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Biomedical subjects

Elke Anklam

Publications and source records attributed to Elke Anklam.

At least 19 recordsLinked to original sources
PubMed2006

Collaborative trial validation study of two methods, one based on high performance liquid chromatography-tandem mass spectrometry and on gas chromatography-mass spectrometry for the determination of acrylamide in bakery and potato products.

A European inter-laboratory study was conducted to validate two analytical procedures for the determination of acrylamide in bakery ware (crispbreads, biscuits) and potato products (chips), within a concentration range from about 20 microg/kg to about 9000 microgg/kg. The methods are based on gas chromatography-mass spectrometry (GC-MS) of the derivatised analyte and on high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) of native acrylamide. Isotope dilution with isotopically labelled acrylamide was an integral part of both methods. The study was evaluated according to internationally accepted guidelines. The performance of the HPLC-MS/MS method was found to be superior to that of the GC-MS method and to be fit-for-the-purpose.

Acrylamide↗
PubMed2006

Investigation of the correlation of the acrylamide content and the antioxidant activity of model cookies.

The purpose of this study was to evaluate the correlation between the acrylamide (AA) content and the antioxidant activity (AOA) of self-prepared cookies. Cookies were baked in the laboratory under defined conditions following four different recipes. The parameters of investigation were the influence of the type and relative content of sugar (glucose and fructose) and the baking time on the AA content as well as AOA of the final products. Parameters depending on the recipe and baking conditions such as the moisture content, the total nitrogen concentration, and the color of the products were evaluated for all samples as well. To prove the transferability of the findings gained with model cookies to samples from industry, the same measurements were performed on seven different types/brands of cookies that were purchased in local markets. A direct correlation was found between the concentration of AA and the AOA. With increasing baking time, the moisture content of the cookies decreased. The latter parameter correlated well with the AA concentration and AOA. The use of fructose enhanced the concentration of AA and the AOA of the final products, when compared with the use of sucrose. However, a simple model for the prediction of acrylamide contents and the AOA of samples from the baking time, color, protein, or moisture content of the samples was not found.

Acrylamide↗
PubMed2005

Single-laboratory validation of a gas chromatography-mass spectrometry method for quantitation of 15 European priority polycyclic aromatic hydrocarbons in spiked smoke flavourings.

An existing method was adapted to the purpose and validated in-house according to the IUPAC harmonised guideline for the determination of 15 EU priority polycyclic aromatic hydrocarbons (PAHs) in primary smoke condensates (PSCs) that are used to produce smoke flavourings for human consumption. Limits of detection (LOD) varied between 0.1 and 1.3 microg/kg, limits of quantitation (LOQ) between 0.5 and 4 microg/kg for the various PAHs in PSCs. The coefficient of variance of the repeatability was between 0.7% (benzo[a]pyrene) and 30% (dibenzo[a,h]pyrene) relative standard deviation, depending on the analyte. The recoveries varied between 100 and 102% (dibenzo[a,l]pyrene) and 69-83% (dibenzo[a,h]pyrene) over the analytical range of 5-35 microg/kg.

Benz(a)Anthracenes↗
PubMed2005

Semicarbazide: occurrence in food products and state-of-the-art in analytical methods used for its determination.

This review provides an overview of the information currently available about the presence of semicarbazide (SEM) in food. Likely sources of SEM in food matrices are summarised and discussed. Detailed information is given about the analytical methods used to determine SEM; features and drawbacks associated with them are carefully evaluated. Performance criteria characterising the analytical methods discussed are also given.

Animals↗
PubMed2005

Experimental design-based development and single laboratory validation of a capillary zone electrophoresis method for the determination of the artificial sweetener sucralose in food matrices.

