Collaborative Study of the Colorimetric Determination of Sorbic Acid in Cheese

1971 ◽  
Vol 54 (3) ◽  
pp. 663-665
Author(s):  
George Wilamowski
Keyword(s):  
Steam Distillation ◽  
Sorbic Acid ◽  
Potassium Dichromate ◽  
Collaborative Study ◽  
Thiobarbituric Acid ◽  
Colorimetric Determination ◽  
Red Color ◽  
Red Dye ◽  
532 Nm

Abstract After isolation of sorbic acid from cheese by steam distillation, the acid recovered is cleaved with potassium dichromate in acidic medium to form an intermediate malonaldehyde, which, in turn, reacts with 2-thiobarbituric acid to produce a red dye. The absorbance of the red color, measured at 532 nm, is proportional to the concentration of sorbic acid in the sample. Seven collaborators reported recoveries of 96.7–102.4% from cheese samples spiked with 0.05% sorbic acid. This method has been adopted as official first action.

Determination of Sorbic Acid in Wine

1974 ◽  
Vol 57 (4) ◽  
pp. 951-953
Author(s):  
Arthur Caputi ◽  
Masao Ueda ◽  
Bruno Trombella
Keyword(s):  
Steam Distillation ◽  
Acidic Solution ◽  
Sorbic Acid ◽  
Collaborative Study ◽  
Thiobarbituric Acid ◽  
Volatile Acid ◽  
Wine Analysis ◽  
Red Color ◽  
532 Nm

Abstract A survey of a number of laboratories engaged in wine analysis showed that 2 basic techniques were used for the determination of sorbic acid. The first utilizes the absorbance by sorbic acid at 260 nm in acidic solution and the second depends on the oxidation of sorbic acid to malonaldehyde which is then reacted with thiobarbituric acid. The resulting red color is measured at 532 nm. A modification of the thiobarbituric method has been adopted by AOAC for the determination of sorbic acid in cheese. We found it could be successfully utilized for sorbic acid analysis in wine with minor changes. It was necessary to separate the sorbic acid from wine by steam distillation prior to either determination. The standard Cash wine volatile acid still is adequate for this purpose and over 9 9% acid could be recovered from a 2 ml wine sample in 200 ml distillate. We studied various parameters in both techniques and arrived at practical procedures for each. Both methods gave acceptable results and we recommend that they be subjected to a collaborative study.

Determination of Malonaldehyde as an Index of Rancidity in Nut Meats

1971 ◽  
Vol 54 (5) ◽  
pp. 1024-1026 ◽  
Author(s):  
David C Holland
Keyword(s):  
Acetic Acid ◽  
Acid Solution ◽  
Acetic Acid Solution ◽  
Meat Products ◽  
Thiobarbituric Acid ◽  
Taste Panel ◽  
Nacl Solution ◽  
Red Color ◽  
532 Nm

Abstract Distillation of ground walnut meats from a slightly acidified concentrated NaCl solution gives a high per cent recovery of malonaldehyde which is associated with rancidity in nut meat products. Heating an aliquot of the distillate in an acetic acid solution of 2-thiobarbituric acid yields an intense red color with a maximum absorbance at about 532 nm. As little as 0.1 μg malonaldehyde/ml can be measured. Nuts judged to be slightly rancid by a taste panel showed the presence of approximately 40 μg malonaldehyde/g nul meat. Recoveries of malonaldehyde added to samples ranged from 92 to 97%. No malonaldehyde was detected in fresh nut meats.

Collaborative Study of the Determination of Sorbic Acid in Wine

1975 ◽  
Vol 58 (1) ◽  
pp. 133-135
Author(s):  
Arthur Caputi ◽  
Karen Slinkard
Keyword(s):  
Sorbic Acid ◽  
Collaborative Study ◽  
Thiobarbituric Acid ◽  
The Other ◽  
Ultraviolet Spectrophotometry ◽  
Acid Complex ◽  
Average Recovery ◽  
Colorimetric Measurement ◽  
Coefficients Of Variation

Abstract Eleven collaborators participated in a study of 2 methods for determining sorbic acid in wine. One method utilizes ultraviolet spectrophotometry and the other depends on the colorimetric measurement of a thiobarbituric acid complex. Three different wine types were each spiked with 200, 300, and 400 mg sorbic acid/ L. Average recovery ranged from 97.3 to 107.5% with the thiobarbituric acid method with coefficients of variation from 4.4 to 8.7%. The ultraviolet method gave recoveries from 97 to 103.5% with coefficients of variation ranging from 2.0 to 6.4%. Comments on both methods from collaborators were favorable. Both methods have been adopted as official first action.

