround an hydrophobic molecule and hydrophilic tail
form a protective layer so that the oil molecules
cannot "clump" together. This action helps keeps phase well
dispersed. Some of the
most important emulsifiers include salts or esters of higher fatty acids, fatty alcohols,
esters of monoglycerides, gelatin, lecithins, polysaccharides and casein.
Glycerides
(also known as acylglycerols) are esterified to glycerol
with fatty acids. Glycerol haing three hydroxyl functional groups
is esterified with one, two or three fatty acids to form monoglycerides, diglycerides and triglycerides
respectively. A monolyceride is a compound consisting of one fatty acid chains covalently
bonded to a glycerol molecule
through ester linkage. Diglyceride and triglyceride consists of two and three
fatty acid chains respectively. Examples of triglyceride include
triacetin, trimyristin, and triolein. Monoglyceride usually
occurs as an intermediate in triglyceride metabolism by means of a release of a fatty acid from lipase. The commercial source may be either animal or vegetable
fats, and synthetically produced as well. Mono- and diglycerides
are common food
additives used as an emulsifier or stabilizer to blend together certain ingredients
of oil-hating and
water-hating, which would not otherwise blend well.
Glycerine
(glycerin, glycerol, or 1,2,3-propanetriol) is the simplest trihedric alcohol.
Pure glycerine, with a specific gravity of 1.26, is a colorless, odorless,
sweet, viscous liquid melting at 17.8 C boiling at 290 C. It decomposes at
boiling point and produce corrosive fumes of acrolein. It is miscible in water
and forms a solution in any proportion. It is also soluble alcohol but only
partially soluble in common organic solvents such as ether and ethyl acetate. It
resists freezing. It is hygroscopic, which favors as a humectant to retain
moisture in cosmetics. It reacts violently with acetic anhydrides in the
presence of a catalyst. It is obtained as a byproduct when fats and oils are
hydrolyzed to yield fatty acids or soaps. Glycerol is also commercially
synthesized from propylene (Dow Chemical). Glycerol can also be obtained based
on a proprietary fermentation processing. Glycerol is widely used; as a solvent,
food additive, sweetening agent and emollient and emulcent with magnesium
sulphate used in the treatment of septic wounds and boils; in the manufacture of
alkyd resin, cellophane, ester gums, plasticizer, dynamite, nitroglycerine,
cosmetics, liquid soap, perfume and toothpaste (good solubility and taste give
glycerine an edge on sorbitol in toothpastes, which are estimated to make up
almost one-third of glycerine's market in personal care products); as a
component of antifreeze mixtures; to keep fabrics pliable, to preserve printing
on cotton, to keep frost from windshields; as a source of nutrients for
fermentation cultures in the production of antibiotics; as a preservative in
some pharmaceutical and biological preparations and in non-alcoholic extracts
and tinctures. It has many other applications.