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PubMed2002

Assessment of safety of frozen foods.

This study aimed to assess the microbiological quality of 90 frozen food samples (50 samples of raw frozen vegetables including molokeya, okra, green peas, peas + carrot, and artichoke, 20 of frozen poultry products and 20 of frozen meat products), and to assess the level of women practice during handling. A cross-sectional study was conducted. Results showed that the mean aerobic mesophilic plate count of frozen vegetables was 3.4 x 10(5) +/- 7.3 x 10(5) cfu/g. The mean mold and yeast count was 3.9 x 10(3) +/- 1.1 x 10(4) cfu/g. The mean coliform count was 3.9 x 10 +/- 6.6 x 10 m.o./g. In case of meat product, the mean aerobic count was 2.3 x 10(5) +/- 3.2 x 10(5), that of mold and yeast was 2.5 x 10(5) +/- 8.8 x 10(5) cfu/g and that of coliform was 3.2 x 10(2) +/- 3.8 x 10(2) m.o./g. Poultry products on the other hand had a mean aerobic count of 6.8 x 10(5) +/- 1.6 x 10(6), a mean mold and yeast count of 3.5 x 10(5) +/- 7.4 x 10(5) cfu/g and a mean coliform count of 6.4 x 10(2) +/- 5.2 x 10(2) m.o./g. Fecal coliforms were detected only in 60.0% of meat product samples and in 45.0% of poultry product samples. On the other hand Staph aureus was detected only in 10.0% of poultry product samples. Difference between the 5 types of vegetables was statistically significant (P = 0.00, and 0.02, respectively) for total plate and mold and yeasts counts. Among the 113 interviewed women, 80 used frozen food products. Twenty six of them (32.5%) had scores < 50%, those were classified as being bad as they were handling frozen food improperly which would contribute to outbreaks of food borne diseases. Less than 4% of the users used satisfactory practice during handling frozen foods. Illiteracy affected significantly the level of practice.

Animals↗

PubMed1980

Occurrence of volatile nitrosamines in food: a survey of the West German market.

More than 3000 food samples from the West German market have been analysed for volatile nitrosamines. N-nitrosopyrrolidine (NPYR) and N-nitrosopiperidine (NPIP) in concentrations above 0.5 micrograms/kg were found in only 3 and 2% of the samples, respectively. N-Nitrosodimethylamine (NDMA) was detectable in 30% of the samples and 6% of them were found to contain more than 5 micrograms/kg. Consumption data given in the "Nutritional Report, 1976" allow calculation of the average daily intake of volatile nitrosamines from food. Intakes for West German males are 1.1 micrograms/day for NDMA and 0.1 micrograms/day for NPYR. With regard to NDMA, the relative contributions are 64% for beer, 10% for meat and meat products and 25% for all other foods (150 types). NDMA in beer originates in the malt, where it is formed during kilning (drying). Technological improvements to eliminate NDMA contamination of beer are reported.

Beer↗

PubMed1994

National food contamination monitoring programmes-levels of mercury, lead and cadmium in Chinese foods.

Six hundred and thirty-four food samples of six kinds were collected from Beijing, Shanghai, Jiangsu, Sichuan, Jilin and Guangdong areas, China and Hg, Pb, Cd contents were determined. The results showed that their levels in the Chinese foods were low; their levels in meat, egg, milk and fish were generally below the national hygienic standard. The average daily dietary intake of Hg, Pb, Cd were 7.25 micrograms, 103.77 micrograms and 30.72 micrograms respectively and they were all less than the ADI established by WHO.

Adult↗

PubMed2006

Investigation of several parameters influencing signal generation in flow-through membrane-based enzyme immunoassay.

