bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of Aegys MI 600 Fourier Transform Infrared Milk Analyzer for Analysis of Fat, Protein, Lactose, and Solids Nonfat: A Compilation of Eight Independent Studies
Authors: Lanher Bertrand S
Published: February 2020

The Aegys Mi 600 Fourier transform-infrared milk analyzer was evaluated for performance in 8 independent laboratories in Europe, the United States, and Australia. This instrument, equipped with a mid-infrared source, a temperature-controlled transmission flow cell or cuvette, and detection device, uses interferometry for wavelength generation; multilinear regression was used to create calibration equations for measurement of fat, protein, lactose, and solids nonfat. Each instrument was tested independently for various performance criteria including but not limited to accuracy in calibration and validation, repeatability, and purge efficiency. Mean difference for accuracy and standard deviation of differences for accuracy observed in each laboratory were well within AOAC requirements (<0.05 and <0.06%, respectively) as were the mean of diffferences for repeatability and the standard deviation of differences for repeatability (<0.02 and <0.02%, respectively). Observed purge efficiency was better than 99.0%. In addition, zero stability, instrument reproducibility over 5 days without recalibration, and homogenization efficiency were successfully tested. On the basis of the results, each instrument tested was approved for use for milk payment and/or dairy herd improvement in the country in which it was tested. The results demonstrate that the Aegys Mi 600 meets the requirements of the AOAC Official Method 972.16. The midinfrared spectroscopic method for determination of fat, lactose, protein, and solids in milk has been modified and adopted revised first action by AOAC INTERNATIONAL.
Enzyme Immunoassay for Determination of Peanut Proteins in Food Products
Authors: Yeung Jupiter M , Collins Peter G
Published: February 2020

Food allergy presents a problem for many parts of society, including sensitive subjects, schools, health authorities, and the food industry. Once food allergy is diagnosed, dietary avoidance is the principle method of management. Because trace levels of peanuts can elicit an adverse to fatal reaction, unintentional exposure to the offending allergens may have devastating consequences to sensitive individuals. However, determination of trace amounts of unintentional peanut contamination in our food supply is very difficult. Recently, we developed polyclonal antibodies specific to peanut proteins that do not cross-react with 22 legumes, tree nuts, or other common snack ingredients. An antiserum containing the polyclonal antibodies was used to develop a sensitive enzyme-linked immunosorbent assay (ELISA) for determination of peanut proteins in snack foods. This study reports the first successful ELISA test to detect trace amounts of peanut allergens in a variety of foods. The concentration of peanut protein that inhibited 50% of antibody–antigen binding (IC50) was 12 ng/mL, the linear range was 1–63 ng/mL, and the detection limit was 400 ng/g (ppb) for the various foods tested. Recoveries ranged from 68 to 90%, with coefficients of variation of 2–22%, depending on the commodity. Using this new procedure, allergy-related complaint samples from various food groups were analyzed, and undeclared peanut proteins were identified in some products.
Effect of Sample Introduction and Atmospheric Blank on Determination of Nitrogen (Crude Protein) by Combustion
Authors: Sachen Robert W , Thiex Nancy J
Published: February 2020

To reduce analysis time, reagent use, and chemical waste, existing Kjeldahl methods for crude protein were converted to combustion methods. When validating the combustion method for various samples, a high bias for the combustion method compared with the Kjeldahl method was apparent for high-fiber samples. The bias was sample dependent, varying from 0.15 to 1.38% crude protein for hay and corn silage samples. The bias was repeatable among 3 laboratories using identical instruments. Studies showed the bias was related to uncorrected atmospheric blanks. Various means to correct for the blank were studied, including pelleting of sample under high pressures to remove atmospheric nitrogen. Pelleting samples at a pressure of >1000 lbs provides combustion crude protein values consistent with Kjeldahl values.
Optimization of a Liquid Chromatographic Method for Determination of Amines in Fish
Authors: Michel Vallé , Malle Pierre , Bouquelet Stephane
Published: February 2020

A liquid chromatographic method is described for the determination of 9 amines in fish: ammonia, methylamine, tryptamine, putrescine, cadaverine, histamine, tyramine, spermidine, and spermine. The amines are extracted with 0.2M perchloric acid and labeled with dansyl chloride. After labeling, proline is added to neutralize excess dansyl chloride. The amines are separated on a Kromasil C18 column using a water-acetonitrile elution gradient. Handling time is restricted to 40 min, and an injection is possible every 30 min, thus allowing automation and routine analysis.
Determination of Ethephon in Pesticide Formulations by Headspace Gas Chromatography
Authors: Køppen Benny
Published: February 2020

A method is described for the determination of ethephon in pesticide formulations. The method uses headspace gas chromatography to determine ethylene formed from the decomposition of ethephon by the addition of base. Method performance with respect to linearity and precision was evaluated. Results from analyses of various pesticide formulations were compared with results obtained by using the official titrimetric method. The usefulness of the method was demonstrated for formulation control.
Comparison of Closed-Vessel and Focused Open-Vessel Microwave Dissolution for Determination of Cadmium, Copper, Lead, and Selenium in Wheat, Wheat Products, Corn Bran, and Rice Flour by Transverse-Heated Graphite Furnace Atomic Absorption Spectrometry
Authors: Gawalko Eugene J , Nowicki Thomas W , Babb Jeff , Tkachuk Russell , Wu Shaole
Published: February 2020

