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PubMed2004

Rapid and specific detection of Salmonella spp. in animal feed samples by PCR after culture enrichment.

A PCR procedure has been developed for routine analysis of viable Salmonella spp. in feed samples. The objective was to develop a simple PCR-compatible enrichment procedure to enable DNA amplification without any sample pretreatment such as DNA extraction or cell lysis. PCR inhibition by 14 different feed samples and natural background flora was circumvented by the use of the DNA polymerase Tth. This DNA polymerase was found to exhibit a high level of resistance to PCR inhibitors present in these feed samples compared to DyNAzyme II, FastStart Taq, Platinum Taq, Pwo, rTth, Taq, and Tfl. The specificity of the Tth assay was confirmed by testing 101 Salmonella and 43 non-Salmonella strains isolated from feed and food samples. A sample preparation method based on culture enrichment in buffered peptone water and DNA amplification with Tth DNA polymerase was developed. The probability of detecting small numbers of salmonellae in feed, in the presence of natural background flora, was accurately determined and found to follow a logistic regression model. From this model, the probability of detecting 1 CFU per 25 g of feed in artificially contaminated soy samples was calculated and found to be 0.81. The PCR protocol was evaluated on 155 naturally contaminated feed samples and compared to an established culture-based method, NMKL-71. Eight percent of the samples were positive by PCR, compared with 3% with the conventional method. The reasons for the differences in sensitivity are discussed. Use of this method in the routine analysis of animal feed samples would improve safety in the food chain.

Animal Feed↗

PubMed2001

Determination of N-(carboxymethyl)fumonisin B(1) in corn products by liquid chromatography/electrospray ionization--mass spectrometry.

It is well-known that fumonisin B(1) (FB(1)) in corn meal decreases during baking, frying, and cooking, but it is still not exactly clear how heating affects the formation of N-(carboxymethyl)fumonisin B(1) (NCM-FB(1)), the reaction product of FB(1) and reducing sugars. In model experiments corn grits were spiked with FB(1) (2 mg/kg) and D-glucose (50 g/kg) or sucrose (50 g/kg) and manufactured into extrusion products at various temperatures (160--180 degrees C) and moisture levels (16--20%). A liquid chromatography/electrospray ionization-mass spectrometry method using isotopically labeled fumonisin FB(1)-d(6) as an internal standard was developed for the determination of NCM-FB(1). For sample cleanup solid-phase C18 cartridges were used. The detection limit achieved with this method was 10 ng/g (signal-noise ratio = 3:1) using the protonated molecule [M + H](+) signal of NCM-FB(1) (m/z 780) in the selected ion monitoring mode. Low concentrations of NCM-FB(1) (29-97 ng/g) were detected in all samples spiked with D-glucose and FB(1), whereas those spiked with FB(1) and sucrose showed only NCM-FB(1) in samples produced at 180 degrees C (NCM-FB(1) = 27 ng/g). Various corn-containing food samples from the German market were analyzed for the presence of NCM-FB(1), FB(1), and hydrolyzed fumonisin B(1) (HFB(1)). All samples were contaminated with FB(1) (22--194 ng/g) and HFB(1) (5--247 ng/g). Six of nine samples contained NCM-FB(1) in low concentrations ranging from 10 to 76 ng/g. From these data and the low toxicity of NCM-FB(1) it can be concluded that the significance of NCM-FB(1) in food seems to be a minor one.

Carbohydrates↗

PubMed1996

The polymerase chain reaction: applications for the detection of foodborne pathogens.

Faster methods for the detection of foodborne microbial pathogens are needed. The polymerase chain reaction (PCR) can amplify specific segments of DNA and is used to detect and identify bacterial genes responsible for causing diseases in humans. The major features and requirements for the PCR are described along with a number of important variations. A considerable number of PCR-based assays have been developed, but they have been applied most often to clinical and environmental samples and more rarely for the detection of foodborne microorganisms. Much of the difficulty in implementing PCR for the analysis of food samples lies in the problems encountered during the preparation of template DNAs from food matrices; a variety of approaches and considerations are examined. PCR methods developed for the detection and identification of particular bacteria, viruses, and parasites found in foods are described and discussed, and the major features of these reactions are summarized.

Base Sequence↗

PubMed2000

Migration of bisphenol-A diglycidyl ether (BADGE) and its reaction products in canned foods.