A capillary zone electrophoresis (CZE) method, optimised chemometrically, underwent a complete in-house validation protocol for the qualification and quantification of sucralose in various foodstuffs. Separation from matrix components was obtained in a dinitrobenzoic acid (3 mM)/sodium hydroxide (20 mM) background electrolyte with a pH of 12.1, a potential of 0.11 kV cm(-1) and a temperature of 22 degrees C. Detection was achieved at 238 nm by indirect UV. Screening, optimisation and robustness testing were all carried out with the aid of experimental design. Using standard addition calibration, the CZE method has been applied to still, carbonated and alcoholic beverages, yoghurts and hard-boiled candy. The method allows the detection of sucralose at >30 mg kg(-1), with a linearity range of 50-500 mg kg(-1), making it suitable for implementation of the recently amended "Sweeteners for use in foodstuffs" Directive (European Parliament and Council (2003) Off J L237:3-12), which set maximum usable doses of sucralose for many foodstuffs, most ranging from 200 mg kg(-1) to 450 mg kg(-1).

Beverages↗
PubMed2005

Composition and analysis of liquid smoke flavouring primary products.

Smoke flavourings are produced on a large scale and have been applied to a variety of food products for more than 30 years. The use of them has many advantages compared to traditional smoking techniques. Among others, the amount of (known) toxic compounds deriving from combustion processes can be more easily controlled in smoke flavourings. In order to ensure safe products, a new European Regulation requests data on the composition and lays down, in particular, the maximum permitted concentrations for selected polycyclic aromatic hydrocarbons (PAHs). This review compiles results published on the chemical composition of liquid smoke flavouring primary products, partly in relation to production process parameters, and the analytical methods involved. The methods cover chromatographic techniques for analysis of specific compounds including extraction methods and clean-up procedures. Analysis of sensorial and bulk parameters such as acidity and total phenolic compounds are described as well as they are used as standard methods for analysis of liquid smoke flavourings. A special section is devoted to discussing the analysis of PAHs.

Chromatography, Gas↗
PubMed2004

Cluster analysis for the systematic grouping of genuine cocoa butter and cocoa butter equivalent samples based on triglyceride patterns.

The triglyceride profile of cocoa butters (CBs) from different geographical origins, varieties, growing seasons, and a number of cocoa butter equivalents (CBEs) was determined by capillary gas liquid chromatography. Hierarchical cluster analysis was applied to the five main triglycerides of the samples for the ability to find natural groupings among (a) CBs of various provenance and (b) CBE samples of different types. The samples were clustered using Ward's method, and the similarity values of the linkages were represented by dendrograms. The five triglycerides contained adequate information to obtain a meaningful sample differentiation. This information can be used to assess the purity and the origin of the CB sample examined.

Chromatography, Gas↗
PubMed2004

Interlaboratory evaluation of injection techniques for triglyceride analysis of cocoa butter by capillary gas chromatography.

As part of two international collaborative studies, in which 14 laboratories applied capillary GLC to determine the triglyceride (TG) profile of cocoa butter, the performance of different sample introduction techniques, i.e. cold on-column injection (OCI), split injection and programmed-temperature vapouriser (PTV) injection, was compared. In both studies, the participants did not apply a uniform GLC procedure. Synthetic mixtures of triglycerides were chosen to permit an accurate determination of detector response factors. No statistically significant difference was found between the mean values obtained by different injection modes. The OCI, generally recommended as best practice, did not give superior results than the PTV or the split injection techniques.

Chromatography, Gas↗
PubMed2004

Evaluation of the results from an inter-laboratory comparison study of the determination of acrylamide in crispbread and butter cookies.

Analytical methods currently employed for determination of acrylamide (AA) in two carbohydrate-rich food samples, crispbread and butter cookies, obtained commercially, and native and spiked bread extract samples have been evaluated in a collaborative study. The objective of the study was to obtain information about the performance of the participating laboratories when analysing samples with an AA content close to the limit of quantification ( LOQ) and at a higher AA level, and to investigate the influence of sample-preparation procedures on the results of the analysis. For this purpose an aqueous native extract of white bread crumb, a fortified extract, and AA standard solutions, the analyte content of which were not disclosed to the participants, were included in the study. A total of 62 laboratories, applying seven different measurement techniques and a broad spectrum of analyte extraction and sample-preparation procedures reported their analytical results. Because the measurement data were not normally distributed, they were evaluated by application of robust statistics. The relative performance of the laboratories was highlighted by calculation of z-scores. For the crispbread sample, especially, a large percentage of the calculated z-scores were outside the satisfactory range. From their distribution it became obvious that one of the analytical techniques might be biased, if not applied correctly. Consequently, the impact of the applied methods was examined in more detail. Information about the analytical technique, extraction solvent, quantity weighed, calibration method, clean-up, and the experience of the participating laboratories were extracted from the analytical protocols and transcribed into a data matrix which was evaluated by multifactor analysis of variance. The applied measurement technique seems to have a statistically significant influence on the analytical results.