A method is described for the determination of Pb, Cd, Cu, and Se in cereal samples. An atomic absorption spectrometer equipped with a transverseheated graphite furnace with Zeeman background correction was used for all determinations. Sample preparation was performed by closed-vessel microwave digestion using nitric acid and focused openvessel microwave digestion using nitric acid-hydrogen peroxide. Both techniques were evaluated by using 15 cereal reference materials and comparing results with certified or reference values for each element. Cereal reference standards obtained from the Community Bureau of Reference (Europe), the National Institute of Standards and Technology (USA), the National Institute for Environmental Studies (Japan), the National Research Centre for Certified Reference Materials (People's Republic of China), and the Canadian Grain Commission were used. Application of a series of t-tests, conducted according to Sidak's modified Bonerroni t-procedure, showed that both techniques yielded accurate results for cereal reference materials. Some differences from certified and reference values, however, were found for each element.
Use of Desirability Functions Associated with a Chemometric Method To Optimize Separation of a Compound Mixture by Liquid Chromatography
Authors: Guillaume Yves , Peyrin Eric , Guinchard Christiane
Published: February 2020

A chemometric method using a desirability function was used to optimize the liquid chromatographic separation of 10 benzodiazepines in a minimum analysis time. Most efficient separation was achieved with acetonitrile–water (60 + 40) at a flow rate of 1 mL/min and a column temperature of 47°C.
Determination of Moisture in Raisins
Authors: Katsaboxakis Kostanttne
Published: February 2020

The determination of moisture in Soultanina raisins by drying in a steam bath with diatomaceous earth to constant weight (about 70 min) was compared with the official AOAC Method 22.013, which uses asbestos and requires 6 h of drying at 70°C under <100 mm Hg. Five different samples (moisture 11-22%) were analyzed by the 2 methods; the mean values of 9 replications did not differ significantly. The new method is rapid and simple, and it eliminates asbestos, a known carcinogenic substance, from the determination.
Extraction and Cleanup of Organochlorine and Organophosphorus Pesticide Residues in Fats by Supercritical Fluid Techniques
Authors: Hopper Marvin L
Published: February 2020

A supercritical fluid extraction and cleanup procedure was developed for separating organochlorine and organophosphorus pesticides from fats. Supercritical carbon dioxide modified with 3% (v/v) acetonitrile was used to extract the pesticides at 6O°C and separate the pesticides from the fats at 4000 psi and 95°C on an in-line C? silica-based column. The extraction and cleanup procedure gave good recoveries for 43 of 62 nonpolar to moderately polar organochlorine and organophosphorus pesticides from fats, whereas 49 were recovered through conventional Florisil column cleanup before quantitation. This procedure can extract and clean up pesticide residues from 0.65 g animalbased fat and 1.0 g oils. Coeluted residues in the pesticide fraction ranged from 2.5 mg for butterfat to 0.8 mg for corn oil. Results for samples analyzed with this integrated extraction cleanup procedure were reproducible and comparable with results obtained with the current Total Diet Study methodology.
The Horwitz Function Revisited
Authors: Thompson Michael , Lowthian Philip J
Published: February 2020

A statistical test was made of the Horwitz function, an empirical relationship between the reproducibility precision of an analytical method and the concentration of the analyte regardless of the nature of the analyte, matrix, and the method. The large data set (7502 observations) was compiled by Horwitz from collaborative trials (method performance studies) spanning the period 1915 to 1995. The data followed the Horwitz function well down to concentrations of about 10-8 (10 ppb), but they followed a more stringent specification at lower concentrations. This discrepancy may be due to special circumstances prevailing in collaborative trials at very low concentrations. Deviations of individual observations from the function were in large part accounted for by random variations. No consequential improvement in precision with time was found.
Improved Protocol for an Oxygen Electrode Method for Determining Hydrogen Peroxide in Foods
Authors: Miyamoto Fumio , Saeki Masanobu , Yoshizawa Takumi
Published: February 2020

An oxygen electrode method for determining residual hydrogen peroxide in foods has been further improved. Pretreatment, which includes extraction and neutralization, is done in a hydrogen peroxide extraction apparatus with nitrogen gas bubbling. The hydrogen peroxide concentration of the sample is corrected by subtracting the sample blank value, obtained for the sample through catalase treatment. Bubbling with nitrogen gas effectively minimized the sample blank value, making this method suitable for accurate determination of trace amounts of hydrogen peroxide in foods. Recoveries of hydrogen peroxide added at 1-10 μg/g were 77.8-107.1% by the present method. These recoveries are similar to or higher than those by the Japanese standard method and by another modified oxygen electrode method. Concentrations of naturally occurring hydrogen peroxide in solid foods were <0.87 μg/g by the present method, lower than those by either the standard method or another modified oxygen electrode method.
Preparation of Some Toxic Metabolites of Disulfoton, Phorate, and Terbufos, Their Separation by Thin-Layer Chromatography and Confirmation by Electron Impact Mass Spectrometry
Authors: Simonovska Breda
Published: February 2020

Milligram quantities of sulfoxides, sulfones, and oxygen analogue (oxon) sulfones of the insecticides disulfoton, phorate, and terbufos were prepared by selective oxidation. Pure insecticides or acetone extracts of granular formulations served as reactants. Structures of 9 compounds were confirmed by comparing their electron impact mass spectra (EI-MS), obtained by the direct inlet system with published data. Thin-layer chromatography (TLC) on silica gel was used to screen oxidation products and to purify products. Products were detected by spraying plates with PdCl2 reagent and exposing to iodine vapors. An esterase inhibition technique gave low detection limits, which are promising for residue analysis.
Colorimetric Determination of Selenium in Mineral Premixes
Authors: Hurlbut Jeffrey A , Burkepile Roger G , Geisler Carolyn A , Kliak Philip James , Rummel Nathan G
Published: February 2020

