Enzyme Immunoassay for Determination of Gluten in Foods: Collaborative Study

1991 ◽  
Vol 74 (2) ◽  
pp. 257-264 ◽  
Author(s):  
John H Skerritt ◽  
Amanda S Hill
Keyword(s):  
Enzyme Immunoassay ◽  
Collaborative Study ◽  
Wheat Gluten ◽  
Meat Products ◽  
Processed Meat ◽  
Cereal Products ◽  
Relative Standard ◽  
Cooked Meats ◽  
Wheat Flours

Abstract A collaborative study was performed In 15 laboratories to validate a monoclonal antibody-based enzyme Immunoassay (EIA) for determination of gluten in foods. The study Included 13 samples: maize starch, "gluten-free" baking mixes, wheat flours, cookies, cooked meats, and a soup. Gluten was present In these samples at either zero or 0.02 to 10% by weight, I.e., over almost 3 orders of magnitude. The mean assay values for the foods varied from 88 to 105% of the actual amounts. The assay was quantitative for cereal products and the soup with repeatability (RSDr, relative standard deviation) and reproducibility (RSDR) of 16-22% and 24-33%, respectively. The assay was semiquantitative for the processed meat products (RSDr 14 and 26% and RSDr 46 and 56%), probably because gluten was unevenly distributed In the small (1 g) samples that were analyzed. The ELISA method produced no false positive results, and false negatives obtained with tannin-containing foods could be avoided by use of a modified sample extractant. None of the collaborators reported problems In following the protocol. The method has been adopted official first action by AOAC for determination of wheat gluten in foods.

Sulfuric Acid/Hydrogen Peroxide Digestion and Colorimetric Determination of Phosphorus in Meat and Meat Products: Collaborative Study

1991 ◽  
Vol 74 (1) ◽  
pp. 22-26 ◽  
Author(s):  
David K Christians ◽  
Thomas G Aspelund ◽  
Scott V Brayton ◽  
Larry L Roberts
Keyword(s):  
Hydrogen Peroxide ◽  
Sulfuric Acid ◽  
Collaborative Study ◽  
Meat Products ◽  
Colorimetric Determination ◽  
Pork Sausage ◽  
Relative Standard ◽  
Significant Difference ◽  
Standard Deviations

Abstract Seven laboratories participated In a collaborative study of a method for determination of phosphorus in meat and meat products. Samples are digested In sulfuric acid and hydrogen peroxide; digestion Is complete In approximately 10 mln. Phosphorus Is determined by colorimetric analysis of a dilute aliquot of the sample digest. The collaborators analyzed 3 sets of blind duplicate samples from each of 6 classes of meat (U.S. Department of Agriculture classifications): smoked ham, water-added ham, canned ham, pork sausage, cooked sausage, and hamburger. The calibration curve was linear over the range of standard solutions prepared (phosphorus levels from 0.05 to 1.00%); levels in the collaborative study samples ranged from 0.10 to 0.30%. Standard deviations for repeatability (sr) and reproducibility (sR) ranged from 0.004 to 0.012 and 0.007 to 0.014, respectively. Corresponding relative standard deviations (RSDr and RSDR, respectively) ranged from 1.70 to 7.28% and 3.50 to 9.87%. Six laboratories analyzed samples by both the proposed method and AOAC method 24.016 (14th Ed.). One laboratory reported results by the proposed method only. Statistical evaluations Indicated no significant difference between the 2 methods. The method has been adopted official first action by AOAC.

scholarly journals Method for the Rapid Determination of Protein in Meats Using the CEM Sprint™ Protein Analyzer: Collaborative Study

2011 ◽  
Vol 94 (5) ◽  
pp. 1555-1561
Author(s):  
Cindy Moser ◽  
Kathy Herman ◽  
K Barnhardt ◽  
M Ceizyk ◽  
T Chriscoe ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Relative Standard Deviation ◽  
Rapid Determination ◽  
Collaborative Study ◽  
Meat Products ◽  
The United States ◽  
Processed Meat ◽  
Binding Agent ◽  
Relative Standard ◽  
Dye Binding

Abstract A collaborative study was conducted to determine the protein content of raw and processed meat products by a protein-tagging and colorimetric technique. Meat products were prepared following AOAC Official MethodSM 983.18 and analyzed using CEM Corporation's Sprint Rapid Protein Analyzer. Sprint provides protein results by combining an accurately weighed test portion with a known amount of dye-binding agent. The dye-binding agent binds with the lysine, histidine, and arginine, as well as the n-terminus of the proteins commonly found in raw meat and processed meat products. Results are displayed and reported by the Sprint as a percentage (g/100 g) of protein. Ten blind duplicate study samples were sent to 10 collaborating laboratories in the United States. The within-laboratory (repeatability) relative standard deviation (RSDr) ranged from 0.91 to 3.04%, and between-laboratories (reproducibility) relative standard deviation (RSDR) ranged from 1.50 to 3.41% for protein. The method is recommended for Official First Action.

