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At least 739 records · Page 41Linked to original sources
PubMed2003

Human exposure to dioxins through the diet in Catalonia, Spain: carcinogenic and non-carcinogenic risk.

The main objectives of this study were to estimate the dietary intake of dioxins by the population of Catalonia, Spain, to determine which food groups showed the greatest contribution to this intake, and to assess the health risks potentially associated with the dietary dioxin intake. From June to August 2000, food samples were randomly acquired in seven cities of Catalonia. Dioxin concentrations were determined in 108 samples belonging to the following groups: vegetables, fruits, pulses, cereals, fish and shellfish, meats and meat products, eggs, milk and dairy products, and oils and fats. Estimates of average daily food consumption were obtained from recent studies. Total dietary intake of dioxins for the general population of Catalonia was estimated to be 95.4 pg WHO-TEQ/day (78.4 pg I-TEQ/day), with fish and shellfish (31%), diary products (25%), cereals (14%) and meat (13%) showing the greatest percentages of contribution to dioxin intake. The contribution of all the rest of food groups to the total dietary intake was under 20%. The non-carcinogenic risk index of dioxin intake through the diet was in the range 0.34-1.36, while the carcinogenic risk level was 1,360 excess cancer over a lifetime of 70 years. Our results corroborate the decreasing tendency in dietary intake of dioxins found in recent studies (2000-2001) from various countries.

Carcinogens, Environmental↗
PubMed1997

Amperometric bienzymic sensor for aspartame.

An amperometric enzyme electrode for the determination of aspartame was developed by covalent immobilization of alcohol oxidase and alpha-chymotrypsin. A platinum based hydrogen peroxide electrode was used as the detector. Excellent sensitivity was obtained using batch, flow-through and flow injection methods with detection limits of 2 x 10(-7), 4 x 10(-7) and 10(-6) mol l-1, respectively. Different strategies for eliminating interfering compounds, including the introduction of an additional alcohol oxidase-catalase membrane and signal subtraction using an alcohol electrode, were employed. A recovery study on seven food samples was carried out and the results were satisfactory.

Aspartame↗
PubMed2005

Development of a new oligonucleotide array to identify staphylococcal strains at species level.

The genus Staphylococcus is made up of 36 validated species which contain strains that are pathogenic, saprophytic, or used as starter cultures for the food industry. An oligonucleotide array targeting the manganese-dependent superoxide dismutase (sodA) gene was developed to overcome the drawbacks of the conventional methods of identification. Divergences of the sodA gene were used to design oligonucleotide probes, and we showed that each of the 36 species had a characteristic pattern of hybridization. To evaluate the array, we analyzed 38 clinical and 38 food or food plant Staphylococcus isolates identified by the phenotype-based system VITEK 2 (bioMérieux). This commercial kit failed to identify 8 (21%) of the clinical isolates and 32 (84%) of the food and food plant isolates. In contrast, the oligonucleotide array we designed provided an accurate and rapid method for the identification of staphylococcal strains, isolated from clinical, environmental, or food samples, at species level.

Bacterial Proteins↗
PubMedDate not supplied

Comparison of visual immunoassay and chromogenic culture medium for the presence of Listeria spp. in foods.

Two rapid screening methods [the TECRA Listeria Visual Immunoassay (LIS-VIS) kit, an AOAC-approved 48 h visual test, which detects Listeria through colorimetry, and BCM Listeria isolation and differentiation plating agar] were used to screen U.S. Food and Drug Administration-regulated commodities for the presence of Listeria spp. Seventy-four different food samples were screened for the presence of Listeria spp. by using both protocols. Test results for the TECRA LIS-VIA showed 66 negative samples and 1 false positive, with 4 confirmed as L. monocytogenes and 3 as L. innocua. With the BCM agar, 67 samples were negative, 4 were confirmed as L. monocytogenes, and 3 were confirmed as L. innocua. Both methods showed similar results and were effective screening tools for Listeria spp. in foods. The BCM agar method proved to be a rapid, sensitive, and excellent tool for early screening and differentiation of Listeria spp. present in foods.

Coloring Agents↗
PubMed2001

A quantitative stable-isotope LC-MS method for the determination of folic acid in fortified foods.