Bisphenol-A diglycidyl ether (BADGE) is used as an additive or starting agent in coatings for cans. The presence of hydrochloric acid in the organosol (PVC-based) lacquers results in formation of chlorohydroxy compounds of BADGE. These compounds, as well as BADGE itself, are potential migrants into the preserved food and are of toxicological concern. In the present investigation the presence of BADGE and the chlorohydroxy compounds (BADGE.HCl and BADGE.2HCl) in various kinds of canned foods from 30 brands have been determined by HPLC with fluorescence detection. BADGE was found in levels up to 5.1 mg/kg in the food and only in food from cans containing BADGE.HCl and BADGE.2HCl in the lacquers. BADGE was found both in fish in oil and in fish in tomato sauce, however, the highest amounts were found in the fatty foodstuffs. BADGE.HCl and BADGE.2HCl were found in concentrations up to 2.4 mg/kg and 8.3 mg/kg, respectively. Unlike BADGE, BADGE.2HCl was found in similar concentrations in fish in oil and in fish in tomato sauce. In aqueous and acidic foodstuffs BADGE readily hydrolyses into mono- and dihydrolysed products (BADGE.H2O and BADGE.2H2O). In this study BADGE.H2O was not found in any food sample, whereas BADGE.2H2O was found in levels up to 2.6 mg/kg. The Scientific Committee for Food (SCF) of the European Commission has proposed that a limit of restriction of 1 mg/kg food shall include BADGE itself and BADGE.H2O, BADGE.HCl, BADGE.2HCl and BADGE.HCL.H2O. The present results indicate that the migration of BADGE.HCl and BADGE.2HCl, compounds with almost no data on toxicity, implies a greater problem than BADGE.H2O and BADGE.2H2O.

Bisphenol A-Glycidyl Methacrylate↗

PubMed1983

The incidence of Bacillus cereus in foods in Central Thailand.

Thirty of 53 different raw and cooked or processed foods obtained in Central Thailand were demonstrated to contain Bacillus cereus. The level of contamination was found to depend on the type of food sampled; the mean was 3.2 X 10(6) organisms/gm on raw and cooked or processed foods ready for consumption, and 2.8 X 10(8) organisms/gm on cooked or processed foods kept overnight at kitchen temperature. B. cereus was commonly found on rice (both uncooked and boiled or fried), dried chilli pepper, shrimp paste, and on certain kinds of cooked foods seasoned with these products. Most of the total of 275 B. cereus isolates were found to possess biochemical reactions typical for B. cereus. Variations were also examined among several isolates. Nineteen per cent of the isolates did not produce acid from salicin. Certain types of the food tested were also demonstrated by volunteer experiments to carry enterotoxigenic B. cereus.

Bacillus cereus↗

PubMedDate not supplied

[Pesticides in the diet: adding pieces to the puzzle].

OBJECTIVES: To improve information on exposure to pesticides through diet in Spain by reporting the results on 88 pesticide parameters in 1,109 food samples obtained between 1998 and 2003 as part of the Barcelona program for research on the health quality of foods. MATERIAL AND METHOD: The results are presented by food groups. For fruits and vegetables, the results were compared with those for the previous period. Statistical comparisons were performed using the chi2 test. RESULTS: Of the 1,109 samples, 116 were positive for pesticides (10.5%). Persistent chlorinated compounds were detected in 1.5% and other compounds were found in 14.4%. Positive results were concentrated in fruits, vegetables, spices, cereals and their derivatives. There were no positive results among vegetable oils, eggs or fish products, and almost none in dairy products and meats. Fruits contained the greatest number of pesticides but none were persistent. Vegetables contained fewer pesticides, but some of these were persistent chlorinated compounds. Comparison of the results for fruits and vegetables with those of the 1989-97 period revealed no significant trends. CONCLUSIONS: Although a considerable number of samples contained pesticides, most of these were not persistent chlorinated compounds. The number of pesticides in fruits was notable.

Food Contamination↗

PubMed1983

Comparative analysis of meat samples prepared with food chopper and bowl cutter.

