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.

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.

Collaborative Study of Accuracy and Precision of Rapid Determination of Fat in Meat and Meat Products by Foss-Let Method

1977 ◽  
Vol 60 (4) ◽  
pp. 853-858 ◽  
Author(s):  
Julio D Pettinati ◽  
Clifton E Swift
Keyword(s):  
Food Industry ◽  
Rapid Determination ◽  
Collaborative Study ◽  
Meat Products ◽  
T Test ◽  
Laboratory Sample ◽  
Accuracy And Precision ◽  
Aoac Method ◽  
Better Than

Abstract Collaborators in 12 meat and food industry laboratories performed 4 fat determinations each on 7 samples of meat and meat products by the rapid (7–10 min) Foss-Let method and compared the results with those obtained by AOAC method 24.005(a) or 24.005(b). From the overall mean of results on all samples, determinations by the Foss-Let method averaged 0.11% fat higher than by the AOAC method. This difference was not significant by the t-test (P = 0.05), which indicated agreement between the compared methods in determining fat content. Precision of the Foss-Let method was equivalent to and generally slightly better than that of the AOAC method. Standard deviations with the Foss-Let method were 0.2 % fat for between-duplicates and for within-laboratory repeatability; 0.4% fat for between-laboratories, including variation due to laboratory-sample interaction; and 0.5% fat for reproducibility between analysts in different laboratories. The Foss-Let method has been adopted as official first action.

Comparison of Two Methods for Determination of Total Solids Content of Milk: Collaborative Study

1989 ◽  
Vol 72 (5) ◽  
pp. 712-718 ◽  
Author(s):  
Jenny L Clark ◽  
David M Barbano ◽  
Chapman E Dunham
Keyword(s):  
Collaborative Study ◽  
Raw Milk ◽  
Preliminary Evaluation ◽  
Oven Method ◽  
Total Solids ◽  
Relative Standard ◽  
Aoac Method ◽  
Standard Deviations ◽  
Forced Air ◽  
Solids Content

Abstract Ten laboratories analyzed 9 pairs of blind duplicate raw milk samples for total solids. A direct forced air oven method (4 h at 100°C) and a modification of the AOAC predry method (16.032) were used. Preliminary evaluation of the modified AOAC method indicated that blank determinations were necessary. Total solids content ranged from 12.0 to 14.6%. Average repeatability standard deviations (sr) of the direct forced air oven and modified AOAC methods were 0.019 and 0.017, respectively. Average reproducibility standard deviations (SR) of the direct forced air oven and the modified AOAC methods were 0.042 and 0.047, respectively. Average repeatability relative standard deviations (RSDr) for the direct forced air oven and the modified AOAC methods were 0.149 and 0.136%, respectively; average reproducibility relative standard deviations (RSDR) were 0.327 and 0.370%, respectively. Mean repeatability values (r) and reproducibility values (R) were 0,054 and 0.118 for the direct forced air oven method and 0.049 and 6.133 for the modified AOAC method, respectively. The mean test result of the direct forced air oven method (12.7293%) was comparable to that for the modified AOAC method (12.7273%). The modification of AOAC method 16.032 and the direct forced air oven method have been approved interim official first action.

Collaborative Study of the Determination of Phosphorus in Gelatin, Dessert Preparations, and Mixes

1972 ◽  
Vol 55 (3) ◽  
pp. 581-582
Author(s):  
Roger G Burkepile
Keyword(s):  
Collaborative Study ◽  
Official Method ◽  
Standard Samples ◽  
Preliminary Work ◽  
Aoac Method ◽  
Standard Deviations

Abstract A collaborative study of the proposed method for phosphorus in gelatin, dessert preparations, and mixes has been conducted. The present AOAC method for phosphorus in fertilizers, 2.023–2.025(a), was modified for this study. Preliminary work by the Associate Referee involving 4 phosphorus standard samples compared the proposed method with the official final action AOAC method for gelatin, 23.004. Additionally, phosphorus standard spikes in gelatin at the 1 and 10 mg P2O5, levels were determined by the proposed method. The proposed method is faster and more sensitive than the official method and is as accurate. Five collaborators and the Associate Referee analyzed 4 prepared samples containing various levels of phosphorus by the proposed method. The standard deviations varied from 0.005 for a 225 Bloom gelatin containing an average of 0.273% P2O5 to 0.016 for a strawberry-flavored commercial gelatin with added lecithin containing an average of 0.110% P2O5. The proposed method has been adopted as official first action to replace 23.004, which was repealed, official first action.

