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PubMedDate not supplied

Infectivity with human ascariasis in Ibadan Oyo State, Nigeria.

Some of the common foodstuffs that assist in the transmission of ascariasis in Ibadan have been determined. The frequency of recovery of Ascaris ova in the different food samples examined varied from 9.6% in tomatoes to 25.6% in lettuce leaves. The indiscriminate pollution of Ibadan environment with human faeces enables the foodstuff consumed raw to serve as effective sources of heavy Ascaris infection which lead to other medical complications. The strategies for the control of Ascaris infection in Ibadan were discussed.

Ascariasis↗

PubMed2002

Iodine content of traditional Greenlandic food items and tap water in East and West Greenland.

OBJECTIVES: The iodine intake level is important for the occurrence of thyroid disorders in a population. The iodine intake in Greenland has been proposed to be more than ten times the recommended level. However, no measurements have been performed to determine the iodine content of Greenlandic food items, drinking water, and beverages available in East and West Greenland. STUDY DESIGN: Food samples were collected at the local market, kalaalimineerniarfik, in Nuuk and Ammassalik, and tap water was obtained from all towns in Greenland. Beverages were purchased at Kalaallit Niuerfiat KNI Pisiniarfik. RESULTS: Iodine content of seal, whale, wild fowl, reindeer, and musk ox varied between 4 and 195 microg/kg with low values for terrestrial animals (< 10 microg/kg) and higher values for marine animals (10-195 microg/kg). The iodine content of fish varied from 9 microg/kg in freshwater fish to 1,380 microg/kg in a sample of cod. The iodine content of sea mammals was: blubber 130 microg/kg; viscera 70 microg/kg; meat 21 microg/kg. No difference was observed between animals from East Greenland and West Greenland (P > 0.1). Iodine content of tap water was below 3.3 microg/l for all towns. Two sorts of beer had a high iodine content, up to 240 microg/l. The iodine content of all other beverages was 5-38 microg/l. CONCLUSIONS: We found a relatively high iodine content in marine animals but low iodine content in tap water and beverages in Greenland. The food and drinking water evaluated in the present study indicate adequate iodine intake in this area and do not support the notion that Greenland is an area of excessive iodine intake.

Animals↗

PubMed1980

[Analytical determination of polysaccharide thickening agents for foods--a review (author's transl)].

In this report, the analytical methodology, as developed by the authors for polysaccharides, used as thickening agents in foods is reviewed and summerized. Present additive regulations increase actuality and need for this subject. The analytical methodology consists of the following steps: a) isolation of the polysaccharides from the food samples, b) purification of the polysaccharide, c) determination of the monomeric compounds by thin layer chromatography or by gas chromatography, d) separation into neutral and into acid compounds by ion exchange chromatography on DEAE-Cellulose and e) determination of the types of linkages between monomeric compounds by permethylation.

Chromatography, DEAE-Cellulose↗

PubMedDate not supplied

Evaluation of staphylococcal food contamination in four different culture media.

The efficiency of Baird-Parker agar, mannitol-salt agar, Vogel-Johnson agar and Giolitti-Cantoni broth for the detection of Staphylococcus aureus from food samples, was studied by comparing the numbers of Staphylococcus recovered from the samples, the degree of selectivity reached and the recovery of coagulase and thermonuclease positive staphylococci. Lowest counts of Staphylococcus were obtained with Giolitti-Cantoni broth. The mannitol-salt agar proved to be the most efficient media system with respect to the number of staphylococci recovered and the degree of selectivity reached. None of these media was highly selective for the isolation and detection of S. aureus; therefore, it is necessary to identify the isolated colonies in all cited media, in order to use rightly the current guidelines for microbiological quality of foods.

Animals↗

PubMed2003

Multi-residue screening of pesticides in vegetables, fruits and baby food by stir bar sorptive extraction-thermal desorption-capillary gas chromatography-mass spectrometry.