A method is described for determination of sodium selenite or sodium selenate in mineral-based premixes. It is based on the formation of intense-yellow piazselenol by Se(IV) and 3,3’-diaminobenzid- ine. Mineral premixes typically contain calcium carbonate as a base material and magnesium carbonate, silicon dioxide, and iron(lll) oxide as minor components or additives. In this method, the premix is digested briefly in nitric acid, diluted with water, and filtered to remove any iron(lll) oxide. Ethylenediaminetetraacetic acid and HCI are added to the filtrate, which is heated to near boiling for 1 h to convert any selenate to selenite. After heating, the solution is buffered between pH 2 and 3 with NaOH and formic acid and treated with NH2OH and EDTA; any Se present forms a complex with 3,3’- diaminobenzidine at 60°C. The solution is made basic with NH4OH, and the piazselenol is extracted into toluene. The absorbance of the complex in dried toluene is measured at 420 nm. The method was validated independently by 2 laboratories. Samples analyzed included calcium carbonate fortified with 100, 200, and 300 μg Se in the form of sodium selenite or sodium selenate, a calcium carbonate premix containing sodium selenite, a calcium carbonate premix containing sodium selenate, and a commercial premix; 5 replicates of each sample type were analyzed by each laboratory. Average recoveries ranged from 89 to 109% with coefficients of variation from 1.2 to 13.6%.
Determination of Sulfonamides in Edible Salmon Tissue by Liquid Chromatography with Postcolumn Derivatization and Fluorescence Detection
Authors: Gehring Theresa A , Rushing Larry G , Thompson Harold C
Published: February 2020

Fourteen sulfonamides—sulfanilamide, sulfadiazine, sulfathiazole, sulfapyridine, sulfam- erazine, sulfamethazine, sulfamethizole, sulfamethoxypyridazine, sulfachloropyridazine, sulfamonomethoxine, suļfadoxine, sulfamethoxazole, sulfadimethoxine, and sulfaquinoxoline—residues of which could be found in aquacultured species, were separated in <25 min by reversed-phase (C18) liquid chromatography (LC) with gradient elution. Analytes were extracted from edible salmon tissue (muscle and adhering skin) with acetonitrile—2% aqueous acetic acid, isolated with 2 liquid-liquid partitionings, and derivatized with fluorescamine after eluting from the column. The derivatives were detected by fluorescence. Recoveries (n = 4) from coho salmon fortified with sulfonamides at 5,10, and 20 ng/g tissue averaged 79.7± 7.3, 84.6 ± 7.7, and 88.2 ± 7.1%, respectively. Limits of quantitation were 5 ng/g tissue, for sulfanilamide, sulfamethoxypyridazine, and sulfaquinoxoline and 1 ng/g tissue for the remaining sulfonamides.
Assurance Polyclonal Enzyme Immunoassay for Detection of Listeria monocytogenes and Related Listeria Species in Selected Foods: Collaborative Study
Authors: Feldsine Philip T , Lienau Andrew H , Forgey Robin L , Calhoon Roger D ,   Collaborators:, Al-Hasani S , Arling V , Bandiera T , Barnes M , Beatty S , Beaudoin A , Beyer D , Bryant J , Burzynski M , Carey B , Copeland F , Culver D , Destro C , Diaz B , Franke W , Gallagher D , Gary J , Harper M , Hermann C , Isakson T , Jenkins P , Johnson S , Ke J , Krause C , Lange K , Trottier Y-L , Maki G , McDonagh S , McLenaghan J , Miller L , Phebus R , Raghubeer E , Redding R , Retzlaff D , Richter D , Ritger C , Robinson J , Saunders L , Schwants D , Tuncan E , Vanderbilt K , Ward D , West D , Woo L , Zebchek A
Published: February 2020

Six foods representing a variety of food products were analyzed by the Assurance Listeria polyclonal enzyme immunoassay (EIA) and by either the Bacteriological Analytical Manual or the U.S. Department of Agriculture culture method for detecting Listeria monocytogenes and related Listeria species. Samples of each food type, at each inoculation level, were analyzed simultaneously by both methods. A total of 19 laboratories representing federal government agencies and private industry in the United States and Canada participated. Food types were inoculated with Listeria species including L. monocytogenes, with the exception of 3 lots of green beans, which were naturally contaminated. During this study, 1764 samples and controls were analyzed and confirmed, of which 492 were positive and 947 were negative by both methods. There were 159 samples that were positive by culture method but negative by the EIA and 188 that were negative by culture method but positive by EIA. Twenty-two samples were negative by EIA and by culture method but confirmed positive when Assurance selective enrichment broths were subcultured to selective agar. The Assurance polyclonal EIA for detecting L. monocytogenes and related Listeria species in foods has been adopted first action by AOAC INTERNATIONAL.
Fumonisin Levels in Uruguayan Corn Products
Authors: Piñeiro Maya S , Silva Gabriela E , Scott Peter M , Lawrence Guillaume A , Stack Michael E
Published: February 2020

