Biomedical subjects

Elke Anklam

Publications and source records attributed to Elke Anklam.

29 records · Page 2Linked to original sources

PubMedDate not supplied

Immunoaffinity column cleanup with liquid chromatography using post-column bromination for determination of aflatoxin B1 in cattle feed: collaborative study.

A collaborative study was conducted to evaluate the effectiveness of an immunoaffinity column cleanup liquid chromatography (LC) method for determination of aflatoxin B1 in cattle feed at a possible future European regulatory limit (1 ng/g). The test portion was extracted with acetone-water (85 + 15), filtered, diluted with water, and applied to an immunoaffinity column. The column was washed with water to remove interfering compounds, and the purified aflatoxin B1 was eluted with methanol. Aflatoxin B1 was separated and determined by reversed-phase liquid chromatography (RP-LC) and detected by fluorescence after post column derivatization (PCD) involving bromination. PCD was achieved with either pyridinium hydrobromide perbromide (PBPB), used by 14 laboratories, or an electrochemical cell and addition of bromide to the mobile phase, used by 7 laboratories. Both derivatization techniques were not significantly different when compared by the t-test; the method was statistically evaluated for all laboratories together (bromination and PBPB). The cattle feed samples, both spiked and naturally contaminated with aflatoxin B1, were sent to 21 laboratories in 14 different countries (United States, Japan, and Europe). Test portions were spiked at levels of 1.2 and 3.6 ng/g for aflatoxin B1. Recoveries ranged from 74 to 157%. Based on results for spiked samples (blind pairs at 2 levels) as well as naturally contaminated samples (blind pairs at 3 levels), the relative standard deviation for repeatability (RSDr) ranged from 5.9 to 8.7%. The relative standard deviation for reproducibility (RSDR) ranged from 17.5 to 19.6%. The method showed acceptable within- and between-laboratory precision for this matrix, as evidenced by HORRAT values, at the target levels of determination for aflatoxin B1. No major differences in RSD were observed, showing that the composition of the feeds was not a factor for the samples tested and that the method was applicable for all materials used.

Aflatoxin B1↗

PubMedDate not supplied

Detection and quantification of cocoa butter equivalents in cocoa butter and plain chocolate by gas liquid chromatography of triacylglycerols.

The development and in-house testing of a method for the detection and quantification of cocoa butter equivalents in cocoa butter and plain chocolate is described. A database consisting of the triacylglycerol profile of 74 genuine cocoa butter and 75 cocoa butter equivalent samples obtained by high-resolution capillary gas liquid chromatography was created, using a certified cocoa butter reference material (IRMM-801) for calibration purposes. Based on these data, a large number of cocoa butter/cocoa butter equivalent mixtures were arithmetically simulated. By subjecting the data set to various statistical tools, reliable models for both detection (univariate regression model) and quantification (multivariate model) were elaborated. Validation data sets consisting of a large number of samples (n = 4050 for detection, n = 1050 for quantification) were used to test the models. Excluding pure illipé fat samples from the data set, the detection limit was determined between 1 and 3% foreign fat in cocoa butter. Recalculated for a chocolate with a fat content of 30%, these figures are equal to 0.3-0.9% cocoa butter equivalent. For quantification, the average error for prediction was estimated to be 1.1% cocoa butter equivalent in cocoa butter, without prior knowledge of the materials used in the blend corresponding to 0.3% in chocolate (fat content 30%). The advantage of the approach is that by using IRMM-801 for calibration, the established mathematical decision rules can be transferred to every testing laboratory.

Cacao↗

PubMedDate not supplied

Method validation for detection and quantification of cocoa butter equivalents in cocoa butter and plain chocolate.

A European interlaboratory study was conducted to validate an analytical procedure for the detection and quantification of cocoa butter equivalents in cocoa butter and plain chocolate. In principle, the fat obtained from plain chocolate according to the Soxhlet principle is separated by high-resolution capillary gas chromatography into triacylglycerol fractions according to their acyl-C-numbers, and within a given number, also according to unsaturation. The presence of cocoa butter equivalents is detected by linear regression analysis applied to the relative proportions of the 3 main triacylglycerol fractions of the fat analyzed. The amount of the cocoa butter equivalent admixture is estimated by partial least-squares regression analysis applied to the relative proportions of the 5 main triacylglycerols. Cocoa butter equivalent admixtures were detected down to a level of 2% related to the fat phase, corresponding to 0.6% in chocolate (assumed fat content of chocolate, 30%), without false-positive or -negative results. By using a quantification model based on partial least-squares regression analysis, the predicted cocoa butter equivalent amounts were in close agreement with the actual values. The applied model performed well at the level of the statutory limit of 5% cocoa butter equivalent addition to chocolate with a prediction error of 0.6%, assuming a chocolate fat content of 30%.