Rapid-response analytical tests that can be performed at the point of sampling are based on a visual detection system. The influence of different factors on the signal generation in a membrane-based enzyme immunoassay was investigated. The research was applied to a flow-through immunoassay for the detection of ochratoxin A (OTA). This assay format is a very convenient, simple and fast qualitative screening tool. Conjugates of OTA with horseradish peroxidase (HRP) and alkaline phosphatase (AP) were used as enzyme tracers. A new conjugate OTA-AP has been synthesized in our laboratory and its performance in the assay was compared with that of OTA-HRP. Different substrate systems for HRP and AP were compared. Several reagents, including polymers and surfactants, were tested for their possible effect on signal generation with the use of OTA-HRP conjugate. Polymers such as poly(vinyl alcohol) (PVA) and poly(ethylene glycol) (PEG) 6000 exerted a favourable effect on signal amplification, whereas surfactants negatively affected assay performance. The highest signal amplification (30-70% compared to the standard assay procedure) was achieved using 0.5% PVA in tetramethylbenzidine (TMB) Colorburst substrate solution and phosphate-buffered saline (PBS) for the washing step. It allowed more reliable visual estimation of the results from OTA-HRP assay. Exclusion of the detergent (Tween 20) from the washing solution exerted a favourable effect on assay performance using both enzyme tracers. The assay using OTA-HRP was more susceptible to matrix interferences than the assay with OTA-AP. Signal development in the matrix was better for the OTA-AP assay and visual estimation of the results was easier to perform in this case. For the analysis of spiked wheat samples, OTA-AP conjugate gave a more sensitive, stable and reproducible assay with a cut-off level of 4 microg kg(-1) for OTA. The application of the new OTA-AP conjugate resulted in improved assay performance for the food samples.

Alkaline Phosphatase↗

PubMed2000

Choice biases in delayed matching-to-sample duration with pigeons: Manipulations of ITI and delay illumination.

Two experiments investigated the effects of similarity between intertrial interval (ITI) and delay illumation on the choose-short effect. Different groups of pigeons learned to match "short" (2 s) and "long" (6 or 8 s) food samples to green and red test stimuli in a matching-to-sample procedure with a 5-s training delay. Subsequent 10- and 20-s delay tests revealed choose-short effects if the ITI and delay were both illuminated (i.e., group ON-ON), if the ITI and delay were both dark (i.e., group OFF-OFF), and if the ITI was illuminated and the delay was dark (i.e., group ON-OFF). In addition, either a choose-short effect or a choose-long effect was observed if the ITI was dark and the delay was illuminated (i.e., group OFF-ON). Results are incompatible with the confusion/instructional failure view of the choose-short effect.

Animals↗

PubMed2005

Determination of biogenic amines by capillary zone electrophoresis with conductometric detection.

A capillary zone electrophoresis (CZE) method with conductometric detection of biogenic amines (cadaverine, putrescine, agmatine, histamine, tryptamine and tyramine) is described. The optimised background electrolyte was the following: 15 mM histidine + 5 mM adipic acid + 1.5 mM sulphuric acid + 0.1 mM ethylenediaminotetraacetic acid + 0.1% hydroxyethylcellulose + 50% methanol. A clear separation of six biogenic amines from other components of acidic sample extract was achieved within 10 min. Method characteristics, i.e., linearity (0-100 micromol/ml), accuracy (recovery 86-107%), intra-assay repeatability (2-4%), and detection limit (2-5 micromol/l) were evaluated. Low laboriousness, sufficient sensitivity, speed of analysis, and low running cost are important attributes of this method. The developed method was successfully applied on the determination of biogenic amines in selected food samples.

Beer↗

PubMedDate not supplied

Purge and trap method for determination of ethylene dibromide in table-ready foods.

An improved method has been developed for the determination of ethylene dibromide (EDB, 1,2-dibromoethane) in a variety of table-ready foods. Samples are mixed with water and sparged with nitrogen for 1 h with stirring in a water bath at 100 degrees C. The EDB collected on the adsorbent Tenax TA is eluted with hexane and determined by gas chromatography (GC) with electron capture (EC) and confirmed with Hall electrolytic conductivity (HECD) detection using a second GC column. The highest levels of EDB were also confirmed by full scan GC/mass spectrometry (GC/MS). Twenty-five table-ready foods from the Food and Drug Administration's Total Diet Study that were analyzed by this method exhibited levels up to 70 ppb (pecans). Recoveries from fortified samples ranged from 91 to 104%. Values from this procedure were compared to those obtained by a modified Rains and Holder codistillation method. In all 25 samples this purge and trap procedure showed equivalent or superior recoveries and detected levels of EDB.

Chromatography, Gas↗

PubMed2005

Development of green fluorescent protein-expressing bacterial strains and evaluation for potential use as positive controls in sample analyses.