A survey was conducted to evaluate fumonisins FB1 and FB2 in Uruguayan corn products. Sixty- four samples of different local brands were purchased from retail stores during a 15-month period and analyzed for FB1 and FB2 by methanol-water extraction, cleanup with a 1 mL strong-anion-exchange solid-phase extraction column, and liquid chromatography with o-pthaldialdehyde-2-mercaptoethanol derivatization and fluorescence detection. Contamination levels for FB1 varied from 50 ng/g (detection limit) to 6342 ng/g. Values were highest in feed samples (up to 6342 ng/g), unprocessed corn kernel (up to 3688 ng/g), and milled products, which included polenta (up to 427 ng/g). They were lowest in processed corn kernel (up to 155 ng/g) and snacks (up to 314 ng/g). FB2 was determined in one-fourth of the total samples and detected at trace levels in only one feed sample. The data demonstrated the natural occurrence of fumonisins in corn products in Uruguay. Feed and polenta that contain fumonisins could be of concern because they are consumed in large amounts and are often the main nutrient source in Uruguay.
Modification of Babcock Method to Eliminate Fat Testing Bias Between Babcock and Ether Extraction Methods (Modification of AOAC Official Methods 989.04 and 995.18): Collaborative Study
Authors: Lynch Joanna M , Barbano David M , Fleming J Richard
Published: February 2020

The Babcock test for determining fat in milk (AOAC Official Method 989.04) and in cream (AOAC Official Method 995.18) gives consistently higher test results than does the modified Mojonnier ether extraction reference method (AOAC Official Methods 989.05 and 995.19). To decrease the density of material in Babcock columns and thus lower test results, the Babcock method was modified by lowering the temperatures used at various points in the method, from about 57.5° to 48°C. Using the AOAC collaborative study format, 9 laboratories tested 9 pairs of blind duplicate raw milk samples (fat range 2.5–5.7%) and 9 pairs of blind duplicate heat-treated cream samples (fat range 30–45%) using the temperature modified (TM) Babcock method. The ether extraction test was conducted as the reference method. The statistical performance (invalid and outlier data removed) of the TM Babcock method was, for milk: percent fat value of 4.110, repeatability standard deviation (sr) value of 0.037, reproducibility standard deviation (sR) value of 0.047, repeatability relative standard deviation (RSDr) value of 0.901% and reproducibility relative standard deviation (RSDR) value of 1.147%; and for cream: percent fat value of 37.555, sr value of 0.258, sR value of 0.353, RSDr value of 0.687% and RSDR value of 0.940%. The TM Babcock method performance was acceptable but not as good as that achieved in previous studies of the unmodified method. For the TM Babcock and ether methods, respectively, average percentages fat were 4.110 and 4.114 for milk, and 37.555 and 37.485 for cream. Temperature modification statistically eliminated the testing bias between methods. The tem-perature modifications of the Babcock methods for determination of fat in milk and cream (989.04 and 995.18) have been adopted revised first action by AOAC INTERNATIONAL.
Liquid Chromatographic Determination of Safrole in Sassafras-Derived Herbal Products
Authors: Carlson Marvin , Thompson Richard
Published: February 2020

A liquid chromatographic (LC) method was developed for determining safrole in herbal products derived from sassafras (Sassafras albidumf as well as related compounds such as isosafrole and dihydrosafrole. The procedure involves solvent extraction and isolation of analyte by reversed-phase LC with UV detection at 235 nm. Safrole is resolved from related compounds and other sample constituents including thymol, a component of thyme. A linear concentration range of 0.003-0.200 mg/mL was obtained for safrole, isosafrole, and dihydrosafrole. Limits of detection (LOD) and quantitation (LOQ) were 0.0015 and 0.0051 μg/mL for safrole, 0.0018 and 0.0061 μg/mL for isosafrole, and 0.0038 and 0.0125 μg/mL for dihydrosafrole, respectively. Intraday relative standard deviations (RSDs) for safrole (n= 5) from various samples ranged from 1.30 to 5.39% at analyte levels of 0.01-1.5%. Safrole contents of 26 samples including root bark powder, leaves, oils, tea concentrate, herbal extract tinctures, and herbal powder capsules ranged from <LOD for most leaf samples to 92.4% for an oil. Recoveries of safrole from fortified samples ranged from 83.6% for an oil to 117.2% for a tincture preparation. Safrole contents of 0.09-4.66 mg/cup were found for brewed teas prepared from sassafras root bark powders and tinctures.
Determination of β-Carotene in Commercial Foods: Interlaboratory Study
Authors: Schuep Willy , Schierle Joseph
Published: February 2020

Two sample preparation procedures for determination of total β-carotene and (all-)-β-carotene were tested in a collaborative study involving 14 laboratories and using 4 commercial products containing supplemented or natural β-carotene. One assay used classical sample preparation, consisting of saponification, extraction, washing, and drying ofthe extract and redissolution of residue for liquid chromatography (LC). The other assay used simple extraction without saponification. LC conditions were left for the analysts to decide as long as aclear separation of lycopene and ϑ-carotene from Bcarotene was achieved. Mean contents of test samples ranged from 0.3 to 18 mg/100 g for total β-carotene and from 0.2 to 16 mg/100 g for (all-)-β-carotene. Repeatability relative standard deviations (RSDr)for total B-carotene ranged from 2.9 to 5.6% and relative reproducibility standard deviation (RSDR) ranged from 6.5 to 15%. Corresponding values for(all-)-β-carotene were 3.3-5.1 % for RSDr and 8.4- 14% for RSDR. Excluding the (Z)-isomers from uantitation of β-carotene can result in significant underestimation of the effective β-carotene content especially if the LC systems used is high quality.
Application of Immunoaffinity Columns to Mycotoxin Analysis
Authors: Scott Peter M , Trucksess Mary W
Published: February 2020

