TECHNOLOGICAL ASPECTS OF LANOLIN* By WM. M2LMST:OM N. Z. ]•Ialmstrom Company, Brooklyn, N.Y. LANOLIN IS refined wool grease which is a by-product of the wool-scouring industry. Three methods are in use for recovering wool grease from the raw wool. In the solvent extraction method the grease is leeched out by percolating a suitable solvent through the raw wool. The other two methods have this in common, that the wool is first scoured with soap and alkali. The scouring liquor containing the wool grease is then treated in either of two ways: (1) it is passed through centrifuges pro:tucing the grease known as centrifugal grease, or (2) the scouring liquor is "acid- cracked." The grease which is pressed and collected is known as degras. The solvent-extracted wool grease is dark in color, has a free fatty acid content of 7-11 per cent, and has a good physical body. Solvent wool grease is the purest form of crude material available. Very little sol- vent wool grease is used in the pro- duction of lanolin. The cenerifugal wool grease is light in color, has a free fatty acid * Presented at the May 19, 1948, Meeting of The Society of Cosmetic Chemists in New York City. content of 1-2 per cent, and has a soft physical body. In the recovery process the heavier wool grease fractions are thrown out by cen- trifugalsforce and the softer bodies are recovered. Most of the lanolin produced is manufactured from centrifuga[ wool grease. The acid-cracked wool grease or degras is dark in color, has a free fatty acid content of 12-18 per cent, and the physical body is de- pendent on the original soap used to scour the wool. The fatty acid liberated from the scouring soap is collected with the wool grease and remains mixed with the grease. A fair amount of degras is used in lanolin production. Pure wool grease is excreted by the sheep from the sebaceous glands through its hair follicles adhering to the wool fiber to protect it from the elements, (1), soil conditi•)ns, and its own waste. Hence, wool grease has excellent adhesive properties and for that reason lanolin is used in protective oils, ointments, and cosmetics to provide the necessary adhesion for assimilation, emol- liency or protection. Wool grease must be purified, alkali-refined, bleached, and de- 241
242 JOURNAL OF THE SOCIETY odorized to conform to the require- ments for lanolin in the U.S. Pharmacopceia (2). One of the synonyms for lanolin is wool fat (2). Chemically, lanolin is not a fat but a wax. Approxi- mately 7 per cent of fanolin is free alcohols and the balance is essen- tially esters of high molecular weight sterols, combined with straight chain fatty acids. There are no glycerides present. In the crude form wool grease contains free fatty acids which are reduced to 0.56 per cent maximum to meet the U.S.P. re- quirements for fanolin. The literature has many refer- ences to lanolin and its component parts. No conclusions were found to ,indicate what individual esters exist in fanolin. The esters of lanolin may be a combination of any one alcohol with any number of the fatty acids present or, conversely, any one acid may be combined with any number of the alcohols present. As there is a possibility for a tre- mendous number of combinations, we may have a long wait for any definite knowledge of the chemical entities present. However, it is possible to split the ester by com- plete saponification and to study the individual acid and alcohol frac- tions liberated. The most complete study of the acid fraction is that of Weitka•p (3). He reports that the acidic constituents of lanolin are divided into four groups. The first group is of the even normal series consisting of the acids from C•0 to C26. The second group consists ,of two even OF COSMETIC CHEMISTS acids in the alpha hydrox 7 series. The third group consists of 10 even acids from C•0 to C2• in the iso- series. The fourth group consists of 11 odd acids from Cg to C27 and Ca• in what Weitkamp calls the anteiso series. The individual acids are present in very small pYrcentages and the maximum content of any one acid is 7 per cent. Weitkamp found that the fatty acids are saturated. Lanolin has an iodine value of 18-36 showing some un- saturation, but this is present in the alcohol group. For a product to turn rancid there must be some unsaturation in the fatty acid molecule (4) for oxidation to take place at the un- saturated carbon-to-carbon linkage. As there is no unsaturation in the fatty acids of lanolin, pure lanolin will not turn rancid. Some lanolins may develop a rancid odor which is often traced to small amounts of added scouring soap which may not have been removed in alkali re- fining. The rancidity develops in the unsaturated fatty acids of the contaminating soap. Other odors may be present in lanolin due to the chemicals used as well as to dif- ferences in refining techniques. No comparable study of the alcohol fraction has been made. More work has been done on the alcohol fraction but' the results ob- tained are not as definite as those of Weitkamp in his study of the acid fraction. The early literature (5) states that the unsaponifiable part of wool grease or the wool grease alcohols consist of cholesterol, "Iso-
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