Strains of enterohemorrhagic Escherichia coli O157:H7 and Salmonella Typhimurium were engineered to express the gene for a modified green fluorescent protein (GFP) and were evaluated for potential use as positive controls in sample analyses. The strains fluoresced when observed as colonies with a handheld UV lamp or as individual cells under a fluorescent microscope. The strains maintained their fluorescence following growth in three series of transfer experiments including 8 to 11 passages from broth to broth and twice for 15 consecutive transfers from broth onto Trypticase soy agar plates. Cultures also maintained stability in the ability to fluoresce when agar plates were refrigerated (4 degrees C) for up to 12 days. Growth characteristics of the GFP-positive strains were comparable to those of corresponding control strains. The GFP-positive strains were successfully identified using rapid diagnostic methods and were differentiated from their corresponding non-GFP strains by pulsed-field gel electrophoresis but not by repetitive extragenic palindromic PCR. The GFP-positive and the control strains were recovered successfully from individually inoculated food samples (Feta cheese, raw shrimp, cooked shrimp, and cooked crawfish). However, in one Feta cheese sample and one raw shrimp sample inoculated with combined GFP-positive and GFP-negative cultures, colonies of the GFP-positive strains were not observed under UV light; fluorescing cells in one of the inoculated samples (raw shrimp) were revealed by microscopy. In general, the isolates from the inoculated foods were GFP positive by microscopic examination; the pure isolates could also be restreaked onto Trypticase soy agar, and colonies could be visually examined under UV light. Because GFP strains are not known to occur naturally in the environment, the use of the Salmonella GFP-positive strain may offer advantages as a positive control even when distinct and rare serotypes are available. The GFP-positive E. coli O157:H7 strain may also prove beneficial for use as a positive control strain for sample analyses.

Animals↗

PubMed2006

Radionuclide concentrations in the diet of residents in a high level natural radiation area in Iran.

Concentrations of 137Cs and 226Ra in the diet (foodstuffs and drinking water) of adult inhabitants in the high-level natural radiation area (HLNRA) of Ramsar, Iran have been determined. The annual intake of foodstuffs was estimated on the basis of their average annual consumption. Food samples collected from local markets were analyzed by means of a gamma spectrometer. The estimated annual dietary intakes of 137Cs and 226Ra were 130Bq and 245Bq, respectively. The concentrations of natural radionuclides in food and drinking water of the residents are higher than the world average, and are correlated with the high concentration of these radionuclides in soil and water. Calculations were also made to determine the potential dose to an individual consuming such diets.

Cesium Radioisotopes↗

PubMed1992

Chromatographic methods for the analysis of heterocyclic amine food mutagens/carcinogens.

A series of potent heterocyclic amines that are mutagenic and carcinogenic have been discovered that are formed in some heated foods, most notably, meats derived from muscle. Determining the heterocyclic amine content in foods and food products is required for toxicological research, industry quality control, and possibly in the future, regulatory control. The contents of food needs to be determined using reliable analytical techniques. Since heterocyclic amines are present in foods at ng/g levels, a variety of liquid-liquid or solid-phase purification techniques are required, followed by gas or high-performance liquid chromatography. Peak detection has been successful using UV, fluorescence, and mass spectrometric detection, and biological activity using the Ames/Salmonella test. The low levels present require that chromatographic efficiency, and both detector sensitivity and selectivity be optimized. The cartridge solid-phase extraction and high-performance liquid chromatography method have been used to measure the known food-derived heterocyclic amines for several types of food, and to the authors knowledge, this is the only method undergoing intralaboratory comparison and validation. Our analysis of the literature shows that chromatographic analysis of the heterocyclic amines by high-performance liquid chromatography or gas chromatography (with derivatization) is satisfactory for heterocyclic amine analysis in foods although the methods are just now being optimized for routine use. The biggest improvements in speed and accuracy will probably come from improved extraction methods as analysis of complex food samples for heterocyclic amines will always be a challenge.

Amines↗

PubMed2003

Application of a novel immunomagnetic separation-bacteriophage assay for the detection of Salmonella enteritidis and Escherichia coli O157:H7 in food.

Salmonella infection is the second most prevalent cause of foodborne illness in most developing countries. Meat, poultry, and dairy products are frequently implicated in outbreaks. The objective of this study was to apply a novel immunomagnetic separation (IMS)-bacteriophage assay to the detection of Salmonella enteritidis in artificially inoculated skimmed milk powder, chicken rinses, and ground beef. In all food types tested, the IMS-bacteriophage assay was able to detect an average of 3 CFU of S. enteritidis in 25 g or ml of food sample. Total assay time including pre-enrichment is about 20 h. The results indicate that the IMS-bacteriophage assay is a rapid and sensitive means of detecting S. enteritidis in these foods. The assay was successfully adapted to the detection of Escherichia coli O157:H7 and was able to detect E. coli in ground beef at the lowest inoculation level tested, 2 CFU/g. The assay was also adapted to the simultaneous detection of S. enteritidis and E. coli. The results indicate that the IMS-bacteriophage assay shows promise for the simultaneous detection of these pathogens, but further development work would be necessary to improve sensitivity and produce reliable results at low inoculation levels.

