Collaborative Study of Methods for the Determination of Chloride, Citrate, and Phosphate in Processed Cheese

1976 ◽  
Vol 59 (5) ◽  
pp. 1142-1145
Author(s):  
Henry R Brzenk ◽  
O Joseph Krett
Keyword(s):  
Collaborative Study ◽  
Gravimetric Method ◽  
Error Component ◽  
International Organization ◽  
Processed Cheese ◽  
International Organization For Standardization ◽  
Laboratory Error ◽  
Aoac Method ◽  
International Dairy Federation

Abstract A collaborative study was conducted to compare the International Dairy Federation (IDF)/International Organization for Standardization (ISO)/Association of Official Analytical Chemists (AOAC) proposed methods for the determination of chloride and citrate in processed cheese with the corresponding current AOAC methods. Since there is no current AOAC method for phosphate, only the IDF/ISO/AOAC method was used. Five samples of processed cheese were prepared with varying added amounts of the anions of interest. The samples were analyzed in duplicate by 7 collaborating laboratories. For chloride, both methods are comparable, but since the IDF/ISO/AOAC method is simpler and faster it has been adopted as official first action to replace the current AOAC method, 16.224. For citrate, the colorimetric IDF/ISO/AOAC method is more rapid and simpler than the current AOAC gravimetric method. However, the AOAC method is more precise. Therefore, the proposed method has been adopted as official first action as an alternative to 16.237. For phosphate, 2 of the 7 laboratories were outliers by the Youden ranking test but the results by the remaining laboratories appear satisfactory. The phosphate method should receive further study to reduce the between-laboratory error component.

scholarly journals Determination of Total Dietary Fiber (CODEX Definition) by Enzymatic-Gravimetric Method and Liquid Chromatography: Collaborative Study

2010 ◽  
Vol 93 (1) ◽  
pp. 221-233 ◽  
Author(s):  
Barry V McCleary ◽  
Jonathan W De Vries ◽  
Jeanne I Rader ◽  
Gerald Cohen ◽  
Leon Prosky ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Dietary Fiber ◽  
Resistant Starch ◽  
Collaborative Study ◽  
Gravimetric Method ◽  
Low Molecular Weight ◽  
Total Dietary Fiber ◽  
Aoac Method ◽  
Standard Deviations

Abstract A method for the determination of total dietary fiber (TDF), as defined by the CODEX Alimentarius, was validated in foods. Based upon the principles of AOAC Official MethodsSM 985.29, 991.43, 2001.03, and 2002.02, the method quantitates high- and low-molecular-weight dietary fiber (HMWDF and LMWDF, respectively). In 2007, McCleary described a method of extended enzymatic digestion at 37C to simulate human intestinal digestion followed by gravimetric isolation and quantitation of HMWDF and the use of LC to quantitate low-molecular-weight soluble dietary fiber (LMWSDF). The method thus quantitates the complete range of dietary fiber components from resistant starch (by utilizing the digestion conditions of AOAC Method 2002.02) to digestion resistant oligosaccharides (by incorporating the deionization and LC procedures of AOAC Method 2001.03). The method was evaluated through an AOAC collaborative study. Eighteen laboratories participated with 16 laboratories returning valid assay data for 16 test portions (eight blind duplicates) consisting of samples with a range of traditional dietary fiber, resistant starch, and nondigestible oligosaccharides. The dietary fiber content of the eight test pairs ranged from 11.57 to 47.83. Digestion of samples under the conditions of AOAC Method 2002.02 followed by the isolation and gravimetric procedures of AOAC Methods 985.29 and 991.43 results in quantitation of HMWDF. The filtrate from the quantitation of HMWDF is concentrated, deionized, concentrated again, and analyzed by LC to determine the LMWSDF, i.e., all nondigestible oligosaccharides of degree of polymerization 3. TDF is calculated as the sum of HMWDF and LMWSDF. Repeatability standard deviations (sr) ranged from 0.41 to 1.43, and reproducibility standard deviations (sR) ranged from 1.18 to 5.44. These results are comparable to other official dietary fiber methods, and the method is recommended for adoption as Official First Action.