The performance of stir bar sorptive extraction (SBSE) for the enrichment of pesticides from vegetables, fruits and baby food samples is discussed. After extraction with methanol, an aliquot is diluted with water and SBSE is performed for 60 min. By applying a new thermal desorption unit (TDU), fully automated and unattended desorption of 98 stir bars is feasible, making SBSE very cost-effective. The presence of pesticide residues is elucidated with the retention time locked gas chromatography-mass spectroscopy method (RTL-capillary GC-MS). With SBSE-RTL-capillary GC-MS operated in the scan mode, more than 300 pesticides can be monitored in vegetables, fruits and baby food. The multi-residue method (MRM) described provides detectabilities from the mg/kg (ppm) to the sub-microg/kg (ppb) level, thereby complying with the maximum residue levels (MRLs) set by regulatory organizations for pesticides in different matrices. Several examples, i.e. pesticide residues in lettuce, pears, grapes and baby food, illustrate the potential of SBSB-RTL-capillary GC-MS.

Fruit↗

PubMed1994

Magnetic separation techniques in diagnostic microbiology.

The principles of magnetic separation aided by antibodies or other specific binding molecules have been used for isolation of specific viable whole organisms, antigens, or nucleic acids. Whereas growth on selective media may be helpful in isolation of a certain bacterial species, immunomagnetic separation (IMS) technology can isolate strains possessing specific and characteristic surface antigens. Further separation, cultivation, and identification of the isolate can be performed by traditional biochemical, immunologic, or molecular methods. PCR can be used for amplification and identification of genes of diagnostic importance for a target organism. The combination of IMS and PCR reduces the assay time to several hours while increasing both specificity and sensitivity. Use of streptavidin-coated magnetic beads for separation of amplified DNA fragments, containing both biotin and a signal molecule, has allowed for the conversion of the traditional PCR into an easy-to-read microtiter plate format. The bead-bound PCR amplicons can also easily be sequenced in an automated DNA sequencer. The latter technique makes it possible to obtain sequence data of 300 to 600 bases from 20 to 30 strains, starting with clinical samples, within 12 to 24 h. Sequence data can be used for both diagnostic and epidemiologic purposes. IMS has been demonstrated to be a useful method in diagnostic microbiology. Most recent publications describe IMS as a method for enhancing the specificity and sensitivity of other detection systems, such as PCR, and providing considerable savings in time compared with traditional diagnostic systems. The relevance to clinical diagnosis has, however, not yet been fully established for all of these new test principles. In the case of PCR, for example, the presence of specific DNA in a food sample does not demonstrate the presence of a live organism capable of inducing a disease. However, all tests offering increased sensitivity and specificity of detection, combined with reduced time of analysis, have to be seriously evaluated.

Animals↗

PubMed1996

[Iodine deficiency in the Carpathian endemic region and iodine prophylaxis in Southern Poland].

The improvement of the health status of the population of Southern Poland resulted in great extend from the introduction of table salt iodination in 1935. This prophylaxis caused a decrease of serious iodine deficiency disorders. Twice was the salt fortification process interrupted (1939-1945 and 1980-1986); and this brought the increase of goiter incidence in the population. Laboratory examinations of water and food samples coming from goiter endemic area of Southern Poland presented a low iodine level. The unsatisfactory clinical results of the iodine prophylaxis and the unstable concentration of KI in salt, force to correct the previous action. Apart of the epidemiological studies to be performed in order to establish the optimal dose of KI in table salt, the improvement of the iodination technique and subsequent laboratory control of KI concentration in salt-is urgently needed. The fortification process should be not only restricted to table salt, but also the industrial salt used in the food production ought to be iodinated. Nutrition education should be strengthen to convince the population to use iodized salt in household food production.

Adolescent↗

PubMed2000

Determination of the plant growth regulator chlormequat in food by liquid chromatography-electrospray ionisation tandem mass spectrometry.