Cacao↗

PubMedDate not supplied

Polymerase chain reaction techniques for food allergen detection.

Food allergies represent an important health problem in industrialized countries. Undeclared allergenic foods as contaminants in food products pose a major risk for sensitized persons. Reliable detection and quantification methods for food allergens are necessary to ensure compliance with food labeling and improve consumer protection. The methods currently used for the detection of potential allergens in foods are to target either the allergen itself or a marker that indicates the presence of the offending food. As markers for the presence of potentially allergenic foods or ingredients, specific proteins or DNA fragments are targeted. In routine food analysis, the enzyme-linked immunosorbent assay (ELISA) and the polymerase chain reaction (PCR) in the form of a real-time PCR or in combination with an ELISA have been used. The availability, the characteristics, and some future aspects of DNA-based methods in the rapid and sensitive detection of potentially allergenic food constituents or contaminations are discussed in this review.

Allergens↗

PubMedDate not supplied

Effects of chemical, physical, and technological processes on the nature of food allergens.

A review is presented of studies of different processing techniques and their effect on the allergenicity and antigenicity of certain allergenic foods. An overview of investigated technologies is given with regard to their impact on the protein structure and their potential application in the production of hypoallergenic foods. The use of physical processes (such as heating, high pressure, microparticulation, ultrafiltration, and irradiation), chemical processes (such as proteolysis, fermentation, and refining by extraction), and biotechnological approaches, as well as the effects of these processes on individual allergenic foods, are included. Additionally, the implications of food processing for food allergen analysis with respect to food safety assessment and industrial quality control are briefly discussed.

Allergens↗

PubMedDate not supplied

Overview of acrylamide monitoring databases.

Since high acrylamide levels in carbohydrate-rich food were reported in 2002, many research activities were started in order to gain knowledge on occurrence, formation, and prevention of this compound in food products. Among them, monitoring programs were conducted in many countries worldwide by official bodies as well as by the food industry. National and international bodies set up monitoring databases. In 2003, both the European Commission and the World Health Organization posted calls for data and placed their spreadsheets for the submission of data on the Web. The goal of the databases is to collect data for a reliable estimation of the exposure of consumers to acrylamide via the food chain. This paper describes the assessment of the data quality and outlines the composition of the data in the 2 databases, to date.

Acrylamide↗

PubMedDate not supplied

Results from two interlaboratory comparison tests organized in Germany and at the EU level for analysis of acrylamide in food.

After the publication of high levels of acrylamide (AA) in food, many research activities started all over the world in order to determine the occurrence and the concentration of this substance in various types of food. As no validated methods were available at that time, interlaboratory studies on the determination of AA in food were of the highest priority. Under the boundary conditions of applying well-established evaluation schemes, the results of 2 studies conducted by the Federal Institute for Risk Assessment (BfR) in Germany and by the European Commission's Directorate General Joint Research Center (JRC) exhibited an overall acceptable performance of the participants in these studies. Nevertheless, many laboratories showed problems in determining AA in food with a complex matrix such as cocoa. The results of analysis also showed a broader variation of AA for samples with low AA concentrations and indicated a bias of the results obtained by gas chromatography-mass spectrometry without derivatization. Improvements of the performance of some laboratories appeared to be necessary.

Acrylamide↗

PubMedDate not supplied

Liquid chromatographic method for quantitation of patulin at 10 ng/mL in apple-based products intended for infants: interlaboratory study.

An interlaboratory trial for the determination of patulin in apple juice and fruit puree was conducted, involving 17 participants representing a cross section of industry, official food control, and research facilities. Mean recoveries reported ranged from 74 (10 ng/g) to 62% (25 ng/g) for apple juice and from 72 (25 ng/g) to 74% (10 ng/g) for fruit puree. Based on results for spiked samples (blind pairs at 2 levels), as well as naturally contaminated samples (blind pairs at 3 levels), the relative standard deviation for repeatability (RSDr) in juice ranged from 8.0 to 14.3% and in puree from 3.5 to 9.3%. The relative standard deviation for reproducibility (RSD(R)) in juice ranged from 19.8 to 39.5% and in puree from 12.5 to 35.2%, reflecting HORRAT values from 0.6 to 1.0 for juice and 0.4 to 0.9 for puree. The method showed acceptable within-laboratory and between-laboratory precision for each matrix, as required by current European legislation.