Vacuum Desiccation Methods for Determination of Free Water in Fertilizers: Interlaboratory Comparison

1980 ◽  
Vol 63 (3) ◽  
pp. 554-555
Author(s):  
Russell D Duncan ◽  
◽  
C H McBride ◽  
E J Hube ◽  
P Kane ◽  
...  
Keyword(s):  
Interlaboratory Comparison ◽  
Free Water ◽  
International Organization ◽  
International Organization For Standardization ◽  
Aoac Method

Abstract A vacuum desiccation method for determining free water in fertilizer, proposed by the International Organization for Standardization (ISO), was compared to the official AOAC vacuum desiccation method (2.013). The combined results of 4 U.S. laboratories showed, on the basis of 5 samples, that precision was better by the ISO method, but results were lower for 4 of the 5 samples. The AOAC method gave a slightly lower result for one sample.

Collaborative Study of the Gravimetric Method for the Determination of Mercury in Chlorinated Pesticide Formulations

1975 ◽  
Vol 58 (1) ◽  
pp. 33-34
Author(s):  
James E Launer
Keyword(s):  
Collaborative Study ◽  
Gravimetric Method ◽  
Chlorinated Pesticides ◽  
Titrimetric Method ◽  
Pesticide Formulations ◽  
Aoac Method

Abstract The official first action AOAC gravimetric method for mercury, 6.C01–6.C03, and the official CIPAC titrimetric method, M2.3, were collaboratively studied by 4 CIPAC laboratories, using the same 4 samples analyzed by AOAC collaboration in 1972. Averages at the 3.7 and 3.4% level were the same by both methods whereas the CIPAC method produced, on the average, 4% higher results, all levels included. The AOAC method performs well in the presence of copper and chlorinated pesticides and is less complex to use than the present CIPAC method for mercury in these mixtures. The method has been adopted as official final action.

Ruggedness Test for Ashing Methods in Feed: Comparison of Proposed Method of the International Organization for Standardization with AOAC Method

1977 ◽  
Vol 60 (4) ◽  
pp. 842-844
Author(s):  
Laszlo Torma
Keyword(s):  
Mineral Content ◽  
Statistical Evaluation ◽  
International Organization ◽  
Test Portion ◽  
International Organization For Standardization ◽  
Three Samples ◽  
Aoac Method ◽  
Time Required

Abstract A Youden ruggedness test was performed on the determination of ash in feeds to compare the proposed method of the International Organization for Standardization (ISO) with the official AOAC method. Three samples which contained low, medium, and high ash were analyzed. Six variables were studied : material of the ashing dishes, test portion, preliminary ashing, ashing temperature, ashing time, and additional ashing. Statistical evaluation of the ruggedness test indicated that for Sample A (5.41% average ash), the factors under study did not influence the ash recovery; for Sample B (10.84% average ash), changes in temperature influenced the ash recovery; and for Sample C (13.97% average ash), changes in preliminary ashing, temperature, and additional ashing appeared to influence the ash recovery. It is recommended that the composition of ash be studied further in order to evaluate the temperature and ashing time required to determine nutritionally valuable mineral content.

