Fatty acid

“ Fats have in their molecules the chemical elements carbon, hydrogen, and oxygen. These elements are put together into two groups, or compounds, glycerin and fatty acids, which, when chemically united, form a fat. When fats are exposed to the open air, and thus contaminated with bacteria, they are likely to become rancid; that is, some of the glycerin and fatty acids are set free from each other. If butter is the fat so decomposed, it becomes very disagreeable, on account of the volatile butyric acid that is set free. ”

“ Vegetable and animal fats and oils are, when pure, neutral substances formed by the combination of fatty acids with glycerine. They possess the property of saponification, that is, of forming a soap when treated with an alkali, the soap being the alkaline salt of the fatty acid. Under certain conditions, the fat can be split up into free fatty acid and glycerine by the action of acids, or even water alone. ”

“ The fat is mixed with 4-6% of the acid and treated with steam in boiling water till the hydrolysis is complete, when on standing the glycerin and sulphuric acid sink to the bottom and the fatty acids rise to the top. ”

“ When fats are saponified by an alkali, stearate, palmitate, and oleate of potassa or soda, as the case may be, are produced and glycerin is set free. On decomposing either of these compounds with sulphuric acid a sulphate of the alkali is formed, and the fatty acid is precipitated. Some of the fatty acids, as stearic, cerotic, palmitic, and lauric, are solid at ordinary temperatures; others, as oleic, are liquid. The hard fatty acids are extensively used as candle materials, being superior in every respect to the natural fats from which they are derived. ”

“ In an acid fat there has been a hydrolysis of the fat and it has developed a rather high percentage of free acid. A rancid fat is one in which have been developed compounds of an odoriferous nature. An acid and rancid fat is one in which both free acid and organic compounds of the well known disagreeable odors have been produced.
It cannot be definitely stated just how this rancidity takes place, any more than just what are the chemical products causing rancidity. The only conclusion that one may draw is that the fats are first hydrolyzed or split up into glycerine and free fatty acids. ”

“ Further, the observation has been made that the fat particles in the epithelial cells are small at the beginning of intestinal digestion, but that they grow larger when the digestion has been in progress some time, as though the droplets were made at the point where they are seen. Again it has been shown that the fat ferment in the small intestine is abundantly able to convert the fat of an ordinary meal completely into fatty acid in the time usually required for a meal's digestion. ”

“ The amount of benzoic acid, 2.92 per cent., or about 1⁄7 grain per pill, is insignificant from a therapeutic standpoint, since an average dose is 0.5 gm., or 8 grains. Fatty acids, and the fatty matter from colchicum seed are inert, at least in the quantities found here. The only office which fatty acids might perform, would be to give the pills an enteric quality, preventing their absorption until they reach the intestine. The sugar of milk, about 10 per cent., or 1⁄2 grain per pill, no doubt is simply an excipient. ”

“ Recently, fatty acids have been prepared from carbohydrates, by first breaking the hexoses down into three-carbon compounds, then carefully oxidizing these to pyruvic acid, CH3·CO·COOH, which can then be condensed into acids having longer chains. The violent reagents and long-continued processes which must be employed for the artificial hydrolysis or synthesis of the fats are in sharp contrast with the easy and rapid transition [Pg 137] of carbohydrates to fats, and vice versa, which take place in both plant and animal nutrition. ”

“ With care scarcely any of the fatty acid will find its way into the filter. After the washing with water is completed and the flask drained, he washes any fatty acid that may be on the filter into the flask by means of a mixture of alcohol and ether on a water bath, and finally dries the fatty acids in the flask at a temperature of 105° C. The drying can be done readily if the melted fat is now and then shaken briskly, so as to subdivide the water as much as possible. ”

“ This action, according to ferment law, would continue till a mixture of fat and fatty acid in chemical equilibrium was produced. But in the intestine, absorption begins and fatty acid is removed as fast as formed, thus allowing the ferment to continue its action as long as any fat remains in the intestine. But if both fatty acid and ferment are absorbed together, then, as soon as they get inside the absorbing cell, the ferment in the presence of fatty acid only will begin its work over again, which then will be the formation of droplets of neutral fat from the fatty acid absorbed. ”

“ This process is called hydrogenation, so named because the process is really one of adding hydrogen until the fat becomes saturated and less likely to undergo decomposition into fatty acid and glycerin. The fats thus formed seem to be equal to the animal fats so far as digestion and utilization are concerned, and hence are of considerable economic value at the present time.
Certain fats, including those of butter and milk, are rich in the so-called vitamines, and have been shown, by recent experiments upon animals, to be efficient growth stimulants. ”

“ The production of a substance known as fat or oil, composed of oxygen, hydrogen, and carbon in the form of a fatty acid and combined with glycerine, is a function of almost every plant. The fat acids are usually in combination with glycerine, which plays the part of a base and in so far as its proportion by weight is concerned is much less important than the fatty acid itself. In round numbers it may be said that nine-tenths of all glycerids or fats are composed of a fatty acid and one-tenth of glycerine. ”

“ It has long been known that whilst recently rendered animal fats are comparatively free from acidity, freshly prepared vegetable oils invariably contain small quantities of free fatty acid, and there can be no doubt that this must be attributed to the action of enzymes contained in the seeds or fruit from which the oils are expressed, hence the necessity for separating oils and fats from adhering albuminous matters as quickly as possible. ”

“ Stearin, when thus treated, yields stearic acid, palmitin gives palmitic acid, olein gives oleic acid, and common animal fat, which is a mixture of several neutral bodies, affords, by saponification by an alkali and subsequent decomposition of the soap, a mixture of the corresponding fatty acids. These bodies are not, however, the only products of saponification; the change is always accompanied by the formation of a very peculiar sweet substance called glycerin, which remains in the mother liquor from which the acidified fat has been separated. ”