A confirmatory method for the determination of trace levels of chlormequat in a variety of different food matrices was developed. It entails a single clean-up step over a solid-phase cation exchange resin and subsequent liquid chromatography-electrospray ionisation tandem mass spectrometry using a stable isotopically labelled internal standard. Mass spectral acquisition was done in selected reaction monitoring mode, selecting the transitions from both the 35Cl and the 37Cl isotope of chlormequat. Recoveries after extraction and clean-up, determined with radio-labelled chlormequat and averaged over the spiking range (16-65 microg kg(-1)) in four different commodities, were within 88-96%, with a coefficient of variation better than 8%. The method can be applied to pears, pear juice concentrates, fruit purées, and cereal products, with typical limits of detection for chlormequat estimated at 2-5 microg kg(-1). A survey of different food commodities revealed that chlormequat was detectable--albeit at very low levels--in many of the food samples analysed, with the highest concentration recorded in pears purchased in Switzerland and of South African origin (5.5 mg kg(-1)). Measurements were also conducted on two LC-MS instruments and demonstrate the versatility and robustness of the method and its applicability to instruments of different ion source design.

Calibration↗

PubMed2002

Detection of Salmonella in foods using Tecra Salmonella VIA and Tecra Salmonella UNIQUE rapid immunoassays and a cultural procedure.

The presence of Salmonella in 200 raw food samples of animal origin was investigated by means of the rapid immunoassays Tecra Salmonella VIA and Tecra Salmonella UNIQUE (Tecra Diagnostics, Rosewille, New South Wales, Australia) and a cultural procedure. Forty-five samples (22.5%) were Salmonella positive by at least one of the three methods. The number of positive samples according to the analytical method was 34 (75.6%) for the cultural procedure, 29 (64.4%) for Tecra Salmonella VIA, and 27 (60.0%) for Tecra Salmonella UNIQUE. Tecra Salmonella UNIQUE detected three positive samples that were not detected by the two other methods. The cultural method also detected three positive samples that both rapid methods were unable to detect. McNemar's chi-square tests indicated that the differences between results given by the rapid immunoassays when compared with those of the cultural method were not significant (P > 0.05).

Bacteriological Techniques↗

PubMedDate not supplied

Simplified method for determination of total dietary fiber in foods.

A simplified method, based on the same principles as the AOAC enzymatic-gravimetric method for determining total dietary fiber (TDF) (43.A14-43.A20), has been tested on 12 food samples which had been used in other collaborative studies. TDF values obtained in our laboratory for these 2 methods were in good agreement (y = 0.96x + 0.39; r = 0.999). The simplified method uses a single incubation period and only 1 enzyme (amyloglucosidase), and thus yields smaller blank and ash corrections but a higher protein correction.

Dietary Fiber↗

PubMed2005

Detection of Listeria monocytogenes and the toxin listeriolysin O in food.

Listeria monocytogenes is an emerging bacterial foodborne pathogen responsible for listeriosis, an illness characterized by meningitis, encephalitis, and septicaemia. Less commonly, infection can result in cutaneous lesions and flu-like symptoms. In pregnant women, the pathogen can cause bacteraemia, and stillbirth or premature birth of the fetus. The mortality rate for those contracting listeriosis is approximately 20%. Currently, the United States has a zero tolerance policy regarding the presence of L. monocytogenes in food, while Canada allows only 100 cfu/g of food. As such, it is essential to be able to detect the pathogen in low numbers in food samples. One of the best ways to detect and confirm the pathogen is through the detection of one of the virulence factors, listeriolysin O (LLO) produced by the microorganism. The LLO-encoding gene (hlyA) is present only in virulent strains of the species and is required for virulence. LLO is a secreted protein toxin that can be detected easily with the use of blood agar or haemolysis assays and it is well characterized and understood. This paper focuses on some of the common methods used to detect the pathogen and the LLO toxin in food products and comments on some of the potential uses and drawbacks for the food industry.

Agar↗

PubMed1996

Pesticide residue analysis in foodstuffs applying capillary gas chromatography with atomic emission detection state-of-the-art use of modified multimethod S19 of the Deutsche forschungsgemeinschaft and automated large-volume injection with programmed-temperature vaporization and solvent venting.