Journal Article↗
PubMed2004

Effect of roasting history and buffer composition on peanut protein extraction efficiency.

Peanut is a major allergenic food. Undeclared peanut (allergens) from mis-formulation or contamination during food processing pose a potential risk for sensitized individuals and must be avoided. Reliable detection and quantification methods for food allergens are necessary in order to ensure compliance with food labelling and to improve consumer protection. The extraction of proteins from allergenic foods and complex food products is an important step in any allergen detection method. In this study, the protein extraction efficiency of various buffers prepared in-house and some extraction buffers included in some commercial allergen enzyme-linked immunosorbent assay (ELISA) test kits for peanut determination in food products were tested. In addition, the effect of roasting history on the extractability of peanut protein was investigated by the biuret and the bicinchoninic acid (BCA) assays. Elevated roasting temperatures in food processing were found to have a major impact on protein extraction efficiency by reducing protein yields of oil and dry roasted peanuts by 50-75% and 75-80%, respectively, compared with the raw material. Extraction buffers operating in the higher pH range (pH 8-11) showed best yields.

Allergens↗
PubMed2003

In-house validation of an improved sample extraction and clean-up method for GC determination of isomers of nervonic acid in meat products.

An improved extraction and clean-up method for determination of brain-specific fatty acids, in particular lignoceric acid (C24:0) and the cis/ trans isomers of nervonic acid (15 c-t C24:1), in meat products has been developed. The method is based on isolation of the polar lipids of interest from the bulk lipids by solid-phase extraction. The fatty acids, derivatised to their fatty acid methyl esters, are quantified by GC in a DB5 column. Fresh meat samples were extracted by using a mixture of n-butanol:hexane (1:9) as solvent. The extract was loaded in a silica gel cartridge column previously equilibrated with hexane. The first fraction containing the major part of the fat was eluted with hexane while acetone and methanol allowed the elution of fatty acids bound to polar moieties such as nervonic and lignoceric acids. This second fraction containing the analyte was methylated and injected into the GC for quantification after addition octacosane (C(28)) as internal standard.

Animals↗
PubMed2003

Assessment of dietary exposure to some persistent organic pollutants in the Republic of Karakalpakstan of Uzbekistan.

A 1999 study heightened long-standing concerns over persistent organic pollutant contamination in the Aral Sea area, detecting elevated levels in breast milk and cord blood of women in Karakalpakstan (western Uzbekistan). These findings prompted a collaborative research study aimed at linking such human findings with evidence of food chain contamination in the area. An international team carried out analyses of organochlorine and organophosphate pesticides, polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs) on samples of 12 foods commonly produced and consumed in Karakalpakstan. Analysis consistently detected long-lasting organochlorine pesticides and their metabolites in all foods of animal origin and in some vegetables such as onions and carrots--two low-cost components of many traditional dishes. Levels of PCBs were relatively low in all samples except fish. Analyses revealed high levels of PCDDs and PCDFs (together often termed "dioxins") in sheep fat, dairy cream, eggs, and edible cottonseed oil, among other foodstuffs. These findings indicate that food traditionally grown, sold, and consumed in Karakalpakstan is a major route of human exposure to several persistent toxic contaminants, including the most toxic of dioxins, 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD). Intake estimations demonstrate that consumption of even small amounts of locally grown food may expose consumers to dioxin levels that considerably exceed the monthly tolerable dioxin intake levels set by the World Health Organization. Data presented in this study allow a first assessment of the risk associated with the consumption of certain food products in Karakalpakstan and highlight a critical public health situation.

Dioxins↗
PubMed2003

A competitive polymerase chain reaction-based approach for the identification and semiquantification of mitochondrial DNA in differently heat-treated bovine meat and bone meal.