Immunoaffinity columns (lACs) are widely used for cleanup and isolation of mycotoxins extracted from foods and biological fluids, particularly afla-toxins, ochratoxin A, and fumonisinsẳ The columns are prepared by binding antibodies specific for a given mycotoxin to a specially activated solid-phase support and packing the support suspended in aqueous buffer solution into a cartridge. The mycotoxin in the extract or fluid binds to the antibody, impurities are removed with water or aqueous solution, and then the mycotoxin is desorbed with a miscible solvent such as methanol. Further separation can be performed with lAC, followed by liquid chromatographic (LC) quantitation, either off-line or on-line in an automated system, or by fluorometryằ lACs have been used by laboratories that developed the antibodies but are also available commercially for aflatoxins, ochratoxin A, fumonis-ins, zearalenone, and deoxynivalenolễ Among commercial lACs, Aflatest P is used as the cleanup step in an LC method and in a solution fluorometry method for corn, peanuts, and peanut butter that was adopted as an AOAC INTERNATIONAL Official Method after evaluation by an international collaborative study. As part of a fluorometer-based test kit, aflatest P was further certified by the AOAC Research Institute to measure total aflatoxins in 10 grains and grain products. lACs can concentrate the analyte from a large amount of sample, allowing detection limits at low parts-per-trillion levels in some cases (e.g., for aflatoxin Mi and ochratoxin A in liquid food matrixes). Regeneration of lACs for reuse in aflatoxin, ochratoxin A, fumon-isin, and zearalenone analyses has been investigated.
Determination of Chromium in Feeds by Automated Microwave Digestion and Atomic Absorption Spectrophotometry
Authors: Gallo Pasquale , Serpe Luigi , Brambilla Gianfranco
Published: February 2020

Chromium, as trivalent organic form, has been recently proposed as feed additive to improve animal welfare and the quality-quantity of meat productions. To control its use in animal production we developed an analytical method that consisted of sample digestion by a commercially available focused microwave system and, subsequently, metal determination by graphite furnace atomic absorption spectrophotometry. The mineralization step was performed by treating the samples with a nitric acid-sulphuric acid-hydrogen peroxide mixture. Complete sample digestion was achieved in 26 min, as compared to 8-12 h or more required by dry ashing. To determine method accuracy and precision, we analyzed both feeds spiked at different Cr concentrations and a reference plant material. We found that mean metal recoveries ranged from 98.7 to 102.7% and for the reference material we obtained an excellent agreement between calculated and certified value. Quantitative Cr yields and relative coefficients of variation between 0.77 and 9.7% were very good and accounted for method accuracy and reliability. Finally, we applied the developed method to Cr analysis of some commercial feeds and the results were compared with those obtained by dry-ashing procedure.
Discrimination of Sound and Granary-Weevil-Larva-Infested Wheat Kernels by Near-Infrared Diffuse Reflectance Spectroscopy
Authors: Ghaedian Ahmad R , Wehling Randy L
Published: February 2020

Sound and infested wheat kernels containing lateinstar granary weevil larvae, as identified by X-ray analysis, were used to evaluate the ability of nearinfrared (NIR) spectroscopy to predict the presence of insect larvae in individual wheat kernels. Diffuse reflectance spectra at 1100-2500 nm were recorded from individual infested and sound kernels. Principal component analysis (PCA) of NIR spectra from sound kernels was used to construct calibration models by calculation of Mahalanobis distances. Calibration models were then applied to spectra obtainedfrom both sound and infested kernels in a separate validation set. A 5-factor PCA model using data from a first-derivative spectral transformation was the best model for correctly classifying kernels in an expanded validation sample set, including 100% of sound, 93% of infested, 95% of sound air dried, 86% of infested air dried kernels, and 90% of sound kernels from 6 wheat varieties. Calibrations using the spectral region from 1100 to 1900 nm were least sensitive to kernel moisture differences. Similar results were obtained when discriminant analysis was applied to log 1/R data from selected discrete wavelengths of NIR spectra.
Rapid Microbiological Methods with Hazard Analysis Critical Control Point
Authors: Griffiths Mansel W
Published: February 2020

The proactive approach to ensuring food safety termed hazard analysis critical control point (HACCP) was introduced in the 1960s by the Pillsbury Company, in collaboration with the U.S. Army Natick Laboratories and National Aeronautics and Space Administration, to help guarantee that astronauts would not be incapacitated by the trauma of foodborne illness during space flights. The approach has subsequently been adopted as the standard food safety management system worldwide and is seen as forming the basis for harmonization of food inspection regulations necessitated by trade agreements such as General Agreement on Tariffs and Trade and North American Free Trade Agreement as the move toward globalization of trade in food products gains momentum. The new U.S. Department of Agriculture Mega-Reg requires mandatory introduction of HACCP, and the Food Safety Enhancement Program of Agriculture and Agri-food Canada, as well as the “due diligence” legislation of the European Union, is centered on HACCP principles.
Comparison of Antibody-Direct Epifluorescent Filter Technique with the Most Probable Number Procedure for Rapid Enumeration of Listeria in Fresh Vegetables
Authors: Tortorello Mary L , Reineke Karl F , Stewart Diana S
Published: February 2020

The antibody-direct epifluorescent filter (Ab-DEFT) technique was evaluated as a rapid alternative to the most probable number (MPN) method for enumeration of artificially inoculated Listeria monocytogenes in ready-to-eat packaged salads and other fresh vegetables. Ab-DEFT was performed by homogenization of food in mesh-lined Stomacher bags, followed by prefiltration of homogenate through a 5 μm pore nylon filter, and passage of filtrate through a 0.4 μm pore black polycarbonate filter to collect and concentrate Listeria cells. After cells were stained with a fluorochrome-labeled polyclonal antibody to Listeria, the filter surface was examined by epifluorescence microscopy, and fluorescent cells were counted. A 3-tube MPN procedure was performed by successive enrichments of homogenized foods in Listeria enrichment and Fraser broths, followed by selective plating. Ab-DEFT provided quantitative determinations of Listeria cells that correlated with plate counts and MPN estimates in a linear response over a range of cell concentrations from 10 to 107 colony forming units (CFU)/mL. Microbial backgrounds as high as 108 CFU/mL did not affect performance of Ab-DEFT. In contrast to the MPN method, which required 5 days to perform, quantitation by Ab-DEFT could be completed in less than 1 h. Despite cross-reactivities demonstrated by the polyclonal fluorescent antibody, the potential of Ab-DEFT as a rapid alternative to MPN for microbial cell enumeration was evident.
Determination of Aflatoxins in Beer
Authors: Scott Peter M , Lawrence Guillaume A
Published: February 2020

