Fatty free, analysis

Aldehydes, enals, dienals, ketones, and hydrocarbons, which are responsible for disagreeable odors, generally bok at lower temperatures than fatty acids. Analysis showkig a free fatty acid concentration of less than 0.05% is an kidication that deodorization is sufficientiy complete. Some of the dienals have very low odor thresholds and sensory evaluation of the finished ok is a judicious quaHty assurance step. 

Greco, A. V., Mingrone, G., Gasbarrini, G. Clin. Chim. Acta 239, 1995, 13-22. Free fatty acid analysis in ascitic fluid improves diagnosis in malignant abdominal tumors. 

Fatty acid analysis of a fat is nowadays a relatively routine analytical operation. After methylation of the fat using reaction with boron trifluoride/methanol, boron trichloride/methanol, methanolic hydrogen chloride solution, diazomethane or, if free fatty acids are not present, alkaline catalysts such as sodium methoxide/methanol, the prepared methyl esters are then analysed by GC on a polar column such as CpSil 88, BPX70 or SP2340. The high polarity of the column is necessary to separate the saturated and unsaturated fatty acids fully. The fatty acid composition of a milk fat sample is thus relatively easily obtained, and was therefore one of the first techniques investigated for authentication purposes. 

The samples were analysed by capillary gas chromatography GC 6000 (Carlo Erba) with FFAP-CB phase (Chrompack) that is special for free fatty acid analysis. The FID temperature was 235°C, the injector was an on-column system and the oven gradient was 40°C during 2 min, then increasing to 210°C at 45°C/min. The injected quantity was 2pl with no dilution. 

Composition of fatty acids. The saturated and unsaturated fatty acids with 8 to 24 carbon atoms in animal fats, vegetable oils, marine oils, and fatty acids are quantitatively determined by gas chromatography (GC) after conversion to their methyl ester forms. However, free fatty acid analysis is also possible by using specially selected stationary solid... 

The role of fatty adds in the etiology of atherosclerosis is far from clear. It has often been suggested that excess saturated fats or carbohydrates in the diet are related to the development of atherosclerosis. Animals that live free in the woodland areas where they eat a great variety of foods including nuts, berries, seeds, etc., get a more oil-rich diet and have considerably moM polyunsaturated fatty acid in their tissues than animals in captivity. Fatty acid analysis was made of abdominal sucutaneous adipose tissue of men that died suddenly and the coronary disease evaluated under standardized procedures. The analyzed fatty acids listed in order of their relative contributions to the extent of the disease are stearic, lauric, palmltolelc, myrlstlc, and llnolelc. 

Rozes, N., C. Gargia-Jares, F. Larue, and A. Lonvaud-Funel. 1992. Differentiation between fermenting and spoilage yeast in wine by total free fatty acid analysis. /. Sci. Food Agric. 59 351-357. 

The acyl groups can either be isolated as free fatty acids by alkaline hydrolysis or as their methyl esters by acid catalyzed transesterification. The most common, elegant and reHable method of fatty acid analysis is gas chromatography of the methyl esters (Lipsky et al. 1963). 

In addition to sensory evaluation, free fatty acid analysis (the content is usually below 0.05%) and analysis of possible contaminants are carried out. The data given in Table 14.15 illustrate the amounts of pesticides and polycyclic aromatic compounds removed hy deodorization. However, this refining step also removes the highly desirable aroma substances which are characteristic of some cold-pressed oils such as olive oil. 

In another frying trial by Xu et al. (1999), three HOLL canola oils with different levels of linolenic acid and HOSO were compared with commercial PO. The oils were heated over a period of 80 h at 190°C by frying potato chips. Fatty acid analysis, iodine value, colour index, dielectric constant, free fatty acids and the total polar compounds were used for the assessment of the suitability of the oils. Additionally, a sensory evaluation was carried out... 

Oils are mixtures of mixed esters with different fatty acids distributed among the ester molecules. Generally, identification of specific esters is not attempted instead the oils are characterized by analysis of the fatty acid composition (8,9). The principal methods have been gas—Hquid and high performance Hquid chromatographic separation of the methyl esters of the fatty acids obtained by transesterification of the oils. Mass spectrometry and nmr are used to identify the individual esters. It has been reported that the free fatty acids obtained by hydrolysis can be separated with equal accuracy by high performance Hquid chromatography (10). A review of the identification and deterrnination of the various mixed triglycerides is available (11). 