scholarly journals Determination of Moisture and Fat in Meats by Microwave and Nuclear Magnetic Resonance Analysis: Collaborative Study

2008 ◽  
Vol 91 (4) ◽  
pp. 802-810 ◽  
Author(s):  
Timothy P Leffler ◽  
Cindy R Moser ◽  
Bobbie J McManus ◽  
John J Urh ◽  
Jimmy T Keeton ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Collaborative Study ◽  
Meat Products ◽  
Fat Content ◽  
Microwave Drying ◽  
Processed Meat ◽  
Nmr Spectrometry ◽  
Relative Standard ◽  
Aoac Method ◽  
Total Fat

Abstract Ten laboratories participated in a collaborative study to determine the total moisture and fat in raw and processed meat products by microwave drying and nuclear magnetic resonance (NMR) spectroscopy. Meat products were prepared following the AOAC Method and analyzed using CEM Corp.'s SMART Trac Moisture and Fat Analysis system. SMART Trac provides moisture results by measuring the weight loss on drying by microwave energy. The dried sample is then analyzed by NMR spectrometry for fat content. Moisture and fat results are displayed and reported by the SMART Trac as a percentage (g/100 g). Microwave drying is an AOAC-approved reference method (Method 985.14), Moisture in Meat and Poultry Products. NMR spectrometry is a secondary technique used to determine the concentration of various constituents in biological, organic, or chemical samples. The study design was based on Youden's matched pair principle for collaborative tests. For the purposes of this study, 10 laboratories each tested 10 Youden matched pairs, for a total of 20 samples. The study samples represented a range of products processed daily in plant operations. Included were raw meat samples (beef, pork, chicken, and turkey) as well as processed meats (beef hot dog, pork sausage, and ham). The total moisture content of the undiluted samples, as received for the purposes of this study, was determined by AOAC Method 950.46 and ranged from 54.03 to 74.99. The total fat content of the undiluted samples was determined by AOAC Method 960.39 and ranged from 1.00 to 29.79. Statistical analysis of study results for total moisture yielded a relative standard deviation for repeatability (RSDr) range of 0.14 to 0.95 and a relative standard deviation for reproducibility (RSDR) range of 0.26 to 0.95. Statistical analysis for total fat yielded similar RSDr and RSDR range of 0.74 to 4.08. Results for turkey had higher RSDr and RSDR values, both at 12.6, due to low fat content and possibly to the separation of the samples observed by some of the collaborators. Results demonstrate that microwave drying with NMR is a rapid, practical method providing results equivalent to AOAC Methods 950.46 (Forced Air Oven Drying) and 960.39 (Soxhlet Ether Extraction) in raw and processed meat products.

Enzymatic Determination of Free Glutamic Acid in Dried Soups and in Minced Sausages: NMKL1 Collaborative Study

1991 ◽  
Vol 74 (6) ◽  
pp. 921-925 ◽  
Author(s):  
M Tapani Hattula ◽  
Harriet C Wallin ◽  
◽  
R Andersen ◽  
K Blomberg ◽  
...  
Keyword(s):  
Glutamic Acid ◽  
Collaborative Study ◽  
Meat Products ◽  
Visible Range ◽  
Enzymatic Method ◽  
Study Materials ◽  
Enzymatic Determination ◽  
Relative Standard ◽  
The Mean

Abstract An enzymatic method for the determination of free glutamic acid in meat products and dried soups was collaboratively studied in 11 laboratories. In the presence of the enzyme glutamate dehydrogenase, L-giutamic acid is oxidatively deaminated by nicotinamide adenine dinucleotide (NAD) to 2-oxoglutarate. In a reaction catalyzed by diaphorase, the NADH thus formed converts 2-(p-iodophenyl)-3-(p-nitrophenyl)-5-phenyltetrazolium chloride to a formazan, which is measured in the visible range at 492 nm. Fourteen samples (7 samples of minced sausage and 7 samples of dried cauliflower soup) with glutamate contents varying between 0.4 and 16 g/kg were included In the study. Materials were distributed to participants as blind duplicates and as split level pairs. The mean relative standard deviation (RSDR) for reproducibility for the dried soup material containing glutamate between 7 and 16 g/kg was 4.6%. RSDR values for samples of minced sausage containing glutamate at lower levels (0.4-1.3 g/kg) were between 12 and 16%.

