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February, 1945
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Rapid Determination of Fat in M e a t and M e a t Products R. B. OESTING AND 1. P. K A U F M A N , Oscar M a y o r & Co., Chicago, 111.
THE
need for a rapid control method for fat determinations in meat food products has led to the development of a modified Babcock technique. The method is simple and rapid, giving results sufficiently accurate for the control of manufacturing operations. The time required for a determination, when one Waring mixer is used, is about 30 minutes.
APPARATUS. The apparatus required consists of a Waring mixer, Babcock bottles (8%, l&gram, calibrated in O.l%), cream pipet, 10-rnl. graduate, and Babcock centrifuge. REAQENTS.The reagents are C.P. sulfuric acid (specific gravity 1.84),glacial acetic acid, and household Oakite. PBOCEDURE. Weigh out 25 grams of the finely ground sample, and place in a Waring mixer. Add 100 grama of cracked ice or water at l o to 3” C., and 2 grams of household Oakite. Run mixer 10 minutes with cover in place, stopping occasionally, to swirl contents and dislodge any lumps of meat which may adhere to the sides of the container. After thorough mixing, weigh 10 grams of the emulsion to the nearest 0.1 gram into a Babcock bottle. Add 5 ml. of glacial acetic acid, and mix thoroughly in order to coagulate the protein. Then add 10 ml. of concentrated sulfuric acid, a little a t a time, and swirl until all lumps are dissolved. At this point, add just enough hot water to form a layer above the acid mixture. The fat rises above the water layer, and charring is reduced to a minimum. Next, add 5 ml. more of sulfuric acid, and mix. Centrifuge for 5 minutes a t a proximately lo00 r.p.m., then add hot water to the neck of the [ottle, and centrifuge 2 minutes. Finally, add
Table 1.
Corn eriron
d Modified Babcock Method with Standard A.8.A.C. Soxhlrt Extraction for Fat in M e a t
Sample Chopped ork Chopped gam Pork sausage links Wieners Chopped ham Bulk pork aausage Chopped ham
Bulk pork aauage
Chopped ham Wienen
Pork n a w e Unlu
A.O.A.C. Ether Extraction
Babcock T. Method
%
%
21.3 27.3 41.b 26.2 27.0 25.9 2b.6 48.6 2b.6 4b.b 49.1 24.6 27.7 26.3 22.1 22.2 16.0 22.0 22.1 41.0
25 6 28.4 41.4 24.9 28.9 28.7 26.1 48.2 26.2 46.5 47.6 24.9 27.1 2b.8 22.4 22.6 26.3 22.3 21.8. 41.4
Table II. Reproducibility of Method Determination No.
% Fat
1 2 3 4
26.8 26.3 28.2 26.9
hot water to within 1 to 2 cm. of the top of the neck, and centrifuge 1 minute. Immerse the bottle in water a t 70” C., and read after 2 minutes, on a descending fat column. The column will begin to descend when the bottle is removed from the water bath. The column should be read from the top of the upper meniscus to the bottom of the lower meniscus, a plying the calibrations on the bottle for thia measurement. M s i p l y directly by 9.2, in order to convert to per cent of fat. A correction must be applied for the difference from exactly 10.0 grams in the weight of the sample used. Comparisons were made between the official A.O.A.C. fat extraction method (I) and this rapid method. Samples run included chopped ham, chopped pork, bulk pork sausage, and wieners (natural and artificial casings), the fat content of which ranged from 20 to 50%. Based on a n average level of 30% fat, the new method showed a standard deviation of *0.7% with a probable error of *0.5%, when compared to the A.O.A.C. method. The comparative figures are given in Table I. The difference between the Babcock values.given above, and the values obtained by multiplying the reading on the Babcock bottle by 9.2, is caused by the fact that where exactly 10.0 grams of sample were not used, the fat values were corrected to exactly 10.0 grams. The reproducibility of the method is indicated in Table 11. Four separate determinations were made on the same sample. The maximum variation between determinations in this range was 0.7%. This method gives satisfactory results with all types of fresh or cooked meat items, with the exception of foods of high cereal content. The cereal is not digested and forms a layer below the fat layer which interferes with the determination. In such a case, satisfactory results have been obtained by immersing the bottle in boiling water. The fat layer usually riees above the cereal, and satisfactory readings are obtained. LITERATURE CITED (1) h o c . Official Agr. Chem.. Official and Tentative Methods of Analysis, 5th ed., p. 356. 1940.