Determination of Benzoates and Hydroxybenzoates in Foods

1966 ◽  
Vol 49 (4) ◽  
pp. 829-834 ◽  
Author(s):  
Salvatore J Pinella ◽  
Anthony D Falco ◽  
George Schwartzman
Keyword(s):  
Benzoic Acid ◽  
Steam Distillation ◽  
Sorbic Acid ◽  
Collaborative Study ◽  
Qualitative And Quantitative ◽  
Recording Spectrophotometer ◽  
Chromatographic Plate ◽  
Steam Distillation Extraction ◽  
Tlc Separation

Abstract A method has been devised for the qualitative and quantitative determination of benzoates and hydroxybenzoates in foods. The qualitative procedure is based on the TLC separation of benzoic acid, the hydroxybenzoates, and sorbic acid, using kieselguhr G-silica gel GF 254 as the absorbent and hexane:acetic acid as the mobile solvent. The separated preserving acids are identified under UV radiation and by specific chromogenic reagents. Benzoic acid in foods was determined quantitatively by steam distillation, extraction, and TLC separation. The benzoic acid was removed from the chromatographic plate, extracted with ethanol, and determined in the UV region with a recording spectrophotometer and 5 cm micro cells. These procedures should be subjected to collaborative study.

Colorimetric Determination of Alkaline Phosphatase as Indicator of Mammalian Feces in Corn Meal: Collaborative Study

1986 ◽  
Vol 69 (3) ◽  
pp. 496-498
Author(s):  
Harriet Gerber ◽  
◽  
B Beavin ◽  
S Brown ◽  
J Bryce ◽  
...  
Keyword(s):  
Alkaline Phosphatase ◽  
Agar Medium ◽  
Collaborative Study ◽  
Official Method ◽  
Colorimetric Determination ◽  
Corn Meal ◽  
Small Particles ◽  
Red Color ◽  
Repeatability And Reproducibility

Abstract In the official method for rodent filth in corn meal, filth and corn meal are separated in organic solvents, and particles are identified by the presence of hair and a mucous coating. The solvents are toxic, poor separation yields low recoveries, and fecal characteristics are rarely present on all fragments, especially on small particles. The official AOAC alkaline phosphatase test for mammalian feces, 44.181-44.184, has therefore been adapted to determine the presence of mammalian feces in corn meal. The enzyme cleaves phosphate radicals from a test indicator/substrate, phenolphthalein diphosphate. As free phenolphthalein accumulates, a pink-to-red color develops in the gelled test agar medium. In a collaborative study conducted to compare the proposed method with the official method for corn meal, 44.049, the proposed method yielded 45.5% higher recoveries than the official method. Repeatability and reproducibility for the official method were roughly .1.8 times more variable than for the proposed method. The method has been adopted official first action.

Collaborative Study of the Determination of Ethanol in Wine by Chemical Oxidation

1969 ◽  
Vol 52 (1) ◽  
pp. 85-88 ◽  
Author(s):  
Arthur Caputi ◽  
Dawson Wright
Keyword(s):  
Steam Distillation ◽  
Potassium Dichromate ◽  
Collaborative Study ◽  
Sulfate Solution ◽  
Chemical Oxidation ◽  
Ferrous Ammonium Sulfate ◽  
Alcohol Content ◽  
Ferrous Ammonium ◽  
Better Than

Abstract A collaborative study was conducted on a chemical or dichromate oxidation procedure for etlianol in wine. The method is based on the steam distillation of ethanol from a 1 ml wine sample into an acidified solution of potassium dichromate, followed by heating 20 min at 60°C to complete the oxidation of the ethanol to acetic acid. The unreacted dichromate is determined by titration with a standard ferrous ammonium sulfate solution, using o-phenanthroline as an indicator. Eleven collaborators participated in the study, of whom seven were familiar with the method and four were not. Eight samples with alcohol content ranging from 11.8 to 23.5% by volume were analyzed. The standard deviations of the reported answers on the identical samples varied from 0.024 to 0.063% in the range of 11.8–20% ethanol and rose to 0,161% in the sample which contained 23.3% ethanol by volume. This reproducibility is better than has been reported with other commonly used methods, and it is recommended that the method be adopted as official first action.

