Total fatty acid content, determining

Acidulated soybean soapstock is the product obtained from the complete acidulation and thorough setting of soapstock, which itself is the by-product obtained from the alkali refining of soybean oil. It is sold on a basis of 95% total fatty acid content. If it falls below 85% total fatty acid content, it may be rejected. Typical analyses are TFAs, 90% moisture, 1% and iodine value 125. In practice, soybean soapstock may be found in combinations with other vegetable oil soapstocks. The buyer should determine if cottonseed soapstock is present, as it may contain gossypol, which is detrimental in nonruminant feeds. Physical properties are medium brown color odor somewhat typical of soybeans, slightly nutty solid when cool and liquid and pumpable at 38 14°C (100-110°F). It qualifies under AAFCO 33.3, IFN 4-17-893 (31). 

Very few determinations have been made of the total fatty acid content of marine waters. Of the few methods available, a technique which is reported to be reliable is that of extraction of the free acids with chloroform at pH 2 followed by formation of a copper complex and final estimation of the complexed copper by atomic absorption spectrophotometry (Treguer et al., 1972). The free fatty acid contents are reported as palmitic acid equivalents. The method, however, has not yet been widely adopted for routine use. 

Zhou, S. and Ackman, R.G. 1996. Acidity of polar lipids and their interferences with the determination of free fatty acid content in total lipids. J. Am. Oil Chem. Soc. 73 1019-1023. 

Assay Preparation Transfer about 4 g of sample, accurately weighed, into a 250-mL Erlenmeyer flask, and add 80 mL of 0.5 N potassium hydroxide and 0.5 mL of phenolphtha-lein TS. Connect an air condenser at least 65 cm long to the flask, and heat the mixture on a hot plate for about 2.5 h. Remove the air condenser and add approximately 10% phosphoric acid to the hot mixture until it is definitely acid to Congo red test paper. Reconnect the air condenser, and heat until the fatty acids are liquified and clear. Cool, and transfer the mixture into a 250-mL separator with the aid of small portions of water and hexane. Extract the liberated fatty acids with three successive 25-mL portions of hexane, and collect the extracts in a second separator. Wash the combined hexane extracts with two 25-mL portions of water, and add the washings to the separator containing the water layer. Retain the combined hexane extracts for the determination of total fatty acids. Transfer the contents of the first separator to a 250-mL beaker, heat on a steam bath to remove traces of hexane, filter through acid-washed, fine-texture filter paper into a 500-mL volumetric flask, and finally dilute to volume with water (Solution I). Pipet 25.0 mL of this solution into a 100-mL volumetric flask, and dilute to volume with water (Solution II). Retain the rest of Solution I for the determination of Glycerin (below). 

In some cases, a given step can be coupled on-line with USAL but off-line development provides better results. Such is the case with a method for the determination of the frans-fatty acid content in bakery products [32] following isolation of total fat, the fatty acids must be derivatized to methyl esters, which are volatile, for subsequent analysis by gas chromatography separation with mass spectrometry as detection system. The derivatization reaction must be complete, selective and sensitive enough, which is difficult to accomplish in a continuous manner as the procedure involves ... 

Bailey (23) noted that the composition of American cottonseed oils will rarely fall outside of these limits 23-28% total saturated fatty acids, 22-28% oleic acid, and 44-53% linoleic acid. The Food and Agriculture Organization of the World Health Organization (FAO/WHO) has determined a range of fatty acid contents for commercial fats and oils. The acceptable range of fatty acids prescribed by Codex in 1997 for cottonseed oil is shown in Table 6 (77). 

Several studies have confirmed that the seed oil from the North American variety of cranberry contains significant levels of a-linolenic acid. In a U.S. patent, Heeg et al. (4) reported the a-linolenic acid content of cranberry seed oil to be between 30% and 35% of total fatty acids. In 2003, Parker et al. (5) found 22.3% a-linolenic acid in the cold-pressed cranberry seed oil, and in 2004, Parry et al. (3) determined the oil to contain 32.0% a-linolenic acid from two different lots of the seed oil. The ratios of n-6 to n-3 fatty acids in all were low from 1.2 1 to 2 1. Also, all of the studies documented similar ratios among the rest of the common fatty acids found in cranberry seed oil, including, in order of higher amount present linoleic, oleic, palmitic, stearic, and eicosadienoic (20 2) acids (Table 1). In addition to a-linolenic acid, cranberry seed oil is rich in natural antioxidants (8). These antioxidants may directly react with free radicals and prevent lipid oxidation in human low-density lipoprotein. 