Flour Acidity Comparisons as Related to Fat Acidity Methods of the Association of Official Analytical Chemists and the International Organization for Standardization

1990 ◽  
Vol 73 (4) ◽  
pp. 626-627
Author(s):  
Gregory D Parker ◽  
Ralph H Lane
Keyword(s):  
Petroleum Ether ◽  
Petroleum Ether Extract ◽  
Collaborative Study ◽  
International Organization ◽  
Official Method ◽  
Whole Wheat Flour ◽  
International Organization For Standardization ◽  
Whole Wheat ◽  
Aoac Method ◽  
Flour Sample

Abstract Acidity data were compared of selected flour samples obtained by methods of the International Organization for Standardization (ISO) and the Association of Official Analytical Chemists (AOAC) with and without toluene as a part of the titration medium. In all cases, the ISO method produced significantly higher fat acidity values (P < 0.001) than the AOAC method, probably as a result of greater extraction of acidic materials with the more polar solvent, 95% alcohol, than with petroleum ether. Except for a whole wheat flour sample, no differences (P > 0.05) existed between fat acidity values produced by AOAC methodology consisting of titration of the evaporated petroleum ether extract of the flour in a medium of equal volumes of 95% alcohol and toluene as prescribed In the official method (14.069-14.071), or In a medium of 95% alcohol alone. Based on the data and the potential toxicity of toluene, a collaborative study Is recommended to determine the Influence of Its removal from the official AOAC method. Fat

scholarly journals Determination of the Total Nitrogen Content of Hard, Semihard, and Processed Cheese by the Kjeldahl Method: Collaborative Study

2002 ◽  
Vol 85 (2) ◽  
pp. 445-455 ◽  
Author(s):  
Joanna M Lynch ◽  
David M Barbano ◽  
J Richard Fleming ◽  
◽  
◽  
...  
Keyword(s):  
Standard Deviation ◽  
Nitrogen Content ◽  
Relative Standard Deviation ◽  
Total Nitrogen ◽  
Crude Protein ◽  
Collaborative Study ◽  
Processed Cheese ◽  
Relative Standard ◽  
Aoac Method

Abstract The objective of this collaborative study was to determine interlaboratory performance statistics for a modified and optimized version of AOAC Method 920.123 for the determination of the total nitrogen content of hard, semihard, and processed cheese by Kjeldahl analysis. Details included addressing the issues of material homogeneity, test portion size (1 g), quantitative transfer (weighing on to filter paper), ensuring system suitability (nitrogen recoveries), and using AOAC Method 991.20 as the basis for nitrogen analysis. Fifteen laboratories tested 18 pairs of blind duplicate cheese materials with a crude protein content between 18 and 36%. Materials represented hard, semihard, and processed commercial cheeses with a wide range of composition. Statistical performance parameters expressed as crude protein (nitrogen × 6.38), g/100 g, with invalid and outlier data removed were mean = 26.461, repeatability standard deviation (Sr) = 0.111, reproducibility standard deviation (SR) = 0.153, repeatability relative standard deviation (RSDr) = 0.42%, reproducibility relative standard deviation (RSDR) = 0.58%, repeatability (r) = 0.312, and reproducibility (R) = 0.428. The interlaboratory study results were acceptable and comparable to those for the milk Kjeldahl nitrogen method on a relative nitrogen basis. The Study Directors recommend that this modified method for the determination of total nitrogen in hard, semihard, and processed cheese by Kjeldahl analysis be adopted First Action as an improved method to replace Method 920.123.

Enzymatic-Ultraviolet Method for Measuring Lactose in Milk: Collaborative Study

1984 ◽  
Vol 67 (3) ◽  
pp. 637-640 ◽  
Author(s):  
David O Biltcliffe ◽  
Dick H Kleyn ◽  
J Richard Trout ◽  
◽  
D Azzara ◽  
...  
Keyword(s):  
Food Industry ◽  
Collaborative Study ◽  
Skim Milk ◽  
Gravimetric Method ◽  
T Test ◽  
Enzymatic Method ◽  
Commercial Laboratory ◽  
Aoac Method ◽  
Standard Deviations

Abstract Collaborators in 8 dairy and food industry laboratories performed one lactose determination on each of 8 unknown samples of milk, lowfat milk, or skim milk, as 3 pairs of blind duplicates. Two known samples were provided to gain experience prior to analysis of the unknown samples. All of the above samples were also analyzed for lactose content by the official AOAC gravimetric method (16.507) by a commercial laboratory. From the overall mean of results on all samples, determinations by the enzymatic method averaged 0.49% lower than by the AOAC method. This difference was significant by the t-test (P = 0.05), which indicated a lack of agreement between the compared methods in determining lactose content. Standard deviations were similar for the 3 sets of blind duplicates which ranged between 3.67 and 4.55% lactose content. F-values revealed that variations between means obtained by laboratories differed significantly as compared with variations within laboratory means. The method has been adopted official first action.