The risk of bovine spongiform encephalopathy propagation was drastically reduced after the European Union (EU) Health Authorities adopted restrictions involving a ban on animal-derived proteins in the diet of farm animals. Currently, the EU's officially recommended method for controlling meat and bone meal (MBM) in animal feed is the microscopic method, which involves the identification of bone fragments on the basis of their morphological characteristics. Recently, we demonstrated that a polymerase chain reaction (PCR)-based assay can be used for the detection of taxon-specific DNA in MBM and animal feeds. To ensure the safe rendering of animal by-products, the EU Council requires that this material be treated at 133 degrees C at 300 kPa for 20 min. Here we investigate the relationship between DNA degradation, PCR amplification, and MBM heat treatment. With a competitive PCR-based approach, we compare the amplification efficiency of bovine mitochondrial DNA target sequences of different lengths in several heat-treated MBM samples. For our method, a synthetic competitive DNA is used as an internal control for both DNA extraction and PCR reaction. A correlation between an increase in treatment temperature and a reduction in the size of the target sequences suitable for amplification was observed, suggesting progressive DNA fragmentation due to the temperature. We show that short amplicons (147 bp) can be used to detect the presence of bovine mtDNA in MBM samples treated according to the current European regulations. The use of such a competitive approach to compare amplification efficiency levels of targets of different lengths might represent a useful tool for the determination of both the amount of MBM in animal feeds and its proper heat treatment.

Animal Feed↗
PubMedDate not supplied

Comparison of two post-column derivatization systems, ultraviolet irradiation and electrochemical determination, for the liquid chromatographic determination of aflatoxins in food.

This study compared 2 post-column derivatization (PCD) techniques for the determination of aflatoxins B1, B2, G1, and G2 (AFB1, AFB2, AFG1, and AFG2) by fluorescence detection after liquid chromatographic separation: ultraviolet (UV) irradiation (PCD(UV)) and electrochemical bromination (PCD(EC)). Photochemical fluorescence enhancement was obtained with 2 different commercially available systems (PCD(UV1) and PCD(UV2)). An electrochemical bromination apparatus was used for bromination. Analyses of naturally contaminated or spiked samples of corn, pistachio paste, peanut butter, fig paste, and animal feed showed that neither of the techniques resulted in derivatization-specific matrix interferences for any of the matrixes under study, even when extracts were not completely purified. The response ratios PCD(UV)/PCD(EC) for AFB1, AFB2, AFG1, and AFG2 were 0.86, 0.96, 0.70, and 0.96, respectively, for PCD(UV1) and 0.82, 0.95, 0.60, and 0.90, respectively, for PCD(UV2). The long-term use of the UV lamps (300 h for PCD(UV1) and 343 h for PCD(UV2)) in the photochemical detectors showed that these ratios remained stable throughout the time frame investigated. The relative standard deviation obtained for each of the devices during the in-house validation study ranged from 0.3 to 1.8% for PCD(UV1), from 0.8 to 1.3% for PCD(UV2), and from 0.9 to 2.0% for PCD(EC).

Aflatoxins↗
PubMedDate not supplied

Method development in relation to regulatory requirements for detection of GMOs in the food chain.

This is a summary report of a joint workshop held in Brussels, Belgium, in December 2000. The workshop was organized by the ILSI Europe Novel Food Task Force in collaboration with the European Commission's Joint Research Centre (JRC) and ILSI International Food Biotechnology Committee. The purpose was to investigate progress in the development of analytical methods since the last workshop was held in June 1998.

Crops, Agricultural↗
PubMedDate not supplied

Analytical challenges: bridging the gap from regulation to enforcement.

An overview is presented of the analytical steps that may be needed to determine the presence of genetically modified organisms (GMOs) or for analysis of GMO-derived produce. The analytical aspects necessary for compliance with labeling regulations are discussed along with bottlenecks that may develop when a plant product or a food sample is analyzed for conformity with current European Union GMO legislation. In addition to sampling and testing, other topics deal with complications that arise from biological and agricultural realities that may influence testing capabilities. The issues presented are intended to serve as elements to examine the different challenges that enforcement laboratories might face.

Crops, Agricultural↗