Animals↗

PubMed1997

Hydroxyapatite adherence as a means to concentrate bacteria.

Adherence to hydroxyapatite (HA) was examined as a method to concentrate bacteria from foods. Using HA at a level of 10% and suspensions of an Escherichia coli strain containing 10(9), 10(6), and 10(3) cells per ml, kinetic studies revealed that maximum adherence was attained within 5 min for all cell concentrations and that comparable log reductions (1.0 to 1.5) of cells in suspension were seen regardless of initial cell concentration. Eleven species of spoilage and pathogenic bacteria were found to adhere to HA, with seven species adhering at proportions of greater than 95%. Fluorescent viability staining revealed that cells bound to HA remained viable. There was greater than 92% adherence of indigenous bacteria to HA from three of five 1:10 dilutions of ground beef, indicating promise for the use of HA for concentrating bacteria from meat and other food samples.

Animals↗

PubMed2002

[Aflatoxins and ochratoxin A in food and risks to human health].

OBJECTIVES: The presence of mycotoxins in food has been associated with several human diseases, and health authorities have taken actions to decrease the ingestion of these compounds in the diet. A study was carried out to assess aflatoxins and ochratoxin A concentrations found in food, and to evaluate the potential risk to human health resulting from mycotoxin exposure. METHODS: Between July 1998 to December 2001, 366 food samples were analyzed, including peanuts and its products, nuts, maize, oat and/or wheat products, rice and beans. Samples were processed and the extracted mycotoxins were detected and separated using thin layer chromatography, and then quantified with fluorescence. RESULTS: Aflatoxins were detected in 19.6% of the samples: raw peanuts and its products, pop corn, maize and Brazilian nuts (>2mg/kg). Peanuts and its products showed the highest levels of aflatoxin contamination (34.7%) with up to 1280 mg/kg of AFB1+AFG1 and 1706 mg/kg of total aflatoxins. Of the positive samples, AFB1 was detected in 98.5%, AFB2 in 93%, AFG1 in 66.7%, and AFG2 in 65.4%. Ochratoxin A was not detected (<25 mg/kg) in any sample analyzed. CONCLUSION: It was found that contamination levels mainly seen in peanuts and its products exceed Brazilian regulated standards, and they can be a potential risk to regular consumers of these products. Food producers' awareness allied to monitoring programs is essential to reduce human exposure to these compounds and prevent ensuing chronic diseases.

Aflatoxins↗

PubMed2003

[Studies on the polyclonal antibody and the double-antibody enzyme-linked immunosorbent assay against E. coli O157 in food].

The polyclonal antibody (PcAb) for E. coli O157:H7 was available by intravenous injection with New Zealand rabbit with E. coli O157:H7 ATCC43895 strain. Together with the monoclonal antibody (McAb) 3A5 specific against E. coli O157 and O113:H21, a double-antibody sandwich enzyme-linked immunosorbent assay (ELISA) was developed with the as the capture antibody and the McAb 3A5 as the detection antibody. The detection limits are 10(3)-10(4) cfu/ml in pure culture of E. coli O157 and without any cross reaction with the non-O157 strains. With 10 h enrichment procedure, E. coli O157:H7 recovered well from inoculated ground poultry meat and pasteurized milk at levels of 0.1 cfu/g(cfu/ml). The results demonstrated that the double-antibody sandwich ELISA is a sensitive and specific method for detecting E. coli O157 in food samples.

Animals↗

PubMedDate not supplied

Jimson weed food poisoning. An epidemic at Usangi rural government hospital.

Ten agitated and psychotic patients were admitted to Usangi hospital after having eaten stiff-porridge (Ugali) made from millet (Serena). This had been bought from the local regional branch of the National Milling Corporation (NMC). The patients had cardinal signs of atropine poisoning, viz., psychosis with hallucinations, tachycardia, fixed dilated pupils and a dry mouth. Toxicological analysis of the food samples revealed contamination with Jimson weed (Datura stramonium) seeds which contained an atropine-like alkaloid. On studying the records of the chief government chemist, it was found that a similar type of food poisoning had occurred in at least eight other regions. The clinical picture and management of this entirely preventable type of agricultural food poisoning are discussed.

Adult↗

PubMedDate not supplied

Determining multifumigants in whole grains and legumes, milled and low-fat grain products, spices, citrus fruit, and beverages.