Beverages↗

PubMedDate not supplied

Evaluation of results of an interlaboratory comparison test on determination of acrylamide in crispbread samples.

The European Commission's Directorate General Joint Research Centre has organized several proficiency tests on the determination of acrylamide (AA) in food. This paper presents the results and outcome of a proficiency test that focused on the determination of AA in crispbread samples. One of the goals was the identification of the influence of different parameters such as analyte extraction or instrument calibration on the analytical results. A set of samples, containing 3 different crispbread samples as well as extracts of one crispbread sample and AA standard solutions, was shipped to each participant. A total of 42 European laboratories reported analytical results that were evaluated by applying internationally accepted protocols and procedures. The study found that, for each sample, the results of 4-8 laboratories were outside the range formed by the target value plus or minus the 2-fold of the target standard deviation; thus, they did not perform satisfactorily. In transferring this knowledge to the data of monitoring databases of AA in food, care must be taken that data are quality controlled, as it is likely that some of them may be biased.

Acrylamide↗

PubMedDate not supplied

Validation of two commercial lateral flow devices for the detection of peanut proteins in cookies: interlaboratory study.

Results are reported for an interlaboratory validation study of 2 commercially available Iateral flow devices (dipstick tests) designed to detect peanut residues in food matrixes. The test samples used in this study were cookies containing peanuts at 7 different concentrations in the range of 0-30 mg peanuts/kg food matrix. The test samples with sufficient and proven homogeneity were prepared in our laboratory. The analyses of the samples (5 times per level by each laboratory) were performed by 18 laboratories worldwide which submitted a total of 1260 analytical results. One laboratory was found to be an outlier for one of the test kits. In general, both test kits performed well. However, some false-negative results were reported for all matrixes containing < 21 mg peanuts/kg cookie. It must be stressed that the test kits were challenged beyond their cut-off limits (> or = 5 mg/kg, depending on the food matrix). One test kit showed fewer false-negative results, but it led to some false-positive results for the blank materials. The sensitivity of the dipstick tests approaches that achieved with enzyme-linked immunosorbent assays.

Arachis↗

PubMedDate not supplied

Method validation for determination of the 15 European-priority polycyclic aromatic hydrocarbons in primary smoke condensates by gas chromatography/mass spectrometry: interlaboratory study.

A collaborative study was conducted to validate an analytical method for quantification of the 15 polycyclic aromatic hydrocarbons (PAHs) regarded in 2002 as a health concern by the former Scientific Committee on Food of the European Commission (SCF) in primary smoke condensates. The method is based on gas chromatography/mass spectrometry of a cyclohexane extract with solid-phase cleanup through silica gel. The analytes were detected in the selected-ion monitoring mode and quantified by using 3 isotopically labeled internal standard compounds. Seventeen laboratories participated in the collaborative validation study, of which 12 reported valid results. The data were subjected to Cochran, single Grubbs, and double Grubbs tests for statistical outliers. A maximum of 2 outliers was eliminated before further statistical evaluation of the method performance characteristics. Depending on the analyte, the results showed relative standard deviations for repeatability between 4.2 and 30% and for reproducibility from 9.9 to 60%. The recoveries varied between about 50 and 85%, except those for cyclopenta[cd]pyrene, dibenzo[a,l]pyrene, and dibenzo[a,h]pyrene. Nevertheless, because Commission Directive 2005/10/EC allows for a recovery range of 50-120% for (BaP) benzo[a]pyrene in various foods, it can be concluded that the method performs appropriately within the analytical range between 5 and 25 microg/kg of primary smoke condensate. For BaP the validated analytical range covered 5-20 microg/kg, and for benzo[a]anthracene (BaA) 10-25 microg/kg. The method is suitable for monitoring BaP and BaA at their respective maximum permitted levels of 10 and 20 microg/kg. Three analytes, benzo[b]-, benzo[j]-, and benzo[k]-fluoranthene could not be separated by all of the participants and were therefore treated as the sum. Nevertheless, with this method the pattern of the respective concentrations of these 15 PAHs can be monitored in primary smoke condensate as suggested by the SCF.

Chemistry Techniques, Analytical↗