Fluorometric Determination of Alkaline Phosphatase in Fluid Dairy Products: Collaborative Study

1990 ◽  
Vol 73 (6) ◽  
pp. 842-849 ◽  
Author(s):  
Richard M Rocco
Keyword(s):  
Alkaline Phosphatase ◽  
Dairy Products ◽  
Collaborative Study ◽  
Skim Milk ◽  
Raw Milk ◽  
Chocolate Milk ◽  
Phenyl Phosphate ◽  
Whole Milk ◽  
Standard Deviations

Abstract Official methods for the measurement of alkaline phosphatase (ALP) in dairy products use either phenyl phosphate or phenolphthaleln monophosphate as substrate. Quantitation of results requires butanol extraction of the Indophenol (Scharer) or 3-h dialysis of the liberated phenolphthaleln (Rutgers). The Advanced Fluorophos® assay Is based on a self-indicating substrate which, when acted upon by ALP, loses a phosphate radical and becomes a highly fluorescent compound. The rate of fluorophore formation Is monitored for 3 mln In a fluorometer and the enzyme activity In mU/L Is calculated. Eight laboratories participated in a collaborative study to evaluate the Fluorophos® assay for determining ALP activity In whole milk, skim milk, chocolate milk, and cream (half and half). The comparative method was the AOAC quantitative phenyl phosphate method, 16.121-16.122 (14th Ed.). Mixed herd raw milk was added to pasteurized samples at 0.05, 0.1, and 0.2% (v/v). Method performance at 0.1% (v/v) added raw milk as measured by repeatability and reproducibility standard deviations (sr and sR) and relative standard deviations (RSDr and RSDR), respectively, were: whole milk, sr = 21.7%, sR = 34.6%, RSDr = 4.4%, RSDR = 7.0%; skim milk, sr = 19.2%, sR = 31.4%, RSDr = 3.8%, RSDR = 6.2%; chocolate milk, sr = 27.6%, sR = 45.8%, RSDr = 5.3%, RSDR = 8.8%. The method has been adopted official first action by AOAC for determination of alkaline phosphatase in whole milk, skim milk, and chocolate milk.

scholarly journals Determination of Total Dietary Fiber in Selected Foods Containing Resistant Maltodextrin by Enzymatic-Gravimetric Method and Liquid Chromatography: Collaborative Study

2002 ◽  
Vol 85 (2) ◽  
pp. 435-444 ◽  
Author(s):  
Dennis T Gordon ◽  
Kazuhiro Okuma ◽  
J W DeVries ◽  
K Fukuhara ◽  
W Jacob ◽  
...  
Keyword(s):  
Liquid Chromatography ◽  
Dietary Fiber ◽  
Average Molecular Weight ◽  
Collaborative Study ◽  
Gravimetric Method ◽  
Soluble Dietary Fiber ◽  
Total Dietary Fiber ◽  
Resistant Maltodextrin ◽  
Standard Deviations

Abstract A method was developed for determination of total dietary fiber (TDF) in foods containing resistant maltodextrin (RMD) which includes nondigestible carbohydrates that are not fully recovered as dietary fiber by conventional TDF methods such as AOAC 985.29 or 991.43. Because the average molecular weight (MW) of RMD is 2000 daltons, lower MW soluble dietary fiber components do not precipitate in 78% ethanol; therefore, RMD is not completely quantitated as dietary fiber by current AOAC methods. The accuracy and precision of the method was evaluated through an AOAC collaborative study. Ten laboratories participated and assayed 12 test portions (6 blind duplicates) containing RMD. The 6 test pairs ranged from 1.5 to 100% RMD. The method consisted of the following steps: (1) The insoluble dietary fiber (IDF) and high MW soluble dietary fiber (HMWSDF) were determined by AOAC 985.29. (2) Ion exchange resins were used to remove salts and proteins contained in the AOAC 985.29 filtrates (including ethanol and acetone). (3) The amount of low MWRMD (LMWRMD) in the filtrates were determined by liquid chromatography. (4) The TDF was calculated by summation of the IDF, HMWSDF, and LMWRMD fractions having nondigestible carbohydrates with a degree of polymerization of 3 and higher. Repeatability standard deviations (RSDr) were 1.33–7.46%, calculated by including outliers, and 1.33–6.10%, calculated by not including outliers. Reproducibility standard deviations (RSDR) were 2.48–9.39%, calculated by including outliers, and 1.79–9.39%, calculated by not including outliers. This method is recommended for adoption as Official First Action.

scholarly journals Total Dietary Fiber (CODEX Definition) in Foods and Food Ingredients by a Rapid Enzymatic-Gravimetric Method and Liquid Chromatography: Collaborative Study, First Action 2017.16

2019 ◽  
Vol 102 (1) ◽  
pp. 196-207 ◽  
Author(s):  
Barry V McCleary ◽  
N Ames ◽  
J Cox ◽  
S Iilians ◽  
Y Jin ◽  
...  
Keyword(s):  
Dietary Fiber ◽  
Collaborative Study ◽  
Gravimetric Method ◽  
Soluble Dietary Fiber ◽  
Total Dietary Fiber ◽  
Plant Materials ◽  
Food Ingredients ◽  
Insoluble Dietary Fiber ◽  
The Past ◽  
Aoac Method