Combustion Method for Determination of Crude Protein in Meat and Meat Products: Collaborative Study

1993 ◽  
Vol 76 (4) ◽  
pp. 787-793 ◽  
Author(s):  
Brink Marcia King ◽  
Sebranek Joseph G. ◽  
◽  
C Anthony ◽  
P Coleman ◽  
...  
Keyword(s):  
Crude Protein ◽  
Collaborative Study ◽  
Meat Product ◽  
Meat Products ◽  
Combustion Method ◽  
Relative Standard ◽  
Kjeldahl Method ◽  
Standard Deviations ◽  
Meat Samples

Abstract Twelve laboratories participated in a collaborative study to compare a combustion method with the AOAC mercury catalyst Kjeldahl method (928.08) for the determination of crude protein in meat and meat products. Three different combustion instruments were used; consequently, the combustion method for this study is written in generic terms describing the principle, the apparatus specifications, and the performance requirements needed. Fifteen sample pairs were used for the study; each pair consisted of the same commercial meat product from each of 2 different manufacturers. Protein content of all samples ranged from about 10 to 20%. In addition, nicotinic acid and lysine monohydrochloride were used as standards to assess combustion equipment performance. All laboratories and all instruments performed the combustion method satisfactorily on the basis of results for the standards. For the meat samples, repeatability standard deviations (sr) ranged from 0.11 to 0.40 for the Kjeldahl method and from 0.12 to 0.41 for the combustion method; the repeatability relative standard deviations (RSDr) ranged from 0.82 to 2.41% and from 0.60 to 2.23% for the Kjeldahl and combustion methods, respectively. Reproducibility standard deviations (SR) ranged from 0.20 to 0.49 for the Kjeldahl method and from 0.18 to 0.46 for the combustion method, whereas the reproducibility relative standard deviations (RSDR) ranged from 1.59 to 2.84% for the Kjeldahl method and from 1.32 to 3.35% for the combustion method. Overall grand means were 15.59% protein for the Kjeldahl method and 15.75% protein for the combustion method. The combustion method was adopted first action by AOAC International.

scholarly journals Determination of Fat,Moisture, and Protein in Meat and Meat Products by Using the FOSS FoodScan Near-Infrared Spectrophotometer with FOSS Artificial Neural Network Calibration Model and Associated Database: Collaborative Study

2007 ◽  
Vol 90 (4) ◽  
pp. 1073-1083 ◽  
Author(s):  
Shirley Anderson ◽  
S Aldana ◽  
M Beggs ◽  
J Birkey ◽  
A Conquest ◽  
...  
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Standard Deviation ◽  
Near Infrared ◽  
Collaborative Study ◽  
Meat Products ◽  
Calibration Model ◽  
Relative Standard ◽  
Infrared Spectrophotometer

Abstract A collaborative study was conducted to evaluate the repeatability and reproducibility of the FOSS FoodScan near-infrared spectrophotometer with artificial neural network calibration model and database for the determination of fat, moisture, and protein in meat and meat products. Representative samples were homogenized by grinding according to AOAC Official Method 983.18. Approximately 180 g ground sample was placed in a 140 mm round sample dish, and the dish was placed in the FoodScan. The operator ID was entered, the meat product profile within the software was selected, and the scanning process was initiated by pressing the start button. Results were displayed for percent (g/100 g) fat, moisture, and protein. Ten blind duplicate samples were sent to 15 collaborators in the United States. The within-laboratory (repeatability) relative standard deviation (RSDr) ranged from 0.22 to 2.67% for fat, 0.23 to 0.92% for moisture, and 0.35 to 2.13% for protein. The between-laboratories (reproducibility) relative standard deviation (RSDR) ranged from 0.52 to 6.89% for fat, 0.39 to 1.55% for moisture, and 0.54 to 5.23% for protein. The method is recommended for Official First Action.

scholarly journals Enzymatic Determination of Lactose and Galactose in Foods: NMKL Collaborative Methods Performance Study

1997 ◽  
Vol 80 (3) ◽  
pp. 584-590 ◽  
Author(s):  
Antti Mustranta ◽  
Carola Östman ◽  
I Aminoff ◽  
P Baardseth ◽  
E Eklund ◽  
...  
Keyword(s):  
Milk Powder ◽  
Meat Products ◽  
Enzymatic Oxidation ◽  
Performance Study ◽  
Cereal Products ◽  
Enzymatic Determination ◽  
Relative Standard ◽  
Analytical Tools ◽  
Hydrolysis Of