Determination of Total, Soluble, and Insoluble Dietary Fiber in Foods—Enzymatic-Gravimetric Method, MES-TRIS Buffer: Collaborative Study

1992 ◽  
Vol 75 (3) ◽  
pp. 395-416 ◽  
Author(s):  
Sungsoo C Lee ◽  
Leon Prosky ◽  
Jonathan W De Vries
Keyword(s):  
Dietary Fiber ◽  
Collaborative Study ◽  
Gravimetric Method ◽  
Tris Buffer ◽  
Total Dietary Fiber ◽  
Method Performance ◽  
Insoluble Dietary Fiber ◽  
Heat Stable ◽  
Assay Precision

Abstract A joint AOAC/AACC (American Association of Cereal Chemists) collaborative study of methods for the determination of soluble, insoluble, and total dietary fiber (SDF, IDF, and TDF) was conducted with 11 participating laboratories. The assay Is based on a modification of the AOAC TDF method 985.29 and the SDF/IDF method collaboratively studied recently by AOAC. The principles of the method are the same as those for the AOAC dietary fiber methods 985.29 and 991.42, Including the use of the same 3 enzymes (heat-stable α-amylase, protease, and amyloglucosldase) and similar enzyme Incubation conditions. In the modification, minor changes have been made to reduce analysis time and to Improve assay precision: (1) MES-TRIS buffer replaces phosphate buffer; (2) one pH adjustment step Is eliminated; and (3) total volumes of reaction mixture and filtration are reduced. Eleven collaborators were sent 20 analytical samples (4 cereal and grain products, 3 fruits, and 3 vegetables) for duplicate blind analysis. The SDF, IDF, and TDF content of the foods tested ranged from 0.53 to 7.17, 0.59 to 60.53, and 1.12 to 67.56 g/100 g, respectively. The respective average RSDR values for SDF, IDF, and TDF determinations by direct measurements were 13.1, 5.2, and 4.5%. The TDF values calculated by summing SDF and IDF were in excellent agreement with the TDF values measured independently. The modification did not alter the method performance with regard to mean dietary fiber values, yet It generated lower assay variability compared with the unmodified methods. The method for SDF, IDF, and TDF (by summing SDF and IDF) has been adopted first action by AOAC International.

Comparison of Methods for Determining Biuret in Urea

1979 ◽  
Vol 62 (1) ◽  
pp. 153-159
Author(s):  
Luis F Corominas ◽  
Victor M Boy ◽  
Manuel Guijosa
Keyword(s):  
Atomic Absorption ◽  
Spectrophotometric Determination ◽  
Atomic Absorption Spectrophotometry ◽  
International Organization ◽  
Comparison Of Methods ◽  
Definite Advantage ◽  
Absorption Spectrophotometry ◽  
Alternative Procedures ◽  
Aoac Method

Abstract The official first action AOAC method for the spectrophotometric determination of biuret in urea, 2.072—2.074, was compared with official first action AOAC method 2.C01-2.C03 (atomic absorption spectrophotometry), 2 simplified versions of 2.072-2.074, and modified versions of 2 alternative procedures of the International Organization for Standardization. Three synthetic urea samples (0.3, 1.4, and 3.0% biuret) and 1 commercial urea sample (1.0% biuret) were analyzed. The methods proved to be equivalent and none showed a definite advantage over 2.072-2.074. The purification of biuret and the interference by ammonia are also discussed.

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