Aflatoxins B1, B2, G1, and G2 were determined at parts-per-trillion levels in beer by immunoaffinity column cleanup and reversed-phase liquid chromatography (LC) with fluorescence detection after trifluoroacetic acid derivatization. Silanized vials were necessary for the evaporation step in order to obtain good recoveries of aflatoxins from spiked beer samples. Recoveries averaged 90–104%, 94%, 84–87%, and 89% for aflatoxins B1, B2, G1, and G2, respectively, at levels of 9.7–133 ng B1, 46 ng B2, 35–140 ng G1 and 41 ng G2/L. Detection limits were 19–20 ng/L for aflatoxins B1 and G1 and 15–16 ng/L for aflatoxins B2 and G2 (signal-to-noise ratio = 3:1) obtained by using an excitation wavelength of 360 nm; at 340 nm these detection limits were lowered to about 2 ng/L. Analysis of 24 beer samples, the majority from the United States and Mexico, showed natural contamination of one sample of Mexican beer at 49 ng B1/L when determined at 360 nm excitation, but reanalysis of 23 of the samples using 340 nm excitation indicated that an additional 4 Mexican samples and one Brazilian sample contained anatoxin B1 at low levels (< 10 ng/L).
Determination of Lead in Wine by Graphite Furnace Atomic Absorption Spectrophotometry: Interlaboratory Study
Authors: Brereton Paul A , Robb Paul , Sargent Christine M , Crews Helen M , Wood Roger ,   Collaborators:, Caputi A , Carrington J , Chetaneau B , Cohen S , Davies R W , Davis W S , Dix E , Ennion; R A , Furniss S , Gardner J W , Griffin J , Hampton I , Harrison N , Heide C , Hollywood F , Hopkins J , Liddle P , Meagher J , Osborne P Y , Piatt T , Postlethwaite K , Procter J , Reynolds E B , Robinson J , Smith M , Sparkes S , Stangroom S G , Stevens R , Sutton P , Swain S , Turnbull J , Vidal J P , Waller J M , Zaiger K
Published: February 2020

An interlaboratory study of a graphite furnace atomic absorption spectrophotometry (GFAAS) method for the determination of lead in wine was conducted. Seventeen laboratories from France, United States, and the United Kingdom, using a variety of GFAAS instruments, took part in the study. The method incorporated a novel matrix-matching procedure to minimize matrix effects between standards and samples. Six wine test materials were prepared and sent to participants as 12 blind duplicate or split level samples. There was good agreement between results obtained from participants and target values (24–279 μg/L) obtained with an inductively coupled plasma-mass spectrometry method. The precision of the GFAAS method was well within the range predicted by the Horwitz equation for the 6 test materials analyzed. Repeatability standard deviations ranged from 3 to 17%. Reproducibility standard deviations were in the range of 10 to 30%. The method is recommended for use for official purposes.
Determination of Carbamate Insecticides in Apples, Pears, and Lettuce by LC with UV Detector
Authors: Minelli Elizabeth V , Angioni Alberto , Melis Marinella , Pirisi Filippo M , Cabras Paolo
Published: February 2020

A simple and rapid method was developed for determination of 8 carbamate insecticides and 10 of their metabolites in apples, pears, and lettuce by liquid chromatography with UV diode array detector. With this method no derivatization is needed. Carbamates not belonging to the N-methylcarbamate class and metabolites without the N-methyl group can also be determined.
Statistical Classification of Seafood Quality
Authors: Ellis P Christopher , Silva Mary Lou , Lee Chong M
Published: February 2020

Discriminant function analysis (DFA) was used to classify the freshness quality of lean fish, fatty fish, and shrimp as either acceptable (Class 1), marginal (Class 2), or unacceptable (Class 3). Fresh and frozen survey samples were statistically classified following an initial precategorization using sensory, chemical, and microbiological indices as predictor variables. Computer elimination of nonsignificant predictor tests, p > 0.05, was used to optimize the test protocol. DFA correctly classified 98.5% of 67 preclassed lean fish samples (34 Class 1; 13 Class 2; 20 Class 3), 86.2% of 58 preclassed fatty fish samples (22 Class 1; 16 Class 2; 20 Class 3), and 98.7% of 79 preclassed shrimp samples (45 Class 1; 18 Class 2; 16 Class 3) by using all the quality indices. Computer selection of significant predictor indices at p < 0.05 yielded correct predicted classifications of 95.5, 81.0, and 97.5%, respectively. The number of tests required to effectively categorize quality were reduced from 15 to 3 for lean fish, from 13 to 3 for fatty fish, and from 11 to 6 for shrimp, with minimal losses in prediction accuracy and a substantial reduction in analysis time.
A Precollaborative Study of Weight Determination Methods for Quick Frozen Shrimp
Authors: Fox Dobson Jane E , Mcclure Foster D , Rainosek Alvin P
Published: February 2020