The purity of the product was determined by the checkers by GLC analysis using the following column and conditions 3-nm by 1.8-m column, 5% free fatty acid phase (FFAP) on acid-washed chromosorb W (60-80 mesh) treated with dimethyldichlorosilane, 90 C (1 min) then 90 to 200 C (15°C per rain). The chromatogram showed a major peak for methyl 2-methyl-l-cyclohexene-l-carboxylate preceded by two minor peaks for methyl 1-cyclohexene-l-carboxylate and l-acetyl-2-methylcyclohexene. The areas of the two impurity peaks were 5-6% and 0.5-2% that of the major peak. The purity of the product seems to depend upon careful temperature control during the reaction. The total amount of the two impurities was 14-21% in runs conducted at about -15 to -20°C or at temperatures below -23°C. 

Alkaline hydrolysis (saponification) has been used to remove contaminating lipids from fat-rich samples (e.g., pahn oil) and hydrolyze chlorophyll (e.g., green vegetables) and carotenoid esters (e.g., fruits). Xanthophylls, both free and with different degrees of esterification with a mixture of different fatty acids, are typically found in fruits, and saponification allows easier chromatographic separation, identification, and quantification. For this reason, most methods for quantitative carotenoid analysis include a saponification step. 

It is of interest to examine the development of the analytical toolbox for rubber deformulation over the last two decades and the role of emerging technologies (Table 2.9). Bayer technology (1981) for the qualitative and quantitative analysis of rubbers and elastomers consisted of a multitechnique approach comprising extraction (Soxhlet, DIN 53 553), wet chemistry (colour reactions, photometry), electrochemistry (polarography, conductometry), various forms of chromatography (PC, GC, off-line PyGC, TLC), spectroscopy (UV, IR, off-line PylR), and microscopy (OM, SEM, TEM, fluorescence) [10]. Reported applications concerned the identification of plasticisers, fatty acids, stabilisers, antioxidants, vulcanisation accelerators, free/total/bound sulfur, minerals and CB. Monsanto (1983) used direct-probe MS for in situ quantitative analysis of additives and rubber and made use of 31P NMR [69]. 

Poly(3HAMCL)s have also been produced from free fatty acid mixtures derived from industrial by-products which are potentially interesting low-cost renewable resources. Isolation and analysis of the polymer allowed the identification of 16 different saturated, mono-unsaturated and di-unsaturated monomers [46]. Except for the presence of diene-containing monomers and a large number of minor components, the composition of the fatty acid mixture derived PHA did not differ significantly from oleic acid derived PHAs. 

In addition to these numerous results, two other points are discussed by the authors fatty acid speciation and oil identification. These two aspects are developed in another publication written by the same authors [Keune et al. 2005]. The fatty acid speciation is based on the positive ion ToF-SIMS analysis and aims to prove if the fatty acids detected exist as free fatty acids, ester bound fatty acids or metal soaps. On account of the study of different standards, it is shown that when free fatty acids are present, the protonated molecular ion and its acylium ([M-OH]+) ion are detected. In cases of ester-bound fatty acid only the... 

In addition to neutral loss scans, mass spectrometers can be used to detect other compounds in a different manner. Acylcamitines are fatty acid esters of carnitine. The masses of acylcamitines differ by the size of the fatty acid attached to it. The tandem mass spectrometer can detect these selectively as well because they all produce a similar product, in this case an ion rather than a molecule. Because it is an ion, it can be detected by the second mass separation device. The ion has a mass of 85 Da and is common to all acylcamitines. Performing a precursor ion scan of 85 Da (essentially a scan of only molecules that produce the 85 ion) reveals a selective analysis of acylcar-nitines, as shown in Fig. 14.2. Additional scans have been added to more selectively detect basic amino acids, free carnitine, short chain acylcamitines and a hormone, thyroxin (T4) which has amino acid components. 

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