“ Very irritating fat acids are liberated by the decomposition of the fatty constituents of the food, which, with the acid products of the fermentation occurring in the starch and sugar of the diet, cause a sensation of heat and distress through the abdomen. Usually, the bowels are torpid, but in some cases the stools are relaxed, having the consistence and presenting somewhat the appearance of oatmeal porridge. They may be firm, moulded, even hard. The gas discharged and the stools are offensive, with a carrion-like odor. ”

“ Animals in running water leave a fat after three years, which is more abundant in the intestines than in the muscles, and more fat is formed in stagnant, than in running water.
Chevreul, 1812, found the fat of church yards to contain margaric and oleic acids, combined with yellow colouring and odorous matters, also lime, potash, oxide of iron, lactic acid salts and azotized matter. He supposes the fatty acids are liberated from their glycerine by ammonia, which subsequently itself escapes, and that adipocire is thus formed from the original fat of the body. ”

“ From oxide of glycyl ensues acroline; oleic acid affords a fatty acid, and among the decomposition products of fats containing stearine and margarine are found pure margaric acid, and, at the same time, some hydro-carbons are formed. When exposed quickly to a high temperature, fats are completely decomposed. (Oil gas.) In closed vessels the pure fats undergo no change, but, placed in thin layers in the air, the fats containing oleine and oline rapidly absorb oxygen under the strong evolution of heat, which will inflame porous bodies, as cotton wool. ”

“ When, for example, the flow of bile is lessened, an incomplete emulsification of the fats exists and the fatty acids which are highly acid in character cannot be efficiently dissolved or neutralized, or when the liver is diseased and for this reason the conversion of glycogen into glucose is interfered with, the utilization of the carbohydrate foods is thus impaired. ”

“ The latter method is by far the best, since the advantages derived by thus proceeding more than compensate the necessity of cleaning the still. Better colored fatty acids are obtained; less unsaponifiable matter is contained therein; there is no accumulation of impurities; the amount of neutral fat is lessened because the treatment of the tar with acid causes a cleavage of the neutral fat and the candle tar or pitch obtained is harder and better and thus more valuable. ”

“ The purer the fats are the more quickly their oxidation results. When the fats contain slimy materials, these latter can be destroyed with a little oxide of lead and water. (Preparation for the application of varnishes.) The action of nitric acid, nitrous acid, chlorine, sulphuric acid, &c., on fats is the same as that of these bodies on the fatty acids. ”

“ Digestion of Fat.—Several theories have been proposed at different times regarding the digestion and absorption of fat. Among these, what is known as the "solution theory" seems to have the greatest amount of evidence in its favor. According to this theory, the fat, under the influence of the steapsin, absorbs water and splits into two substances, recognized as glycerine and fatty acid. ”

“ On the other hand, fatty food eaten with the meals prolongs the stay of food in the stomach and causes an increase in the secretion of hydrochloric acid. An excess of the acid, as we have just learned, is favorable to the development of heartburn. Therefore, as a further precaution against this source of discomfort, it is advisable not to use a large amount of butter or of salad oil, and to refrain from fried food, rich desserts, or any other article of diet known to contain a relatively large amount of fat. ”

“ My theory of the cookery of fat is simply that heat, when continued long enough, or raised sufficiently high, effects an incipient dissociation of the fatty acids from the glycerine, and thus assists the digestive organs by presenting the base and the acids in a condition better fitted (or advanced by one stage) for the new combinations demanded by assimilation. Some physiologists have lately asserted that the fat of our food is not assimilated [159] at all—not laid down again as fat, but is used directly as fuel for the maintenance of animal heat. ”

“ When fats are to be eaten, care should be taken that they be as fresh as possible, or, if this is not feasible, they should be preserved in such a way as to prevent their becoming rancid—a condition which is the result of the formation of fatty acids, lending a peculiarly unpleasant odor and taste, and producing a decided decrease in food-value. ”

“ It may be that the glycerine of the fat we eat is assimilated like sugar, while the fatty acids act directly as fuel. This view may reconcile some of the conflicting facts (such as the existence of fat in the carnivora) that stand in the way of the theory of the uses of fat food above referred to, according to which fat is not fattening, and those who would "Bant" should eat fat freely to maintain animal heat, while very abstemious in the consumption of sugar and farinaceous food. ”

“ The fats belong to a group of substances that are strongly surface-active, while the products of disintegration produced by their decomposition, such as alcohol and fatty acids, possess no marked influence over surface-tension. If plasma of a normal animal be mixed with any kind of fat, such as tributyrin, and the mixture be allowed to flow from a capillary tube, a certain number of drops escape in a given time. But if any fat gets into the animal's circulation by whatever means, then the number of drops escaping through the capillary tube decreases. ”

“ But the change of fatty matters into fat-acid and glycerin takes place with some materials (such as palm oil) at, or below, the melting-point of bismuth, yet the heat has been carried considerably above the melting-point of lead without any apparent injury, and the decomposing action of the water becomes more powerful as the heat is increased. By starting the apparatus at a low heat, and gradually increasing it, the temperature giving products most suitable to the intended application of the fatty body employed, can easily be determined. ”

“ Animal fats, absorb comparatively less halogen than vegetable fats, and the power to combine with iodine increases with the transition from the solid to the liquid state, and attains its maximum with vegetable oils—the method being adapted to the examination of fat mixtures containing glycerides and free saturated fatty acids, provided that substances which under similar conditions combine with iodine are absent. ”