Lipase-catalyzed hydrolysis of the vitamin esters in food samples in SCCO2 has been investigated as a pretreatment step in the analytical determination of vitamins in food samples (216, 217). Lipase-catalyzed transesterification of oils with methanol have been used for the determination of total fat content in lipid-containing samples such as oilseeds and meat samples (218, 219) and for the determination of fatty or resin acid content of tall oil products (220). Esterification of fatty acids with methanol in SCCO2 has been reported for total fatty acid analysis of soapstock (221). 

The many methods of pre-esterification would complement the described process by allowing the use of acylglycerols with higher fatty acid content. The benefits of such methods may then be determined independent of a total process. 

Treguer, P., Le Corre, P. and Courtot, P., 1972. A method for determination of the total dissolved free fatty-acid content of sea water. J. Mar. Biol. Assoc. U.K., 52 1045— 1055. 

Hydrolysis of polyamide-based formulations with 6 N HC1 followed by TLC allows differentiation between a-aminocaproic acid (ACA) and hexamethylenedi-amine (HMD) (hydrolysis products of PA6 and PA6.6, respectively), even at low levels. The monomer composition (PA6/PA6.6 ratio) can be derived after chromatographic determination of the adipic acid (AA) content. Extraction of the hydrolysate with ether and derivatisa-tion allow the quantitative determination of fatty acids (from lubricants) by means of GC (Figure 3.27). Further HC1/HF treatment of the hydrolysis residue, which is composed of mineral fillers, CB and nonhydrolysable polymers (e.g. impact modifiers) permits determination of total IM and CB contents CB is measured quantitatively by means of TGA [157]. Acid hydrolysis of flame retarded polyamides allows to determine the adipic acid content (indicative of PA6.6) by means of HPLC, HCN content (indicative of melamine cyanurate) and fatty acid (indicative of a stearate) by means of GC [640]. Determination of ethylene oxide-based antistatic agents... 

Regarding the interference of lipids and fatty acids in preparation of LPC, Nagy et al. (15) made an extensive study of this problem and determined, as indicated in Table VII, that the lipid content and total lipid distribution in some green protein fractions is indeed significant and can present a problem with protein extractability and purification. They indicated however, most of the lipid appeared to come from extraction of cell walls and ruptured cellular contents during the maceration process. 

In many tissues cholesterol and other sterols exist as a mixture of the free alchohol and its long chain fatty acid ester (esterified at position 3 of the steroid nucleus). The determination of the cholesterol content of a sample may involve the measurement of either of these two fractions individually or the total cholesterol. It is possible to precipitate free cholesterol by adding an equal volume of digitonin (1 gl-1 in 95% ethanol), a naturally occurring glu-coside, to form a complex that is insoluble in most solvents, including water. 

Both maternal and infant factors determine the final amount of drug present in the nursing child s body at any particular time. Variations in the daily amount of milk formed within the breast (e.g., changes in blood flow to the breast) as well as alterations in breast mUk pH wUl affect the total amount of drug found in mUk. In addition, composition of the milk will be affected by the maternal diet for example, a high-carbohydrate diet will increase the content of saturated fatty acids in milk. 

While an analysis of individual components in morama beans (above) can give a good lead to their possible beneficial and negative effects, it is the sum total, antagonistic or synergistic effects of the various component combinations which determine their overall effect on health. It is the high content of amino acids, and some fatty acids, complemented with minor... 

Potatoes are not regarded as an important source of lipids, because the lipid content of the tuber is very low, ranging from 0.2 to 2 g (1.2 g on average) per kg on a fresh weight basis (OECD, 2002). The flesh of boiled potato cooked in skin without salt contains about 0.1 g total lipids, 0.03 g total saturated fatty acids, 0.002 g total monounsaturated fatty acids, and 0.043 g total polyunsaturated fatty acids per 100 g (USDA, 2007). The Adequate Intake determined for the essential n-6 and n-3 polyunsaturated fatty acids is for adults 11-17 and l.l-1.6g per day, respectively (Food and Nutrition Board, 2005). 

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