Whole grain and legumes, milled and low-fat products, spices, citrus fruit, and dry beverage ingredients are leached with purified, acidified acetone-water solutions. Portions of these leachates are then back-extracted with purified isooctane. Liquid beverages are directly extracted with the isooctane. Six to 10 microL of each isooctane extract is then screened for 11 fumigant residues by gas chromatography (GC) using electron-capture and Hall electroconductivity detectors, and dual 20% OV-101 columns. Further confirmation of residue identity is done on 20% OV-225/20% OV-17 (2.5 + 1 mixed-bed) and 10% SP-1000 columns. The analytes determined include methyl bromide, methylene chloride, carbon disulfide, chloroform, ethylene dichloride, methyl chloroform, carbon tetrachloride, trichloroethylene, chloropicrin, ethylene dibromide, and tetrachloroethylene, using mixed-component reference solutions. Average recoveries from fortified grain range from 25 to 85%; methyl bromide and chloropicrin were recovered the least. Recoveries from the other kinds of food samples range from 43 to 111%. Advantages of this procedure are (1) clean sample extracts, (2) ppb detection limits, (3) residue stability, (4) relative speed, quality control, and safety of the analysis, and (5) results which gave an accurate picture of residual fumigants in grain and food products.

Beverages↗

PubMed2003

Characterization of a polymerase chain reaction-based approach for the simultaneous detection of multiple animal-derived materials in animal feed.

In this study, a polymerase chain reaction (PCR) primer set capable of amplifying a mitochondrial DNA segment of multiple species (cattle, sheep, goats, deer, and elk) whose rendered remains are prohibited from being fed to ruminants was characterized. However, the primer set also amplifies DNA derived from the rendered remains of pigs and horses, which are exempt from the feed ban. PCR amplicons derived from pig DNA have a restriction endonuclease site recognized by Hinf1, while the horse DNA-derived amplicon has a unique restriction endonuclease site recognized by HypCH4III. This "universal" PCR primer produced an amplicon with DNA extracted from dairy feed containing either bovine meat and bone meal or pig blood meal. Enzymatic digestion of the PCR amplicons from these feed samples with Hinf1 resulted in cleavage products only from samples containing pig blood meal. However, Hinf1 digestion of these amplicons was not complete. Further analysis of the pig blood meal with primers specific for bovine or porcine DNA demonstrated the presence of both bovine- and porcine-derived DNA. Enzymatic digestion confirmed these findings. Additional testing was conducted with dry dog food samples labeled as containing either lamb, chicken, turkey, or chicken and fish. The universal PCR primer produced an amplicon only for the dog food containing lamb meal. This paper is the first to describe a simplified approach for the detection of the prohibited species of concern in the feed ban.

Animal Feed↗

PubMed2003

Determination of polydimethylsiloxanes by 1H-NMR in wine and edible oils.

Fourier transform (1)H-nuclear magnetic resonance (NMR) spectroscopy was suitable for the quantitative determination of polydimethylsiloxanes (PDMS) in wine and edible oil samples. This approach offers highly specific qualitative and quantitative analysis due to silicone-specific location of proton signals linked to carbon atoms located directly next to silicon atoms (0-0.5 ppm), as well as a different location of signals in the range for different organosilicon structures. The method can be used for the control of PDMS at regulatory limits in foodstuffs (10 mg kg(-1)) using hexamethyldisiloxane (HDMS) as an internal standard. Samples were prepared by extraction under suitable conditions to separate the analyte, and with analyte enrichment before (1)H-NMR analysis. Analytical procedures were developed to permit the determination of PDMS at 0.06 mg kg(-1) in wine and at 6 mg kg(-1) in edible oils samples using readily available NMR instrumentation. It was, however, possible to lower the limit of detection to 6 microg kg(-1) for wine and to 60 microg kg(-1) for edible oils using a higher field instrument (500 MHz). Relative standard deviations (S(r)) were obtained for wine (0.028) and for oil samples (0.043), which when compared with values obtained for samples spiked with PDMS (0.021) indicated that the sample preparation was the main factor determining the precision of the method. The average recovery rates for PDMS were 97 and 95% for wine and edible oils, respectively. PDMS was detected in four brands of Italian wine, with Chianti-Rafaello containing the highest concentration (0.35 mg kg(-1)), and in four types of edible oils, highest concentration (11.9 mg kg(-1)) being found in Italian corn oil. None of the levels of PDMS found in the food samples exceeded the permissible standards laid down by the Codex Alimentarius Commission (10 mg kg(-1)), with the exception of the one corn oil sample.

Dimethylpolysiloxanes↗