Free fatty acids , definition

Nor are those in phase 2 free of 5.8- to 5.9-micron absorbing material. The latter peak is characteristic of both free fatty acid and phase 1 acid-soap. Hence, this does not allow a definitive statement of the second species present. It is, however, likely to be phase 1 (or 3) material since the DTA results point to the absence of free fatty acid in most cases. Furthermore, acid-soap in one phase can transform to another phase as has been clearly demonstrated. 

Free fatty acid (FFA) analysis definition of FFA, 471 lipid composition, 471 -472, 476-477 Free induction decay (FID), 22 (fig.), 23 Free radicals lipid oxidation, 535-536 lipids, 525... 

It has been criticized that the effect of acyl-CoA is unspecific and due to a general detergent action. However, acyl-CoA does not induce permeability in parallel with Cl permeability [85], and there are clearly effects of palmitoyl-CoA on brown fat mitochondria at concentrations below those that yield (definitely unspecific ) uncoupling in rat liver mitochondria. Further, the uncoupling effects of free fatty acids are clearly — at low concentrations — better if acyl-CoA formation is allowed to proceed than when it is hampered [81] (Fig. 10.14). 

Vesely and Jakes (13) pointed out that the definition for lipides adopted in 1923 was not sufficiently precise. It included, among lipides, the fats formed of mixtures of esters and nonlipidic substances (free fatty acids, steroids, carotenoids, hydrocarbons) on the other hand, certain essential oils formed mainly of esters might be considered lipides. Vesely and Jakes advocated a more precise and concise definition for lipides natural esters nonvolatile with steam and possessing no aromatic ring in their molecule. ... 

By definition, a fatty acid is a carboxylic acid that contains twelve or more carbons terminating in a carboxyl group. Because carboxyl groups disassociate at pH above 4-5, free fatty acids occur as negative carboxylate anions (R—COO ) in seawater and marine sediments. Although fatty acid salts are more water-soluble than hydrocarbons. 

The factors which lead to the formation of emulsions are not definitely known. The most permanent emulsions are formed when an insoluble oil is shaken with a solution which contains a substance that interacts with one of the constituents of the oil to produce a colloid. This occurs when an oil containing free fatty acids is shaken with an aqueous solution of an alkali. A layer of soap is formed around the particles of the oil, and it is probable that a layer of oil may surround the colloidal partides of soap. When a solution of egg albumin is shaken with olive oil, a layer of the coagulated protein is formed around the drops of the oil and emulsification takes place. 

Saponification value is a measure of the molecular weights of the triacylglycerides in coconut oils. The triacylglycerides with high value of saponification value are considered to make better quality soaps than those with low saponification value. As definition, saponification value is the number of milligrams of potassium hydroxide required to saponify completely the fatty material present and also to neutralize the free fatty acids present in one gram of the coconut oil. 

There are two forms of the hydrolytic enzyme, one of which is specific for short chain esters like retinyl acetate, even though this ester does not occur naturally The other has maximum activity with retinyl palmitate as substrate but also hydrolyses other long chain esters. As in the hydrolysis of cholesteryl esters, the enzyme is not just a non-specific esterase, but has quite definite specificity for retinyl esters. In vitamin A deficiency, the activity of the enzyme increases one hundred fold. The esterification enzyme resembles the low energy cholesteryl esterase in that neither ATP nor coenzyme A appear to take part in the reaction nor are free fatty acids or acyl-CoA thiolesters incorporated into retinyl esters. One of the major problems in this area of research is to identify the acyl donor, which may be, as in plasma cholesteryl ester biosynthesis, a phospholipid. 

Alkyd resins have been defined as the reaction product of a polybasic acid and a polyhydric alcohol. This definition Includes polyester resins of which alkyds are a particular type. The specific definition that has gained wide acceptance is that alkyds are polyesters modified with monobasic fatty acids. In recent years, the term nonoil or oil-free alkyd has come into use to describe polyesters formed by the reaction of polybasic acids with polyhydric alcohols in non-stoichlometric amounts. These products are best described as functional saturated polyesters containing unreacted OH and/or COOH groups, and they are finding rapidly increasing uses in organic coatings. 

E with the free radical appearing in the initial stage of the rancidity process. Further, it is possible that the hematin compounds released in the hemorrhagic phase of the exudation process accelerate the tendency of the polyunsaturated fatty acids to poroxidize (cf. Tappel, 1955). The data on hand are not sufficient, however, to exclude definitively a possible role of autoxida-tion products which arc detectable only by more sensitive methods. 

The most striking example of this is plasma fatty acids, which endogenously occur in plasma in concentrations around 200 yg/ml. In comparison, the levels of several prostaglandin metabolites are around 50 pg/ml or less. Although crossreaction with straight chain fatty acids is always very low in prostaglandin or thromboxane assays, the high amounts present in the plasma would definitely interfere in the radioimmunoassay, if the fatty acids occurred free in the sample (28). Thus, unless the samples are not extensively purified after extraction to remove the fatty acids, a simple extraction procedure cannot be recommended. The possible influence of fatty acids in radioimmunoassay has recently been pointed out (29). 

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