Fat. analysis

Both the light scattering and infrared techniques are widely used, and there are many reports of the correlation between one of these methods and a reference method, usually Babcock or Gerber in the case of fat analysis and total nitrogen by Kjeldahl for proteins. One source of disparity between the various correlations has been the choice of a reference method. The realization that different methods for fat analysis measure different chemicals and thus can be expected to give different results has been slow in reaching the industry. 

Konev, S. V. and Kozlova, G. G. 1970. Application of secondary luminescence for fat analysis in milk and some dairy products. Proc. 18th Int. Dairy Congr. IE, 84. 

In recent years, more efficient ATR accessories that are suitable for quantitative analyses were developed. In particular, small diamond ATR crystals that have a capacity of — I pi have been successfully tested and are recommended for trans fat analysis. 

Do You Know Your Percent Body Fat Find out with our Body Fat Analysis Private and convenient State-of-the-art technology S10 off Body Fat Analysis (Discounted price 55)... 

Each service will be available as a complete program or as separate service components. The complete Stay Fit Program will cost 130, which includes one of each of the three services. Separate component costs are body-fat analysis ( 65), resting metabolic rate ( 60), and nutritional counseling ( 35). The basic Med Check Program will cost 95, which will include an evaluation of the patient s medications (including a written report), patient education for identified... 

The services will be provided in a new service area in the Feel Great Pharmacy. The service area will contain testing equipment, a computer, chairs, and a workspace. It will be made private through the use of cubicle dividers. Pharmacists will provide most of the services, except the body-fat analysis and resting metabolic rate assessments, which will be provided by a medical technician. An appointment system will be used so that extra staff can be present during delivery of the new services. 

Many of the tests described involve physical properties such as refractive index, viscosity or melting point of the fat, of the fatty acids or of the lead salts of the fatty acids. However, there were also many chemical tests such as Reichert, Polenske, iodine, saponification and acetyl values. These all gave information as to the composition of the fat, some information as to fatty acid composition, others as to other non-glyceride components of the fat. Thus the iodine value is a measure of unsaturated fatty acids in the fat, now obtainable in more detail from a fatty acid profile. Similarly the Reichert value is a measure of volatile fatty acids soluble in water. For most purposes this means butyric acid, and so the modem equivalent is the determination of butyric acid in the oil. The modem method for milk-fat analysis is thus carrying out the analysis in a similar way to the Reichert determination, but uses a technique that is less dependent on the exact conditions of the analysis and is thus less likely to be subject to operator error. The Reichert value could be useful, in theory, even if milk fat was not present. Lewkowitsch notes that some other oils do give high values. Porpoise jaw oil has a value almost twice that of milk fat, while some other oils also have significant values. It is unlikely that one would have come across much porpoise jaw oil even in 1904, and even less likely today. 

Compiled from NRA, Pocket Information Manual A Buyer s Guide to Rendered Products. National Renderers Association, Inc., Alexandria, VA. 2003. bFAC = Fat Analysis Committee, AOCS. 

If starch is present when an oilseed is extruded, the fat and starch will form a complex that is not soluble in ether, the normal method used for fat analysis. Studies have shown that fat will enter a complex with starch on the basis of a 1 to 10 ratio. An acid hydrolysis is necessary to measure the correct and actual fat level in such a case. 

The bleaching of rendered fats, typically using commercially available bleaching clays, is done to remove color bodies and other contaminants that darken the color of the fat. Raw rendered fats are usually described by FAC (the Fat Analysis Committee of the American Oil Chemists Society) colors as outlined by the American Oil Chemists Society (AOCS) Method Ccl3a-43. The AOCS notes that the 1992 version was declared obsolete and was removed from the book of methods in 1993. However, its use is not precluded and its official method status is not changed. 

Fats, analysis of 961 Fatty adds, determination of 936 Feces, phenolic compounds in, determination of 969... 

Oil content determination is usually performed by Soxhlet solvent extraction this usually takes up to 4h, but it is the standard method recommended by the AOAC. On the other hand, a method called Foss-Let takes only 5-10 min to determine the fat content in meat products. The typical error associated with this method is reported to be less than 1% when compared to the standard AOAC method (Kroff, 1984). Several other methods of fat analysis include nuclear magnetic imaging (NMI) and electronic meat-measuring equipment (EMME), which can be used for measuring the fat content in lean meat at an accuracy of 0.1%-0.2% of the official method (Kroff, 1984). It functions on the basis of the difference in electrolyte components of lean and fat components. Another method is the Vico-fat measuring system, which uses a perchloroethylene agent (Pettinati, 1982) and the HSI technique. Some of these techniques are rapid and amenable to online, real-time control. 

Kroff, D. H. (1984). New rapid methods for moisture and fat analysis A review. Journal of Food Quality, 6(3), 199-210. 

Direct measurement of thermal fat crystal properties NMR imaging of dairy products Acidification of pressure-treated milk Characterization of semi-solid state in milk fat Analysis of Maillard products in milk... 

Cocks and Van Rede (1966) Laboratory Handbook for Oil and Fat Analysis, Academic Press. 

Table 4 Sample dimensions for edible oil and fat analysis (FAMEs and TAGs)...

Figure 13.1 Fat analysis on a column (150 x 4.6mm) with polymer PLRP-S (lOOA, 5 pm). Mobile phase (A) 48% THF, 10% MeOH, 42% water (B) 85% THF, 10% MeOH, 5% water gradient 0-100% B in 20 min. (1-4) Monoglyceride, (5-10) diglyceride, (11-14) triglyceride. (From [188].)...

FAC, Fat Analysis Committee of the American Oil Chemists Society colour standards, range 1- 5 (45 darkest). 

Many rapid methods are now available for estimation of fat content. The Foss-Let fat analysis system determines the fat content as a function of relative density of a perchloroethylene extract of the sample. It was designed for analysis of oilseeds, but is also applicable to other foods. The method is very rapid and its accuracy is comparable to other standard methods. Nuclear magnetic resonance (NMR) spectrometry is a rapid, nondestructive method also suitable for determining the fat content of oilseeds. The NMR value is related to the total hydrogen content of the lipid, with actual lipid content calculated from calibration tables. 

Todt, H., Guthausen, G., Burk, W., Schmalbein, D., Kamlowski, A. 2006. Water/moisture and fat analysis by time-domain NMR. Food Chem. 96 436-440. 

Some of the frequently used colour reactions of classical fat analysis, like the Halphen-test, can be carried out on the adsorbent layer after thin-layer fractionation this enables us to discover which substances are responsible for these colour reactions [144]. The sterol fraction is especially easily identified with various spray reagents (see Chapter L) and functions thus as a characterising feature ( marker ). 

The methods used for determination of fat or oil in food are often based on extraction with either ethyl ether or petroleum ether and gravimetric determination of the extraction residue. These methods may provide unreliable or incorrect results, particularly with food of animal origin. As shown in Table 14.20, where a corned beef sample was analyzed, the amount and composition of fatty acids in the fat residue were influenced greatly by the analytical methods used. In addition to the accessible free lipids, the emulsifiers present and the changes induced by autoxidation affect the amount of extractable lipids and the lipid-to-nonlipid ratio in the residue. The use of a standard method still does not eliminate the disadvantages shown by analytical methods of fat analysis. Therefore, in questionable cases, quantitative determination of fatty acids and/or glycerol is recommended. 

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