A precollaborative study compared the accuracy and precision of official AOAC methods with other selected methods for determining net weight of IQF-glazed shrimp and block-glazed shrimp, assessed the ruggedness of the methods with respect to changes in the levels of the factors under study, and selected candidate methods for use in a collaborative study. Methods tested for determining deglazed (frozen) net weight of IQF-glazed shrimp were (1) AOAC Method 963.18 and (2) the Water Bath Dip Method. Methods tested for determining thawed net weight of IQF-glazed shrimp were (7) AOAC Method 967.13, (2) Modified AOAC Methodmnb 967.13, (3) Modified AOAC Methodpb 967.13, (4) the Codex Method, (5) the Air Thaw Method, and (6) Modified AOAC Method 963.18. The same methods except Modified AOAC Method 963.18 were tested for determining thawed net weight of block-glazed shrimp. A total of 864 0.45 kg (1 lb), 0.90 kg (2 lb), and 1.35 kg (3 lb) IQF-glazed shrimp test samples and 234 2.25 kg (5 lb) block-glazed shrimp test samples were collected. During sample preparation, test samples were subjected to either water with or without sodium tripolyphosphate (STP). During deglazing (IQF-glazed shrimp only) and/or thawing, test samples were allocated in a factorial design to assess the effects of STP presence (no STP and STP), sieve mesh sizes (2.83 and 2.38 mm; 0.11 and 0.09 in.), and sieve diameters (20 and 30 cm; 8 and 12 in.). During weighing, test samples werefurther allocated to a sequence of weighing procedures designed to assess the effects of using sieve weights (dry and wet) in combination with paper towel use (no and yes) and tared pan weights when calculating determined net weights. On the basis of the results of this precollaborative study, Modified AOAC Methodpb 967.13 and the Air Thaw Method seem to be the best methods to determine net weight of IQF-glazed and block-glazed shrimp. Therefore, to validate method choices in the collaborative study, the authors recommend analysis of IQF-glazed shrimp and block-glazed shrimp test samples, each prepared with or without STP, by Modified AOAC Methodpb 967.13 and the Air Thaw Method. To fulfill AOAC requirements, IQF-glazed shrimp and block-glazed shrimp test samples, each prepared with or without STP, must be analyzed by official methods: AOAC Method 963.18 (IQF-glazed shrimp only) and AOAC Method 967.13. During testing, sieve mesh size will be either 2.83 or 2.38 mm (0.11 or 0.09 in.), sieve diameter will be limited to 30 cm (12 in.), and weighing procedure will be limited to tared pan.
Cleanup Procedure for Monitoring Chlorinated Compounds in Animal Feed and Crops
Authors: Syhre Mona , Hanschmann Gudrun , Heber Ralf
Published: February 2020

abstract

A powerful cleanup procedure for determination of chlorinated pesticides and poly chlorinated biphenyls (PCBs) in difficult agricultural matrixes like feeds or crops was developed to eliminate the interferences in chromatograms obtained by gas chromatography with electron capture detection. The adsorption material used was ENVI-Carb, a graphitized nonporous carbon material. This procedure proved to be more reliable than the established cleanup procedure, which uses gel permeation chromatography and silica gel cartridges. Because ENVI-Carb cleanup delivers clear, colorless eluates with no interferences, chlorinated pesticides and PCBs may be detected at levels as low as 0.0004 mg/kg for monitoring purposes. Accuracy was validated through a series of recovery experiments.
In Vitro Study of Nicotine Release from Smokeless Tobacco
Authors: Nasr Moheb M , Reepmeyer John C , Tang Yubing
Published: February 2020

abstract

Four brands (Copenhagen Snuff, Skoal Bandit Classic, Skoal Wintergreen Long Cut, and Skoal Wintergreen Fine Cut) of smokeless tobacco products were tested for their rate of nicotine release into artificial saliva via direct contact or through a dialysis bag. Nicotine was determined by reversed-phase liquid chromatography. When samples were in direct contact with artificial saliva, most of the nicotine was released from the tobacco in the first minute. Nicotine release from Skoal Bandit Classic, marketed as smokeless tobacco in a sachet, was slower with the sachet intact than without the sachet. When smokeless tobacco and artificial saliva were placed inside a dialysis bag, nicotine release was much slower and primarily depended upon the permeability of the dialysis membrane. Although total nicotine was lowest for Skoal Bandit Classic, little difference was seen in nicotine release rates among the brands tested. When smokeless tobacco was placed in dialysis bags with artificial saliva outside, a significant difference was seen in rates of nicotine migration through the membrane. In this model, nicotine release from Copenhagen Snuff was much faster than from Skoal Bandit Classic with or without the sachet. This difference may be related to the pH of the smokeless tobacco products.
Protein Content of Wheat by Near-Infrared Spectroscopy of Whole Grain: Collaborative Study
Authors: Delwiche Stephen R , Pierce Richard O , Chung Okkyung K , Seabourn Bradford W ,   collaborators:, Baker L , Boyd T , Brenner c , Cain L , Chung E , Cohoef E , Delwiche S , Drapcho C , Flemm J , Gell A , Gerjets L , Gipson N , Guillemette R , Hughes R , Hurburgh C , Jackson C , Jessop D , Johnson D , Johnson D , Krouse R , LaCour C P , Lego M , Lewis V , Mbuvi S , McCaig T , Perbix K , Psotka J , Seabourn B
Published: February 2020