Abstract Enzymes are widely used in food chemistry as analytical tools. An enzymatic method for determining lactose and galactose in foods was evaluated in an interlaboratory methods performance study by 12 laboratories in 4 countries. The method is based on enzymatic hydrolysis of lactose and enzymatic oxidation of the hydrolysis products. The exchange of the coenzyme in the second reaction is the basis of quantitation. The method may be used for various types of foods, such as liquid and solid milk products, meat products, cereal products, fats, dressings, sweets, chocolate, and foods for special dietary uses. It is also applicable to lactose-free foods but not to products in which lactose has been partially hydrolyzed enzymatically to glucose and galactose. Six commonly used foodstuffs with lactose concentrations ranging from 0.4 g/100 g to 40 g/100 g and galactose concentrations up to 0.7 g/100 g were analyzed: crisp rye bread, milk chocolate, sausage, cheese, margarine, and baby food containing milk powder. They were distributed to the 12 participants as 12 randomly numbered test samples, representing blind duplicates of the 6 materials. The relative standard deviations for reproducibility (RSDR) were between 2.3-11% for lactose and 6.8-50% for galactose.

Comparison of the Volhard and Potentiometric Methods for the Determination of Chloride in Meat Products: Collaborative Study

1985 ◽  
Vol 68 (3) ◽  
pp. 480-484
Author(s):  
Paul R Beljaars ◽  
William Horwitz
Keyword(s):  
Sodium Chloride ◽  
Collaborative Study ◽  
Meat Products ◽  
Potentiometric Method ◽  
Collaborative Studies ◽  
Relative Standard ◽  
Luncheon Meat ◽  
Iso 5725 ◽  
Good Agreement

Abstract A collaborative study of the determination of chloride in meat products was conducted by the International Organization for Standardization (ISO) to compare the ISO 1841 method (Volhard titration) with the FAO/WHO Codex Alimentarius Committee method (potentiometric titration). Five canned luncheon meat products containing 0.25-2.0% sodium chloride at 4 different spiking levels were analyzed by 11 laboratories. The data were analyzed by ISO statistics (ISO 5725) and by AOAC statistics (Youden-Steiner), the major differences being in the rejection of outliers and in the statement of precision parameters. Good agreement was found between the mean chloride contents of the products as determined by both methods and with the added amounts, although statistically significantly higher sodium chloride recoveries were obtained with the potentiometric method. The within-laboratory variability (repeatability) is greater for the Volhard method, especially for chloride levels below 1.0%. Therefore it is proposed to set the lowest level of determination for the Volhard method at about 1.0% sodium chloride. The among-laboratories variability (reproducibility) of the potentiometric method was comparable with the results from the collaborative studies for chloride in cheese, giving acceptable values for relative standard deviations of 1.5-3.0% for meat products with 0.3-2.0% added sodium chloride. It is recommended that further work be conducted to reduce or eliminate the systematic error present with the potentiometric method as applied to meat and meat

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.

scholarly journals Indirect and Direct Determination of the Casein Content of Milk by Kjeldahl Nitrogen Analysis: Collaborative Study

1998 ◽  
Vol 81 (4) ◽  
pp. 763-774 ◽  
Author(s):  
Joanna M Lynch ◽  
David M Barbano ◽  
J Richard Fleming
Keyword(s):  
Standard Deviation ◽  
Nitrogen Content ◽  
Relative Standard Deviation ◽  
Collaborative Study ◽  
Direct Determination ◽  
Raw Milk ◽  
Method Performance ◽  
Relative Standard ◽  
Milk Casein

Abstract The classic method for determination of milk casein is based on precipitation of casein at pH 4.6. Precipitated milk casein is removed by filtration and the nitrogen content of either the precipitate (direct casein method) or filtrate (noncasein nitrogen; NCN) is determined by Kjeldahl analysis. For the indirect casein method, milk total nitrogen (TN; Method 991.20) is also determined and casein is calculated as TN minus NCN. Ten laboratories tested 9 pairs of blind duplicate raw milk materials with a casein range of 2.42- 3.05℅ by both the direct and indirect casein methods. Statistical performance expressed in protein equivalents (nitrogen ⨯ 6.38) with invalid and outlier data removed was as follows: NCN method (wt%), mean = 0.762, sr = 0.010, SR = 0.016, repeatability relative standard deviation (RSDr) = 1.287℅, reproducibility relative standard deviation (RSDR) = 2.146%; indirect casein method (wt℅), mean = 2.585, repeatability = 0.015, reproducibility = 0.022, RSDr = 0.560℅, RSDR = 0.841; direct casein method (wt℅), mean = 2.575, sr = 0.015, sR = 0.025, RSDr = 0.597℅, RSDR = 0.988℅. Method performance was acceptable and comparable to similar Kjeldahl methods for determining nitrogen content of milk (Methods 991.20, 991.21,991.22, 991.23). The direct casein, indirect casein, and noncasein nitrogen methods have been adopted by AOAC INTERNATIONAL.

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