Analyses of meat samples after preparation with either a bowl cutter or by the official procedure with a food chopper were compared for homogeneity of comminution and for differences in fat, moisture, and protein content. Cutting time in the bowl cutter was limited to minimize temperature rise in samples. Beef chuck, pork shoulder, and beef shank, cheek, and tongue were used in the study. Variances of replicate analysis data for the 5 meat types were pooled for either cutter or chopper treatment and for each analyzed component. Sample portions cut and mixed by using the bowl cutter were more homogeneous than those ground with a food chopper. Comparative accuracy was indicated by fat and moisture means: 5 were in good agreement and 5 differed significantly; 3 of 5 paired protein means differed significantly but were within 0.3% protein. Results on precision and accuracy as well as the simplicity and convenience of the bowl cutter procedure favor its use as an alternative to a food chopper for preparing meat samples for analysis.

Animals↗

PubMed1991

Endogenous nitrosamines and liver fluke as risk factors for cholangiocarcinoma in Thailand.

Cholangiocarcinoma (CCA) is one of the most prevalent cancers in north-east Thailand and has been associated with infestation by the liver fluke Opisthorchis viverrini (OV). Two samples of 12-h overnight urine (after dosing with 500 mg proline and 200 mg ascorbic acid or 500 mg proline alone) were collected from about 100 inhabitants in five contrasting incidence areas for CCA and hepatocellular carcinoma. The incidences of CCA and hepatocellular carcinoma were not correlated with either the amount of NPRO or other nitrosamino acids, endogenous nitrosation potential (difference in NPRO levels between proline dose and proline and ascorbic acid dose), or nitrate level. However, when urinary levels of nitrosamino acids were compared in subjects living in high-risk areas, subjects who were positive for OV antibody excreted significantly more (p less than 0.01) NPRO (12.3 +/- 18.7 micrograms/12 h) after proline ingestion than those who were negative 3.5 +/- 3.2 micrograms/12 h). After ingestion of ascorbic acid, the NPRO levels in the positive subjects were significantly reduced (p less than 0.01) to 2.4 +/- 2.0 micrograms/12 h, suggesting that endogenous nitrosation of proline was inhibited. Thus, endogenous nitrosation potential estimated from the difference of NPRO and sum of nitrosamino acids excreted in the two urine samples was significantly higher in subjects positive for the OV antibody. In addition, of the representative food samples and beverages consumed frequently in high-risk areas for CCA, fermented fish and pork contained N-nitrosodimethylamine (0-26 micrograms/kg), N-nitrosopyrrolidine (0-117 micrograms/kg) and N-nitrosopiperidine (0-23 micrograms/kg).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoma, Bile Duct↗

PubMed2005

SPME-GC-pyrolysis-AFS determination of methylmercury in marine fish products by alkaline sample preparation and aqueous phase phenylation derivatization.

Characterization of a cost-efficient analytical method based on alkaline sample digestion with KOH and NaOH, followed by aqueous phase phenylation derivatization with NaBPh4 and solid phase microextraction (SPME) for the determination of methylmercury in typical fish-containing food samples commercially available in Hungary, is reported. The sample preparation procedure along with the applied SPME-GC-pyrolysis-AFS system was validated by measuring certified reference materials (CRM) BCR-464, TORT-2, and a candidate CRM BCR 710. To carry out an estimation of average Hungarian methylmercury exposures via marine fish and/or fish-containing food consumption, 16 commercially available products and 3 pooled representative seafood samples of-according to a previous European survey--the three most consumed fish species in Hungary, herring, sardines, and hake, were analyzed. Methylmercury concentrations of the analyzed samples were in the range 0.016-0.137 microg of MeHg g(-1) dry weight as Hg.

Chromatography, Gas↗

PubMedDate not supplied

Identification of potential migrants from samples of dual-ovenable plastics.

The analysis of samples of dual-ovenable cookware articles has identified chemicals with the potential to migrate into food. Samples were analysed by dynamic headspace analysis at 200 degrees C using a Tenax TA trap cooled in ice, and/or solvent extraction, followed by gas chromatography/mass spectrometry. Plastics analysed were crystalline poly(ethyleneterephthlalate) (cPET), thermoset polyester, poly(ethersulphone) and poly (4-methyl-pent-1-ene) (TPX). The greatest number and quantity of chemicals with the potential to migrate were found in thermoset polyester.

Chromatography, Gel↗

PubMedDate not supplied

Determination of total free and glucose-conjugated 3-phenoxybenzyl alcohol residues in foods by gas chromatography with electron capture detection.