abstract

A collaborative study was performed to assess accuracy, repeatability, and reproducibility of a nearinfrared (near-IR) method for determining crude protein content (PC) of whole-grain wheat. Four types of commercially available near-IR instruments, representing various combinations of wavelength region, mode of energy capture, method of energy dispersion, and treatment of spectral data, were used. Eight, 9,10, and 11 collaborators were involved, the exact number depending on instrument type. All collaborators received 22 samples of whole-grain hard red winter (HRW) wheat. They were furnished reference PCs (i.e., protein concentrations, w/w) corrected to a 12% moisture basis for instrument standardization. AOAC Method 990.03— combustion analysis—was the reference procedure. Standardization consisted of performing one of the following treatments to the instrument manufacturer's (or federal agency's) PC equation: (1) bias correction, (2) slope and intercept correction, or (3) recalibration with inclusion of standardization sample spectra. Standardized equations were then applied to a test set of 12 unknown HRW wheat sample spectra, with 2 samples blindly duplicated. The PCs of test samples ranged from 9 to 16%. Near-IR predictions were compared with reference measurements. Averaged within instrument type, root mean square of differences were 0.22, 0.24, 0.25, and 0.26% PC, depending on instrument. Corrected for bias within the test set, standard errors became 0.22, 0.18, 0.21, and 0.24% PC, respectively. These values were approximately twice the estimated lower limit for error (representing sample inhomogeneity). Overall repeatability relative standard deviation (RSD,) values were 0.92, 0.36, 0.42, and 0.74%, respectively. Overall reproducibility relative standard deviation (RSDR) values were 1.15, 0.61,1.53, and 1.38%. Such values for within-laboratory and between-laboratory variations of the near- IR methods were equivalent to values reported for the combustion method (990.03) for wheat. An inhouse study that examined all 6 U.S. wheat classes with one of the 4 instrument types produced repeatability and reproducibility values similar to those of the collaborative study, suggesting that the near-IR technique may be applied to red, white, hard, soft, and durum wheats. The near-IR method for determination of PC of whole-grain wheat has been adopted First Action (997.06) by AOAC INTERNATIONAL.
Stable Carbon Isotope Ratio Analysis of Honey: Validation of Internal Standard Procedure for Worldwide Application
Authors: White Jonathan W , Winters Kenneth , Peter Martin , Rossmann Andreas
Published: February 2020

abstract

Stable carbon isotope ratio analysis (SCIRA) of honey for undeclared presence of cane or corn sugars has been available for 20 years. Its use with domestic and imported honeys is reviewed. Six years of data from the internal standard isotope ratio analysis (ISCIRA) method support its worldwide validity for honey analysis. The ISCIRA database of pure honeys has been increased from 64 U.S. samples to 224 by addition of data from Germany, United Kingdom, Mexico, Italy, and Spain. ISCIRA analyses of 131 commercial honeys from the United States, Mexico, and Spain found that 17 are adulterated. Analyses of 303 Chinese honeys proves that they should have carbon isotope values similar to honeys from other areas, contrary to claims that the observed differences are intrinsic because of the variability of environmental conditions and of plants used in honey production in China. Addition of corn or cane (C4) sugars to honeys in amounts that do not produce a δ13C value greater than -23.5%o for the mixture cannot be detected by the original 1978 SCIRA procedure. Such adulteration however is detected by ISCIRA procedure from the δ13C value of the protein contained in the honey, which shows the isotopic composition of the honey before addition of C4 sugars. Fortythree percent of 98 honeys received in the United States in 1994-1997 with δ13C < -23.5%o were suspected and found to be adulterated.
Liquid Chromatographic Determination of Methylxanthines and Catechins in Herbal Preparations Containing Guaraná
Authors: Carlson Marvin , Thompson Richard D
Published: February 2020

Herbal preparations derived from the dried seeds of guarana (Paullinia cupana) have become a popular nutritional supplement used for stimulatory purposes. Once considered a drug substance in the United States, guaraná currently is classified as a food additive and dietary supplement. The pharmacological activity of guaraná-containing products is primarily due to methylxanthine alkaloids. For guaraná preparations, methylxanthine levels and, more significantly, the presence of several polyphenol compounds (i.e., catechins) provide phytochemical markers of authenticity. Methylxanthines and polyphenols are extracted from sample matrix with a heated phosphate buffer-methanol solution, the cooled extract is filtered, and the extract is injected into the liquid chromatographic (LC) system. A Nova-Pak C18 column eluted with phosphate buffer-methanol mobile phase (pH = 3.50) and monitored at 272 nm gave satisfactory resolution for the methylxanthines theobromine, theophylline, caffeine and the polyphenols (+)-catechin and (−)-epicatechin. Twenty-four products including dried seeds, dried paste, seed powders, tablets, and capsule formulations were assayed and conclusions were drawn about their authenticity. The LC system responded linearly to methylxanthines over the 100-fold range in concentration from 0.043 to 4.30 μg/mL for theobromine and caffeine and from 0.041 to 4.10 μg/mL for theophylline. Precision data for the 3 methylxanthines obtained from 10 different products (n = 5) gave relative standard deviation (RSD) values of 1.18-15.52% within a concentration range of 0.01-52.28 mg/g. Recoveries of methylxanthines from fortified products varied from 87.5 to 120.0%. The response for catechins was linear over a 200-fold range in concentration of 0.05-10.0 μg/mL. Precision data from 5 products (n = 5) gave RSD values of 1.08-5.54% within a concentration range of 0.34-32.65 mg/g. Recoveries from these products ranged from 87.7 to 109.7%. Results and chromatographic profiles for 14 commercial products in solid dosage form indicate that a number of these products may not contain authentic guaraná as an active ingredient or contain less than the declared quantity of guaraná. The proposed procedure also was applied to 2 carbonated soft drinks and a sample of mate.