Atomic emission detection (AED) provides high element-specific detection of all compounds amenable to gas chromatography (GC). The heteroatoms nitrogen, chlorine, phosphorus, sulfur, bromine and fluorine, which are important elements in pesticide residue analysis, are of major interest. A main drawback of AED is its lower sensitivity with respect to other selective detection methods used in pesticide residue analysis such as electron-capture and nitrogen-phosphorus detection. This holds true especially for the important nitrogen trace. For this reason, more sensitive detection can be achieved by injection of larger volumes or higher concentrations of sample extracts, because matrix compounds were usually registered only in the carbon, hydrogen and oxygen traces. This paper focuses on recent developments from the authors' laboratory in order to demonstrate the feasibility of screening analyses with the identification of pesticide residues down to the 0.01 ppm concentration level in plant foodstuffs. This has been achieved by means of automated large volume injection with programmed-temperature vaporization and solvent venting as well as careful optimization of make-up and reactant gases with AED. Clean up follows the principle of multimethod S19 of the Deutsche Forschungsgemeinschaft in a reduced procedure. After elimination of lipids and waxes by gel permeation chromatography, extracts from 10 g of the food samples were concentrated to 200 microliters, of which 12.5 microliters were introduced into the GC-AED system. Two analyses were usually performed with the element traces of sulfur, phosphorus, nitrogen and carbon in the first run and chlorine and bromine in the second run. Fluorine and oxygen were not detected in any screening analyses. The method has proved to be of great value especially with "problem foodstuffs". The limits of detection were determined for 385 pesticides and are presented together with their retention data.

Chromatography, Gas↗

PubMed1999

Automated detection of Salmonella spp. in foods.

An automated method to detect salmonellae in foods was developed and tested in food samples intentionally contaminated with the test organisms. Liquid eggs, shell eggs, dry eggs, skim milk and chicken were spiked with Salmonella enteritidis, S. typhimurium or S. newport to yield 2 to 25 CFU per 25 g or ml of sample. Following pre-enrichment in universal pre-enrichment broth at 42 degrees C for 6 h (eggs and milk) or 16 h (chicken), Salmonella cells were captured by immunomagnetic beads coated with Salmonella antibody (Vicam, Watertown, MA). The beads were transferred to selective liquid media containing carbohydrate (dulcitol or xylose), amino acid (lysine or ornithine), and H2S indicator, and incubated at 42 degrees C in the BioSys instrument (MicroSys, Ann Arbor, MI). Salmonella positive samples were identified by black discoloration of the media during incubation, while negative samples remained colorless. These color changes were recorded by the instrument. All the artificially contaminated samples tested positive within 15-18 h, while control samples remained negative during 24 h incubation. The results agreed with standard identification procedures. A total of 24 h was required to detect 2 to 25 CFU of the pathogen in 25 g or ml of eggs and milk, and up to 36 h in chicken, compared to 72 h in the standard methods.

Animals↗

PubMed2004

Extending applicability of the oxygen radical absorbance capacity (ORAC-fluorescein) assay.

The ORAC-fluorescein (ORAC-FL) method recently validated using automatic liquid handling systems has now been adapted to manual handling and using a conventional fluorescence microplate reader. As calculated for Trolox, the precision of the method was <3.0, expressed as percent coefficient of variation. The accuracy of the method was <2.3, expressed as percent variation of the mean. The detection and quantification limits were those corresponding to 0.5- and 1-microM Trolox standard solutions, respectively. The method has been applied to 10 pure compounds (benzoic and cinnamic acids and aldehydes, flavonoids, and butylated hydroxyanisole), to 30 white, rose, and bottled- and oak-aged red wines, and to 7 commercial dietary antioxidant supplements. All samples exhibited a good linear response with concentration. As seen by other methodologies, the chemical structure of a compound determines its antioxidant activity (ORAC-FL value). Of particular interest were the results with oak-aged red wines from different vintages (1989-2002) that confirm influence of vintage, but not origin of the oak, in the antioxidant activity of wines from the same variety. Dietary antioxidant supplements presented a great variability (170-fold difference) in their antioxidant potency. This work proves applicability of the ORAC-FL assay in evaluating the antioxidant activity of diverse food samples.

