Free fatty acid solubility

Commercial cmde lecithin is a brown to light yeUow fatty substance with a Hquid to plastic consistency. Its density is 0.97 g/mL (Uquid) and 0.5 g/mL (granule). The color is dependent on its origin, process conditions, and whether it is unbleached, bleached, or filtered. Its consistency is deterrnined chiefly by its oil, free fatty acid, and moisture content. Properly refined lecithin has practically no odor and has a bland taste. It is soluble in aflphatic and aromatic hydrocarbons, including the halogenated hydrocarbons however, it is only partially soluble in aflphatic alcohols (Table 5). Pure phosphatidylcholine is soluble in ethanol. 

The substrate for the reaetion is triaeylglyeerol of polyunsaturated fatty acid, which is not soluble in water, but can be solubilized with high concentration in octane. The lipase converts its substrate at the interface between octane and the aqueous phase. The free fatty acid produced is poorly water soluble. 

Experiments with monkeys given intramuscular injections of a mineral oil emulsion with [l-14C] -hexa-decane tracer provide data illustrating that absorbed C-16 hydrocarbon (a major component of liquid petrolatum) is slowly metabolized to various classes of lipids (Bollinger 1970). Two days after injection, substantial portions of the radioactivity recovered in liver (30%), fat (42%), kidney (74%), spleen (81%), and ovary (90%) were unmetabolized -hexadecane. The remainder of the radioactivity was found as phospholipids, free fatty acids, triglycerides, and sterol esters. Essentially no radioactivity was found in the water-soluble or residue fractions. One or three months after injection, radioactivity still was detected only in the fat-soluble fractions of the various organs, but 80-98% of the detected radioactivity was found in non-hydrocarbon lipids. 

Sample preparation was carried out with various solvents, depending on the solubility of the sample sometimes gentle warming was necessary. Whereas mostly tetrahydrofuran (THF) in addition to methanol, ethanol and water were used for polar substances, cyclohexane and toluene proved suitable for nonpolar waxes and free fatty acids. 

Abstract The biological effects of fullerenes and, in particular, of C60 have been recognized since long time. One of the problems which hindered the application of fullerenes in medicinal chemistry regards their insolubility in water and water-based fluids. In the present chapter it is reported that C60 and C70 fullerenes are soluble in vegetable oils, in general, in esters of fatty acids and in free fatty acids. These results pave the way in the utilization of vegetable oils as vehicles in the delivery of fullerenes for both topical applications and internal use (e.g., intramuscular injection). 

Based on these considerations, it appears that the best calculation approach for the prediction of the solubility of fullerenes in free fatty acids and in fatty acids derivatives is granted by equation (13.18), but simply because we are reasoning a posteriori. It is evident from our calculations that the surprising solubility of fullerenes in free fatty acids and glyceryl esters of fatty acids, or which is the same in vegetable oils, was not easily predictable and expected on the basis of theoretical considerations. Only the intuition of Braun et al. (2007) (see also Cataldo and Braun, 2007) has led to this important discovery, which may have implications and applications in medicine, cosmetics and possibly also in other fields. 

The calculated solubility parameter derived from the Van Krevelen approach has been compared with the experimental solubility parameters of C60 and C70 reported in the literature and derived experimentally. An excellent agreement has been found between the calculated and the experimental <5d values. A comparison with the calculated solubility parameter of the vegetable oils, under certain conditions, permits to show that a good solubility of fullerenes in glycerol esters of fatty acids can be expected. Fulleiene solubility in molten free fatty acids can be predicted on the basis of solubility parameters comparison and it has been verified by dissolving C60 and C70 in molten fatty acids. 

The ketone bodies are released by the liver into the blood, in which they are easily soluble. Blood levels of ketone bodies therefore rise during periods of hunger. Together with free fatty acids, 3-hydroxybutyrate and acetoacetate are then the most important energy suppliers in many tissues (including heart muscle). Acetone cannot be metabolized and is exhaled via the lungs or excreted with urine. 

Classically, lipases hydrolyse ester bonds in emulsified esters, i.e. at a water/oil interface, although some may have limited activity on soluble esters they are usually activated by blood serum albumin and Ca2 + which bind free fatty acids, which are inhibitory. Little lipolysis normally occurs in... 

In vertebrates, free fatty acids (unesterified fatty acids, with a free carboxylate group) circulate in the blood bound noncovalently to a protein carrier, serum albumin. However, fatty acids are present in blood plasma mostly as carboxylic acid derivatives such as esters or amides. Lacking the charged carboxylate group, these fatty acid derivatives are generally even less soluble in water than are the free fatty acids. 

As hormone-sensitive lipase hydrolyzes triacylglyc-erol in adipocytes, the fatty acids thus released (free fatty acids, FFA) pass from the adipocyte into the blood, where they bind to the blood protein serum albumin. This protein (Mv 66,000), which makes up about half of the total serum protein, noncovalently binds as many as 10 fatty acids per protein monomer. Bound to this soluble protein, the otherwise insoluble fatty acids are carried to tissues such as skeletal muscle, heart, and renal cortex. In these target tissues, fatty acids dissociate from albumin and are moved by plasma membrane transporters into cells to serve as fuel. 

The mixture of lipids moves to the endoplasmic reticulum, where fatty acyl CoA synthetase converts free fatty acids into their activated CoA derivatives. Fatty acyl CoAs are then used to produce triacylglycerols, cholesteryl esters, and phospholipids. These, together with the fat-soluble vitamins (A, D, E, and K) and a single protein (apolipoprotein B-48), form a chylomicron, which is secreted into the lymphatic system and carried to the blood. 

Paprika can be extracted to recover carotenoids, not only with CO2 but also with other gases. For example, by using ethane or ethylene, better results were obtained for the yield, extraction time, and quality of product. The solubilities of carotenoids are better in these gases, which is why the consumption of solvent and the extraction time were reduced. Practically water-free dye-concentrate was recovered by supercritical fluid ethane (under the conditions extraction 250 bar, 45°C separation 46 bar, 45 °C). The separation of pungent substances (capsaicinoids, free fatty acids) from the pigments can be carried out effectively in a continuous, counter-current extraction column with a large number of theoretical plates. 

In terms of composition, Table 7.5 shows that milk fat consists primarily of triglycerides with small amounts of di- and monoglycerides, phospholipids, sterols such as cholesterol, carotenoids, fat-soluble vitamins A, D, E, and K, and some traces of free fatty acids (Renner 1983 Christie 1983). The fatty acid composition of bovine milk fat is characterized by a high proportion of saturated fatty acids (60 to 70%), appreciable amounts of monounsaturated fatty acids (25 to 35%), and small amounts of polyunsaturated fatty acids (4%) (Lampert 1975). Milk fat... 

The names and structures of some fatty acids are summarized in Table 8-1. Notice that these acids have straight carbon chains and may contain one or more double bonds. Except for the smallest members of the series, which are soluble in water, fatty acids are strongly hydrophobic. However, they are all acids with pKa values in water of 4.8. To the extent that free fatty acids occur in nature, they are likely to be found in interfaces between lipid and water with the carboxyl groups dissociated and protruding into the water. However, most naturally occurring fatty acids... 

Extraction of nonpolar compounds using equal volumes of sample and the Folsch mixture (2 1, chloroform/MeOH) gives a very broad polarity cut. Everything from steroids to triglycerides is pulled down into the bottom chloroform-rich layer. Extraction with methylene chloride from a sample acidified with sulfuric acid is more specific, pulling in steroids, fat-soluble vitamins, and free fatty acids. The triglyceride fraction can be extracted using i-PrOH/ hexane (1 9) with little emulsification. 

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