A method was developed to determine the combined amounts of residual, free 3-phenoxybenzyl alcohol (permethrin alcohol) and its acetone-extractable glucosides in representative fruits and vegetables after application of pyrethyroid insecticides such as permethrin or cypermethrin. 3-Phenoxybenzyl glucoside was synthesized and used to spike food samples. Conditions were developed for extraction, enzymatic hydrolysis, derivatization with heptafluorobutyric anhydride, and cleanup prior to detection and quantitation by gas chromatography with electron capture detection. Limits of detection in various foods were < or = 0.01 ppm. In addition, 2 sets of field trial samples that were sprayed with permethrin and collected at intervals were also analyzed. In general, the amounts of total permethrin alcohol in foods were small.

Aerosols↗

PubMed2002

[Study of Salmonella contamination of restaurant meat products collected over a period of one year].

The study has been carried out on 898 food samples of animal origin: bovin meat, ovin, porcin, rabbit, turkey and chicken in 1998 from auto-control food service of Chahed laboratory. II consisted in studying and identifying salmonella serovars and to determine the nature of the most contaminated meat products. The results of the study are as follows: 3.7% of meat product samples are contaminated by salmonella. On the 480 samples of bovin meat, 4.2% are contaminated by salmonella. 3.8% ovin meat is contaminated by salmonella, 1.7% turkey meat and 3.6% chicken meat. Rabbit meat are not contaminated by salmonella. As far as the products of a bovin origin are concerned the results are as follows: -2.7% of meat is contaminated by salmonella, 5.3% of mechanically separated meat and 7.7% of giblets are also contaminated. Therefore salmonella contaminates 4.3% of red meat and 2.6% of fowl. S. anatum, Corvallis, typhimurium, Braenderup, Zanzibar, Enteritidis, Livingstone are different detected serovars. S. anatum represents 40% of contamination whereas. S. typhimurium represents 12% Of contaminations.

Data Collection↗

PubMed2002

Genetically modified maize and soybean on the Egyptian food market.

The results of a survey study on food samples produced from genetically modified soybean and maize collected from the Egyptian market are presented. Forty samples of soybean and 40 samples of maize products have been gathered randomly from markets in Cairo and Giza. The genetic modification was detected by polymerase chain reaction (PCR) using official detection methods according to section 35 of the German Foodstuffs Act. Samples were investigated for the presence of material derived from the following genetically modified organisms (GMOs) all of which are approved for food use in Europe: Roundup Ready soybean (RRS) and maize lines Bt176, Bt11, T25 and MON810. In addition, samples were examined in qualitative and quantitative analysis for the presence of material derived from the transgenic maize line StarLink (Aventis) which was approved for animal feed use exclusively in the US. Twenty % of 40 investigated soy samples contained Roundup Ready soybean; 15% of 40 maize samples tested positive for Bt176 and 12.5% positive for Bt11 maize. Furthermore, the presence of StarLink maize could clearly be demonstrated in four samples mixed with Bt176 and Bt11. The percentage of StarLink was less than 1% in quantitative analysis. The maize lines T25 and MON810 were not detected.

DNA, Plant↗

PubMed1991

Occurrence of Yersinia spp. in foods in Brazil.

Over the past 9 years, 468 bacterial strains isolated from raw and pasteurized milk, beef and pork, bovine and chicken liver, chicken heart, gizzards and lung sausage, hamburger, cheese and lettuce in different regions of the State of São Paulo and in the city of Rio de Janeiro were received by the Reference Laboratory for Yersinia in Brazil. All were confirmed to be Yersinia spp. The 468 Yersinia isolates were grouped as 184 strains because some of the bacteria isolated from the same food sample belonged to the same species, and were considered to be a single strain. The Yersinia food strains were classified as Y. enterocolitica (46), Y. intermedia (67), Y. frederiksenii (20), Y. kristensenii (8) and 43 of them were biochemically atypical. Pathogenic types were not detected.

Bacterial Typing Techniques↗

PubMed2000

Correlations between functional and occlusal tooth-surface areas and food texture during natural chewing sequences in humans.