Abstract A method for measurement of total dietary fiber (TDF) has been validated. This method is applicable to plant materials, foods, and food ingredients as consumed, consistent with the 2009 CODEX definition (ALINORM 09/32/REP), and measures insoluble dietary fiber (IDF) and soluble dietary fiber (SDF), comprising SDF that precipitates in the presence of 78% ethanol (SDFP) and SDF that remains soluble in the presence of 78% ethanol (SDFS). The method is an update of AOAC Method 2009.01 and addresses each of the issues identified by analysts in using that method over the past 8 years. A total of 13 laboratories participated in the study, with all laboratories returning valid assay data for most of the 16 test portions (8 blind duplicates) consisting of samples with a range of content of traditional dietary fibers, resistant starch, and nondigestible oligosaccharides. The dietary fiber content of the eight test pairs ranged from 6.90 to 60.37 g/100 g. TDF was calculated as the sum of IDF plus SDFP measured gravimetrically and SDFS measured by HPLC. The repeatability SD ranged from 0.27 to 0.76 g/100 g, and the reproducibility SD ranged from 0.54 to 3.99 g/100 g. The RSDr ranged from 1.22 to 6.52%, and the RSDR ranged from 2.14 to 10.62%.

Collaborative Study of the Photometric Molyb do vanadate Method for Phosphorus

1965 ◽  
Vol 48 (3) ◽  
pp. 654-657
Author(s):  
Mary Heckman
Keyword(s):  
Collaborative Study ◽  
Gravimetric Method ◽  
Volumetric Method ◽  
Photometric Method ◽  
Coefficients Of Variation ◽  
Standard Deviations ◽  
Official Status ◽  
Feed Samples ◽  
Phosphorus Levels ◽  
Good Agreement

Abstract Sixteen laboratories analyzed five feed samples, with phosphorus levels ranging from about 0.60 to 5.50% by the photometric molybdovanadate method studied in 1963 (This Journal, 46, 836 (1963)), and by either the volumetric method, 22.061, or the gravimetric quinoline molybdate method (ibid., 47, 170 (1964)), both of which have some official status. Eight sets of results based on the volumetric method and eight based on the gravimetric method were available. Means for all methods were in good agreement. Standard deviations and coefficients of variation were satisfactory for all methods, indicating superiority of both volumetric and gravimetric methods over the photometric method. Calculation of standard deviations for the entire range tested, however, showed the photometric method to be superior to the volumetric method and inferior to the gravimetric. The molybdovanadate method was adopted as official, first action.

scholarly journals Determination of Retinyl Palmitate (Vitamin A) in Fortified Fluid Milk by Liquid Chromatography: Collaborative Study

2003 ◽  
Vol 86 (2) ◽  
pp. 375-385 ◽  
Author(s):  
Douglas A Hite ◽  
L Angelo ◽  
S Bhandari ◽  
S Bhattacharyya ◽  
E Bonnin ◽  
...  
Keyword(s):  
Vitamin A ◽  
Milk Fat ◽  
Collaborative Study ◽  
Skim Milk ◽  
Internal Standard ◽  
Retinyl Palmitate ◽  
Test Portion ◽  
Standard Deviations ◽  
Fluid Milk

Abstract A liquid chromatographic (LC) method was developed for fast and simple measurement of retinyl palmitate (vitamin A) in fortified milk. Retinyl acetate internal standard was added to a test portion of milk followed by extraction into hexane. The hexane extract was analyzed by LC using a normal-phase silica gel column equilibrated with mobile phase (conditioned hexane–isopropanol, 99.85 + 0.15, v/v) about 1 h before injections. The retinyl palmitate concentration was calculated by using a relative response factor determined with calibration standards. In the collaborative study, 11 laboratories analyzed 13 pairs of fluid milk materials in blind duplicate. Twelve of the materials were composed of skim milk (<0.5% fat), 1% fat milk, 2% fat milk, and 1% fat chocolate milk. Each material was fortified at 3 concentrations of retinyl palmitate of approximately 581 μg/L (1000 IU/qt), 1163 μg/L (2000 IU/qt), and 2236 μg/L (4000 IU/qt). The 13th material, unfortified skim milk, served as a matrix blank. Repeatability standard deviations (RSDr) without outliers ranged from 1.5 to 5.7% and reproducibility standard deviations (RSDR) without outliers ranged from 5.0 to 22.7%. cis-Isomers co-eluted with the predominant trans-retinyl palmitate isomer and were included in the results reported by all the collaborative laboratories. Endogenous long-chain esters from milk fat were also measured with the retinyl palmitate additive. The Study Director recommends that this method for determination of retinyl palmitate in fluid milk by LC be adopted First Action.

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.

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