A stable-isotope liquid chromatography-mass spectrometry (LC-MS) assay was developed for the quantitative determination of folic acid in fortified foods. Folic acid was extracted from food samples into a phosphate buffer, purified on a C-18 Sep-Pak cartridge, and analyzed by LC-MS in the negative ion mode using electrospray ionization. The analyte was quantified using (13)C(5)-folic acid as an internal standard. The coefficient of variation for the precision of the method was 5.6% based on the analysis of four sample replicates. The accuracy of the method was assessed using a standard method of addition of folic acid to a shredded whole-wheat cereal. The quantitative determination of folic acid in this matrix was linear over 1 order of magnitude having a concentration range of 2.4 to 24 microg/g of food (or 0.05 to 0.5 microg of analyte injected into the LC-MS). The overall quantitative efficiency of the method was evaluated using a standard reference material (infant formula SRM 1846). The method was applied to the determination of folic acid in several test samples (fortified breakfast cereals), and the values were in accord with the manufacturer's claim. This method advances a LC-MS technique for the determination of folic acid in fortified foods based on stable-isotope dilution methodology. The specificity of the technique and quantitative accuracy of the method in various food substrates suggests that the method may be adapted for routine analysis in other fortified foods.

Avena↗
PubMed2003

Evaluation of conventional and organic italian foodstuffs for deoxynivalenol and fumonisins B(1) and B(2).

Two lots of human foodstuffs from conventional and organic brand foods were purchased from supermarkets and analyzed for three Fusarium toxins, deoxynivalenol, by GC-ECD, and fumonisins B(1) and B(2) (FB(1)-FB(2)), by LC-MS. The occurrence of deoxynivalenol contamination was higher than 80% in both organic and conventional foods; fumonisin B(1) was found in 20% of organic foods and in 31% of conventional ones and fumonisin B(2) in more than the 32% of the food samples from both the agricultural practices. The highest median concentration of deoxynivalenol occurred in conventional rice-based foodstuffs (207 microg/kg): that of fumonisin B(1) in conventional maize-based foods (345 microg/kg) and that of fumonisin B(2) in organic wheat-based foods (210 microg/kg).

Food Analysis↗
PubMed1998

Polystyrene cups and containers: styrene migration.

The level of styrene migration from polystyrene cups was monitored in different food systems including: water, milk (0.5, 1.55 and 3.6% fat), cold beverages (apple juice, orange juice, carbonated water, cola, beer and chocolate drink), hot beverages (tea, coffee, chocolate and soup (0.0, 0.5, 1, 2, and 3.6% fat), take away foods (yogurt, jelly, pudding and ice-cream), as well as aqueous food simulants (3% acetic acid, 15, 50, and 100% ethanol) and olive oil. Styrene migration was found to be strongly dependent upon the fat content and storage temperature. Drinking water gave migration values considerably lower than all of the fatty foods. Ethanol at 15% showed a migration level equivalent to milk or soup containing 3.6% fat. Maximum observed migration for cold or hot beverages and take-away foods was 0.025% of the total styrene in the cup. Food simulants were responsible for higher migration (0.37% in 100% ethanol). A total of 60 food samples (yogurt, rice with milk, fromage, biogardes, and cheese) packed in polystyrene containers were collected from retail markets in Belgium, Germany, and the Netherlands. The level of styrene detected in the foods was always fat dependent.

Beverages↗
PubMed2004

[Tyrophagus putrescentiae predating adult insects of Aedes aegypti and Aedes albopictus in laboratory].

The present study aimed at identifying a mite infesting a colony of Aedes aegypti and Ae. albopictus as well as investigating the source of infestation. The mite species was identified after it was mounted on slides in Hoyer's medium and examined under an optical microscope. It showed to be Tyrophagus putrescentiae. Fish and rabbit food samples were kept in an environmental chamber at 27 degrees C and 90% humidity for 21 days and were weekly examined. The presence of T. putrescentiae was only observed in rabbit food. It is assumed that T. putrescentiae had been introduced into the colonies through phoresy among guinea pigs, which were kept at the time near the insectary under favorable conditions for their development (28.7 degrees C, 72% humidity, photoperiod of 14L:10D hours).

Aedes↗
PubMed1984

[Occurrence and identification of enterotoxin-producing E. coli strains in milk and dairy products].