The dental-arch surfaces preferentially used in mastication were studied by measuring functional and occlusal surface areas and comparing these to the number of chews required to swallow foods of different texture properties. The functional surface of the teeth was defined as the total area of visible wear facets on post-incisal teeth, adding to it the contacting areas of restored teeth where no facets were visible. Occlusal surface area was taken as the total area of the occluding parts of post-incisal teeth. Both surfaces were measured with computer image processing on dental-stone casts of the teeth of 31 young adults. Functional surface areas (mean 168 mm(2), four quadrants) were positively correlated with occlusal surface areas (mean 739 mm(2), four quadrants). The left:right area ratios were more variable for functional than for occlusal surfaces. Functional surface-area ratios markedly different from 1.0 might reflect functional side-preponderance of masticatory activity. Correlations between tooth surface area and the number of cycles were examined with five different food samples of known texture during side-imposed mastication. Depending on the elastic moduli of the foods, significant negative correlations were found between the left:right ratios of functional or occlusal surface areas and the left:right ratios of cycle numbers. The rheological properties of the food particles chewed were assumed to be the key factor in the correlations with either the functional or anatomical occlusal surfaces.

Adult↗

PubMed1997

Determination of ascorbic acid in foodstuffs by microdialysis sampling and liquid chromatography with electrochemical detection.

A method for the determination of ascorbic acid in foodstuffs utilising microdialysis sampling coupled with LC with electrochemical detection is described. The application of the method to liquid food samples such as milk, yoghurt and fruit juices was evaluated. Compared with the classical method, the proposed procedure features straightforward sample preparation and improved sensitivity and selectivity. A sampling rate of 20 h-1 is possible, depending on the particular sample under study.

Animals↗

PubMed2002

Absorption and metabolism of anthocyanins in elderly women after consumption of elderberry or blueberry.

The absorption and metabolism of anthocyanins (ACN) in humans was studied in four elderly women given 12 g elderberry extract (EBX) (720 mg total ACN), and six elderly women given 189 g lowbush blueberry (BB) (690 mg total ACN). The two major ACN in EBX, cyanidin-3-glucoside and cyanidin-3-sambubioside, as well as four metabolites: 1) peonidin 3-glucoside, 2) peonidin 3-sambubioside, 3) peonidin monoglucuronide, and 4) cyanidin-3-glucoside monoglucuronide were identified in urine within 4 h of consumption using HPLC-MS/MS with diode-array detector detection and retention time. Total EBX ACN excretion was 554 +/- 90 microg (mean +/- SD, n = 4) (0.077% of intake/4 h, wt/wt). In 5 of 6 women fed BB, urine samples contained ACN, which were identified as the original forms based upon comparisons to the BB food sample, which contained 24 ACN, 22 of which were identified by HPLC-MS/MS. Reasonable correlations between BB and urine proportions of the different ACN were obtained except for ACN arabinosides. Total urinary excretion during the first 6 h was 23.2 +/- 10.9 microg (mean +/- SD, n = 5) (0.004% of intake/6 h, wt/wt). Plasma ACN levels were below detection limits using 2 mL plasma in women that consumed BB. This study demonstrates for the first time that in vivo methylation of cyanidin to peonidin and glucuronide conjugate formation occurs after people consume ACN and demonstrates the low absorption and excretion of ACN compared with other flavonoids.

Absorption↗

PubMed2003

Polycyclic aromatic hydrocarbons in foods: human exposure through the diet in Catalonia, Spain.

The dietary intake of 16 polycyclic aromatic hydrocarbons (PAHs) (naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, benz[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenz[a,h]anthracene, benzo[g,h,i]perylene, and indeno[1,2,3-c,d]pyrene) by the general population of Catalonia, Spain, was calculated. Concentrations of PAHs in food samples randomly acquired in seven cities of Catalonia from June to August 2000 were measured. Eleven food groups were included in the study. High-performance liquid chromatography was used to analyze PAHs. The dietary intakes of total and carcinogenic PAHs was calculated for five population groups: children, adolescents, male adults, female adults, and seniors. Among the analyzed PAHs, there was a predominance of phenanthrene (16.7 microg/kg) and pyrene (10.7 microg/kg). By food group, the highest levels of total PAHs were detected in cereals (14.5 microg/kg) and in meat and meat products (13.4 microg/kg). The mean estimated dietary intake of the sum of the 16 PAHs was as follows: male adults, 8.4 microg/day; adolescents, 8.2 microg/day; children, 7.4 microg/day; seniors, 6.3 microg/day; female adults, 6.3 microg/day. The calculated daily intake of PAHs would be associated with a 5/106 increase in the risk for the development of cancer in a male adult with a body weight of 70 kg.

Adolescent↗