Antioxidants↗

PubMed1992

[Detection and identification of pathogenic bacteria by polymerase chain reaction with primers from DNA sequence of ribosomal RNA].

Applicability of the polymerase chain reaction method for identification of pathogenic bacteria was examined with the primers synthesized from the ribosomal RNA gene sequence containing both homologous and species-specific regions of bacterial species from Mycoplasma to Mycobacteria. Two out of the nine sets of promoters prepared, each covering about 650 nucleotides spanning from 16S RNA to 23S RNA regions, produced the corresponding DNA fragments from all the strains tested, and another set did so from all species but Mycoplasma. This method enabled one to detect and identify E. coli in a sample containing 2 x 10(2) CFU. The restriction enzyme patterns of the PCR products obtained with Hae-III, Hha-I, Mbo-I, Msp-I, Rsa-I and Taq-I were so characteristic as to differentiate one species from another. Ten strains of E. coli showed identical restriction patterns and 10 of S. aureus also showed identical patterns indicating that the restriction pattern is species-specific. The method may be applicable to detection and identification of a certain species bacteria which are suspected to be consealed in water or food samples, or clinical specimens, especially when the consealed bacterial genus or species can not be predicted.

Base Sequence↗

PubMed1998

Membrane filter method based on FC-5-bromo-4-chloro-3-indolyl-beta-D-glucuronide medium facilitates enumeration of Escherichia coli in foods and poultry carcass rinses.

Three enumeration methods for Escherichia coli in foods, the Health Protection Branch most-probable-number (MPN) method MFHPB-19, a hydrophobic grid membrane filter method MFHPB-26 (HGMF-indole), and a hydrophobic grid membrane filter method utilizing 5-bromo-4-chloro-3-indolyl-beta-D-glucuronide in a (modified) mFC agar (HGMF-FC-BCIG) were compared in 80 food samples that included naturally and artificially contaminated raw vegetables, mung bean and alfalfa sprouts, raw meats, and chicken carcass rinses. The number of samples confirmed as positive for E. coli were 44, 36, and 42 for the MPN, HGMF-indole, and HGMF-BCIG methods, respectively. By the MPN method, E. coli was detected in 3 samples at levels below the limits of detection of the HGMFs; but the MPN method was very time-consuming. With the HGMF-indole procedure E. coli was missed in 4 artificially contaminated samples. With the HGMF-FC-BCIG method E. coli was enumerated in 1 sample of bean sprouts missed by both the MPN and HGMF-indole procedures. High levels of indole-positive Klebsiella spp. in bean sprouts interfered with the HGMF-indole method, but the blue colonies of E. coli were easily observed in the HGMF-FC-BCIG method. Specificity of the HGMF-FC-BCIG method is high enough that routine confirmation should be unnecessary; however, confirmation of presumptive E. coli is easier since no lethal indole-staining step is involved. It appears to be a very simple method for quantifying E. coli in foods or carcass rinses.

Animals↗

PubMed1976

Survey of food products for volatile N-nitrosamines.

A variety of food products containing nitrite were analyzed for 14 volatile N-nitrosamines by using a method demonstrated to be sensitive to 10 ppb. A total of 121 food samples were screened for volatile N-nitrosamine content. N-Nitrosopyrrolidine was confirmed in fried bacon at levels up to 139 ppb. N-Dimethylnitrosamine, N-nitrosopyrrolidine, and N-nitrosopiperidine were also confirmed in spice-cure mixtures at levels ranging from 50 to 2000 ppb.

Dimethylnitrosamine↗

PubMedDate not supplied

Effect of sodium chloride and potassium chloride on growth response of yeasts Saccharomyces uvarum and Kloeckera brevis to free vitamin B6.

Acid hydrolysis is the most commonly used extraction procedure for the microbiological assay of vitamin B6 in food samples. Because NaCl or KCl is formed as a result of the extraction procedure, these 2 salts were tested as possible agents that may influence the growth response of the yeasts Saccharomyces uvarum and Kloeckera brevis. Results indicate that NaCl and KCl do effect the growth response of these 2 yeasts, depending on the salt concentration and the B6 vitamer present.

Food Microbiology↗