Enteric diseases caused by enterotoxigenic E. coli strains (ETEC) become more and more important all over the world. Frequently food is implicated as a vector. --From this the necessity arises to identify ETEC strains and/or their heatlabile (LT) and heat-stable enterotoxins (ST). The examinations carried out for the presented paper showed the following results: Detection of LT by coagglutination is a simple and rapid test and may be helpful for screening. Most suitable, however, is the application of ELISA which enables the detection of 1 ng/ml LT with a good reproducibility. For identification of ST the suckling mouse assay (SMA) yields reliable results. ELISA and SMA have proved to be useful in practice for examination of food samples. By means of these methods 157 E. coli strains predominantly isolated from milk and milk products were examined. Hereby, five ETEC strains could be identified (3.2%). For the purpose of food examination a procedure was developed which ensures a reliable and efficient identification of E. coli enterotoxin. The essential steps are enrichment in E.E.-broth, subcultivation in CAYE-2-broth, identification of LT by ELISA resp. coagglutination and the detection of ST with aid of the SMA. So, isolation of single colonies can be omitted, which is an essential advantage.

Agglutination Tests↗
PubMed1996

[Mercury determination in food of plant origin by cole vapour atomic absorption spectrometry (CVAAS)].

The studies on the analytical procedure for mercury determination in food of plant origin on the level of 5 micrograms/kg, were carried out. For this reason, microwave digestion with HNO3 and cold vapour atomic absorption spectrometry (CVAAS) with tin (II) chloride reduction, were used. Both digestion and determination conditions were experimentally optimized. The procedure was checked using two real food samples: apple juice and preserved carrot with peas both spiked on two levels with mercury. On these results basic statistic parameters that characterized the method as standard deviation, relative standard deviation and recovery, were calculated. The precision was generally better than 10%, and recovery ranged from 96 to 100%. The detection limit of the entire procedure, defined as the mercury concentration corresponding to three times the standard deviation of ten consecutive determinations of blank measurement, was 0.012 microgram/l. Taking into account the amount of a sample and the factor of dilution the detection limit corresponds to 0.3 microgram/kg for 1.0 g, 1.0 microgram/kg for 0.3 g, and 0.15 microgram/l for 2 ml of a sample. Accuracy of the analytical procedure was tested by analysing five certified reference plant materials with the mercury contents ranged from 6 to 280 micrograms/kg. The obtained results were in a good agreement with their certified values. Both analyses of the spiked real samples and certified reference materials allow to suggest that this analytical procedure based on microwave digestion and cold vapour determination using Fully Automated Mercury System is suitable for mercury determination in food products of plant origin on the level of microgram/kg or microgram/l, with a good precision and accuracy.

Mercury↗
PubMed2006

Analysis of prominent flavonoid aglycones by high-performance liquid chromatography using a monolithic type column.

A fast RP-HPLC method for the simultaneous separation of eleven main flavonoid aglycones in food samples was developed. Flavonoids were divided in three groups according to their hydrophobicity and were resolved by a ternary gradient elution and diode array detection within analysis times less than 15 min. The detection limits of the flavonoids studied were in the range between 0.04 and 0.31 microg/mL, with repeatabilities values between 0.4 and 5%. The method was successfully applied to the analysis of these compounds in complex natural samples, like propolis and Ginkgo biloba.

Acetonitriles↗
PubMed1999

Bioassays for the detection of growth-promoting agents, veterinary drugs and environmental contaminants in food.

Residues of growth-promoting agents, veterinary drugs and environmental contaminants in food products are routinely analyzed with chemical-analytical methods, using physical and spectrometric properties of a compound. Since residue limits are in general based on biological properties of compounds, bioassays offer in theory a good alternative. As a consequence, these assays are much more suitable for the detection of mixtures of compounds with common biological properties, including possibly unknown agonists. Using modern molecular biological techniques, a new generation of bioassays has been developed, showing in general a higher sensitivity and specificity for the target compounds. The CALUX (chemical activated luciferase expression) assay was developed for the detection of polyhalogenated compounds, based on their affinity for the aryl hydrocarbon (Ah) receptor. This paper focuses on the specificity of the assay. The benzimidazole compounds oxfendazole, fenbendazole, febantel, thiabendazole, mebendazole, omeprazole, lanzoprazole and benomyl were shown to give a positive response in the assay. Similar results were obtained with dexamethasone, corticosterone and cortisol, which in addition were able to enhance the response obtained with TCDD. Similarly to the flavonoids alpha- and beta-naphtoflavone, the reported Ah receptor antagonist 4-amino-3-methoxyflavone showed a strong positive response at a concentration of 400 microM, but failed to inhibit the response obtained with TCDD. It is concluded that the chances of false-negative results appear to be minimal and can be recognized. False-positive or, better, unwanted results are in theory more likely to occur. Possible solutions to avoid or detect these type of results are discussed. In general, these kinds of assays offer great possibilities for screening of food samples. In addition to the further optimization of these assays, future work should be focused on the development of rapid, sample and selective extraction procedures.

