Standardization of spectrophotometric methods for determination of polyunsaturated fatty acids using pure natural acids

Brice, B. A.; Swain, Margaret L.; Herb, S. F.; Nichols, Peter L.; Riemenschneider, R. W.

doi:10.1007/bf02631475

Cited by 114 publications

(24 citation statements)

References 19 publications

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“…The deviations are presumably due to chance errors as well as t o differences in the analyticd procedures. Similar results were found by Brice et al ( 4 ) in applying these and other procedures t o samples of beef tallow and lard containing less than 1% linolenic acid. Published linolenic acid analyses of normal domestic animal f a t s For sausages and similar products, an allowance must also be made for the linolenic acid present in the oil contributed by cereal fillers, such as wheat, rice, oat, corn, or soybean flours.…”

Section: Resultssupporting

confidence: 87%

“…Justification for this allowance is afforded b r data given in the Report of the Spectroscopy Committee of the American Oil Chemists' Society (24) and by results presented by Brice, Swain, Herb. Nicholas, and Riemenschneider ( 4 ) . The former reference gives the resuls of a collaborative study, comparing, among others, the Brice and Swain procedure with the Beadle and Kraybill method; for samples of soybean oil containing about 8% linolenic acid, the total spread of all results by all methods was less than 15% of the average value.…”

Section: Resultsmentioning

confidence: 99%

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DETECTION OF HORSEMEAT IN MEAT PRODUCTS BY A MODIFIED PASCHKE METHOD^a

Grouse¹,

Leffler²

1953

Journal of Food Science

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I n 1938, Paschke (23) introduced a method f o r detection of horsemeat in admixture with beef, mutton, o r pork, based on the observation that horse fat is richer in linolenic acid than are the depot fats of other large domestic animals. According to this procedure, the hexabromide number of the mixed fatty acids is used as a measure of the percentage of linolenic acid in the fat extracted from the meat sample under investigation. Variations of the Paschke procedure have been used by Fisher (14), Crowell (9), Dalley ( l o ) , and by Hynds (19,20). These workers report hexabromide values ranging from 4.1 to 21.5 for horsefat, and from 0.1 to 1.0 for beef, mutton, and pork fats. The chief difficulty mentioned by these authors is the poor reproducibility of the hexabromide method. Hynds (20) found that hexabromide values from 1.4 t o 4.0 were obtained when identical mixtures of horsemeat and beef were analyzed by several independent workers, using the same procedure.This paper describes a modified Paschke procedure, whereby ultraviolet spectrophotometry is used t o determine the percentage of linolenic acid in the fat extracted from meats and sausages. I n recent years, this method has generally supplanted other procedures for analysis of fats for polyunsaturated acids, particularly in instances where a high degree of accuracy is required. EXPERIMENTAL METHODSThe experimental work forming the basis of this paper included a study of extraction procedures in order to arrive at a standard analytical procedure which gives precise results for the percentage of linolenic acid in the f a t obtained from undried meat, and the application of this procedure to meats and sausages.Preliminary studies. Moderately lean chuck meat from U. S. inspected beef (sample 4), and lean horse flank meat (sample 10) were used t o determine the effects of cooking and of extraction conditions on the percentage of linolenic acid found in the extracted fat. About 500 g. of each material was passed 3 times through a handoperated food chopper, which is equipped with a cutter blade, and which has an extrusion plate with %-inch perforations. The meat was quartered and kneaded after each passage through the chopper.Approximately 25 g. of the chopped beef or horsemeat was used for each extraction study. Single-thickness thimbles were used f o r the Soxhlet extractions; the samples to be cooked were weighed in the thimbles, and the Sled thimbles were placed for one hour in an air oven maintained at 90°C. Thus, the percentages of extracted f a t given in Table 1 are based on the weights of the original uncooked and undried samples. The extractions were carried out in all-glass equipment, using diethyl ether or petroleum ether (b. 30-60°C.) for either 3 or 5 hours. The heating rate was adjusted so that siphoning occurred 1 2 t o 15 times per hour.Extractions were also carried out by maceration of the chopped meat samples with ice and solvent in a Waring blendor. The blendor jar was charged with about 50 ml. 'Sponsored in part by the Cudahy Packing Compa...

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Section: Resultssupporting

confidence: 87%

Section: Resultsmentioning

confidence: 99%

DETECTION OF HORSEMEAT IN MEAT PRODUCTS BY A MODIFIED PASCHKE METHOD^a

Grouse¹,

Leffler²

1953

Journal of Food Science

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“…Polyunsaturated acids were measured using the 45-rain. isomerization of Briee et al (3). Triene conjugation was observed but may possibly be the result of minor oxidative change.…”

Section: Methodsmentioning

confidence: 82%

“…p REVIOUS investigators have attempted to improve the resistance of extracted animal fats to the onset of rancidity by alteration in the antioxidant composition of the diet. The natural antioxidants, the tocopherols, can be deposited in the fat of the rat (2,19,10,3,20), swine (4, 5, 33), rabbit (22), turkey (6,23,24,25), and chicken (24, 25, 11). Providing the fatty acid composition is constant, the stability of the extracted fat depends upon the tocopherol content of the diet.…”

mentioning

confidence: 99%

Glyceride structure of vegetable oils by countercurrent distribution. III. Safflower oil

Scholfield

Dutton

1958

J Americ Oil Chem Soc

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Summary Safflower oil was fractionated in a 200‐tube countercurrent distribution apparatus, and the oil was also fractionated after interesterification with C14‐labelled palmitic acid. The glyceride composition of the interesterified oil was similar to that of the natural oil. The glycerides were separated on the basis of both unsaturation and chain length of the constituent fatty acids, and the palmitoglycerides had only slightly higher partition coefficients than the oleoglycerides. The amounts of trilinolein, oleodilinolein, and palmitodilinolein found were similar to those calculated for a random distribution. Distribution of a mixture of safflower oil and olive oil showed that no mixing or randomization of triglycerides occurred during countercurrent distribution. It is concluded that fatty acids in safflower triglycerides are distributed in an essentially random pattern.

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“…Since the fatty acids differ in molecular size and in degree of unsaturation, the results of the analyses are also presented on a mol basis and per unit of unsaturation per mol. In the case of the butterfat, results are expressed only in terms of those polyunsaturated fatty acids found by spectrophotometric analysis (2) to be present. Jars containing paraffin wax alone were similarly stored for control purposes.…”

Section: Extinction Ratiomentioning

confidence: 99%