Infrared Determination of Sorbic Acid in Foods

1965 ◽  
Vol 48 (4) ◽  
pp. 794-795
Author(s):  
George F Calloway ◽  
George Schwartzman
Keyword(s):  
Steam Distillation ◽  
Sorbic Acid ◽  
Collaborative Study ◽  
Food Product ◽  
Chloroform Extract ◽  
Food Samples ◽  
Infrared Method ◽  
Preliminary Study

Abstract Preliminary study of an infrared method for determination of sorbic acid in foods gave promising results. The procedure consists of steam distillation of the food product, extraction of the distillate with chloroform, and measurement of the infrared absorbance of the chloroform extract at 10 μ. Recoveries from 92 to 110% were obtained from 14 food samples spiked with 0.05–0.15% sorbic acid. A collaborative study is recommended.

Colorimetric Determination of Hydroxyproline as Measure of Collagen Content in Meat and Meat Products: NMKL Collaborative Study

1990 ◽  
Vol 73 (1) ◽  
pp. 54-57 ◽  
Author(s):  
Kurt Kolar
Keyword(s):  
Collaborative Study ◽  
Colorimetric Method ◽  
Meat Products ◽  
Acid Oxidation ◽  
Colorimetric Determination ◽  
Mean Values ◽  
Collaborative Studies ◽  
Freeze Dried ◽  
Analytical Result

Abstract A colorimetric method for the determination of hydroxyproline as a measure of collagen in meat and meat products has been collaboratively studied in 18 laboratories. The method includes hydrolysis with sulfuric acid, oxidation with chloramine- T, and formation of a reddish purple complex with 4- dimethylaminobenzaldehyde. Five frozen and 3 freeze-dried samples were tested, ranging in content from 0.11 to 0.88% and from 0.39 to 4.0% hydroxyproline, respectively. The mean values of 2 identical samples were 0.245 and 0.251 %. The average recovery from a spiked sample was 96.1 %. The hydroxyproline content of a known sample (a mixture of 2 samples in the ratio 5:2) was calculated to 1.42%, which agrees well with the analytical result, 1.40%. In comparison with other collaborative studies, based on the ISO analytical method, the repeatability and reproducibility of this method agree well with the other results. This method was accepted as an official NMKL method by all national Committees, and has been adopted official first action by AOAC as an NMKLAOAC method.

Colorimetric Determination of the Progestational Steroids in Contraceptive Tablets

1970 ◽  
Vol 53 (4) ◽  
pp. 831-833
Author(s):  
John Y P Wu
Keyword(s):  
Oral Contraceptive ◽  
Medroxyprogesterone Acetate ◽  
Collaborative Study ◽  
Chloroform Extract ◽  
Colorimetric Determination ◽  
Standard Deviations ◽  
Isonicotinyl Hydrazide ◽  
Norethindrone Acetate

Abstract Norethindrone, norethindrone acetate, dimethisterone, medroxyprogesterone acetate, and norethynodrel are determined in oral contraceptive tablets. For the first 4 compounds, a chloroform extract of the tablets is treated directly with isonicotinyl hydrazide reagent to produce a stable color which is measured at 380 nm. The chloroform extract of norethynodrel tablets is isomerized before the reagent is added. An intralaboratory study gave good results, with standard deviations of 0.74 to 1.21%. A collaborative study is recommended.

Determination of Hydroxybenzoates and Benzoates in Foods

1968 ◽  
Vol 51 (4) ◽  
pp. 876-877
Author(s):  
M H Lewis
Keyword(s):  
Quantitative Determination ◽  
Steam Distillation ◽  
Uv Spectroscopy ◽  
Collaborative Study ◽  
Solid Foods

Abstract A successful collaborative study was made on the determination of benzoates in solid foods, using the official, first action method for benzoates in liquid and semisolid foods. The method combines steam distillation, TLC, and UV spectroscopy. Recovery data ranged from 94 to 120%. An attempt to separate the parabens by GLC was successful but further work is needed for the quantitative determination of these compounds.

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