Animals↗
PubMed1969

Lead poisoning in Gurkha soldiers in Hong Kong.

Investigation of an outbreak of lead-poisoning in 121 Gurkha soldiers showed that this was due to the contamination of chilli powder (cayenne pepper), a constituent of curry powder, with lead chromate. Comprehensive systems of food sampling are needed in developing communities.

Anemia↗
PubMedDate not supplied

[Identification of the mycotoxin zearalenone in Argentina].

Zearalenone, an estrogenic toxin produced by several Fusarium sp., was detected by two chromatographic methods in grain and food samples from several farms of th Buenos Aires Province. Suspected zearalenone spots were identified by comparing their Rf against that of the pure substance, by their change of behaviour under ultraviolet light of different wavelengths, by comparing the Rf against a standard preparation after thin layer chromatography in four different solvent systems, and by color reactions obtained after spraying reagents on the thin layer chromatographic plates. Sixteen of 55 samples were positive, with concentrations of the toxin ranging from 200 ppb to 750 ppb. Only Fusarium graminearum was isolated from eleven of these samples, indicating that the fungus was inactivated by heat or antifungal treatments.

Argentina↗
PubMed1981

Distinguishing common food-contaminating bat hairs from certain feather barbules.

Differences are described between common food-contaminating vespertilionid bat hairs (Chiroptera: Vespertilionidae) and similar-appearing downy feather barbules of passeriform birds, including cuticular scales, pigment distribution, and basal characteristics. Fifteen imported food samples analyzed over a 1 1/2 year period were contaminated with these bat hairs.

Animals↗
PubMed2006

Novel reference gene, PKABA1, used in a duplex real-time polymerase chain reaction for detection and quantitation of wheat- and barley-derived DNA.

We report the development of a duplex real-time Polymerase Chain Reaction (PCR) for the simultaneous detection and quantification of wheat- and barley-derived DNA. We used a single primer pair to amplify the single-copy gene PKABA1 from wheat and barley, using minor-groove-binding probes to distinguish between the two cereals. The assay was fully specific, and different wheat and barley cultivars exhibited similar Ct values, indicating stability across cultivars with respect to allelic and copy number composition. The limits of detection were 5 and 10 PCR-forming units for wheat and barley, respectively, making the duplex assay as sensitive as other singleplex reference gene systems published. We were able to detect both wheat and barley simultaneously in real food samples, and the duplex assay is considered to be suitable as an endogenous reference gene system for the detection and quantification of wheat and barley in genetically modified organisms (GMO) and other food and feed analyses.

DNA, Plant↗
PubMed1996

A comparison of immunomagnetic separation, direct culture and polymerase chain reaction for the detection of verocytotoxin-producing Escherichia coli O157 in human faeces.

Verocytotoxin-producing Escherichia coli O157 (O157 VTEC) has become well recognized as an important enteric pathogen. The number of organisms present in environmental and clinical samples may be low and efforts have been made to increase the sensitivity of O157 VTEC detection. Immunomagnetic seperation (IMS) has been shown to improve O157 VTEC detection in bovine faeces and food samples. A milkborne outbreak of O157 VTEC infection allowed us to compare the isolation rates from human faeces by IMS, direct faecal culture on sorbitol-MacConkey agar and a PCR test for verotoxin gene carriage. Of 142 faecal samples examined, 20 were positive on both direct culture and IMS and a further 13 on IMS alone. Therefore, IMS increased the detection rate of individual cases of O157 VTEC infection and also compared well with PCR. We recommend IMS for use in routine diagnostic laboratories where a more sensitive method than direct faecal culture is required for O157 VTEC isolation.

Animals↗