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PubMed1995

[Health survey of nitrate load in preschool institutions].

Consumption of nitrates with plant food, milk and water was studied in pre-schoolchildren aged 4-6 years going to pre-school institutions. Contents of nitrates were higher than maximum permissible level in 25.3% of food samples. It was shown that most significant consumption of nitrates was at the expense of cabbage (1.9-2.4 mg/kg of body mass) and beetroot (1.5-2.0 mg/kg). Taking into account the nitrate levels in water and milk a daily consumption of nitrates in preschool children was higher than daily permissible level.

Animals↗

PubMedDate not supplied

Liquid chromatographic determination of free glutamic acid in soup, meat product, and Chinese food: interlaboratory study.

An interlaboratory study of the liquid chromatographic (LC) determination of free glutamic acid in soup, meat product, and Chinese food was performed. Homogenized food samples were extracted with hot water, filtered, and diluted. Aliquot portions were treated with N,N-dimethyl-2-mer-capto-ethyl-ammonium chloride (DMMAC) and o-phtaldialdehyde (OPA) to convert glutamic acid to a stable fluorescent complex. After LC separation on a reversed-phase C18 column with acetonitrile-phosphate buffer (pH 7.0)-water (80 + 180 + 740, v/v) as mobile phase, glutamic acid peaks were measured fluorometrically (excitation, 340 nm, and emission, 389 and/or 440 nm). Homocysteic acid was used as internal standard. Twelve samples (6 blind duplicates) containing about 0.3-1.3% (w/w) of glutamic acid were analyzed singly by 12 laboratories. Results from one participant were excluded. Repeatability relative standard deviations (RSDr) varied from 1.3 to 4.5%, and reproducibility relative standard deviations (RSDR) ranged from 4.1 to 7.1%. Average recovery of glutamic acid determined at 6 levels was 101.5% (range, 98-106%).

Chromatography, Liquid↗

PubMed1992

Laboratory performance in a food microbiology proficiency testing scheme.

Results from two shipments in a proficiency testing scheme in which almost 200 food microbiology laboratories participated are summarized. Freeze-dried mixtures of bacteria were used as simulated food samples. Four and six samples, respectively, were examined. The statistical procedures used to evaluate the performance of participating laboratories are described. It is shown that laboratories which had been in the scheme for a long time perform, on average, better than those that had been in the scheme for a short time. The former laboratories produced fewer false and outlying results, and were more accurate and precise in their determinations.

Bacteria↗

PubMed2002

[Enterotoxic strains of Clostridium perfringens and sporulation].

Clostridium perfringens strains of A type capable of enterotoxin (CPE) synthesis may be a potential source of food-poisoning. Suitability of methods for CPE detection on the protein level is limited by difficulties in inducing sporulation in vitro. A number of unknown facts concerning coregulation the sporulation processes and CPE synthesis are recognised. The goal of the work was to determine the level of correlation between CPE synthesis and spores formation. Enterotoxin and cpe gen were detected by RPLA after sporulation induction test and by methods based on amplification on the DNA and mRNA levels. Sixty-four C. perfringens strains of A type isolated from patients with food poisoning symptoms and from food samples were analysed. Collection of isolates was differentiated as not enterotoxic, enterotoxic, and potentially enterotoxic strains based on appropriate strain profile: plc(+), cpe(-), CPE(-); plc(+), cpe(+), CPE(+); and plc(+), cpe(-), CPE(-), respectively. No significant difference between expression of cpe mRNA in vegetative and sporulation phase was found. The obtained results indicate that sporulation is not an essential factor for cpe gene expression.

Base Sequence↗

PubMed1998

Dietary boron intakes of selected populations in the United States.

Knowledge of daily boron (B) intakes will assist researchers in establishing B requirements and elucidating the metabolic role of B in humans. B concentrations in commonly consumed foods were utilized to approximate the B intake of selected US populations. Triplicate food samples were digested at low temperatures with 16 M HNO3 and 30% H2O2, and analyzed by inductively coupled plasma spectroscopy (ICP). Milk and dairy products, juices, and beverages were the largest contributors to dietary B. Total B content of average daily diets ranged from 548 microg for toddlers (2 yr old) to 883 microg for mature males (60-65 yr old), excluding tap water contributions. Toddlers consumed 3.7 times more B than mature males when adjusted for body weight (body wt) and consumed the diet with the highest boron density (1.8 microg/kJ or 0.43 microg/kcal). Adolescent females consumed a diet with the lowest B density (1.12 microg/kJ or 0.26 microg/kcal). Food B concentrations applied to diet records (1020 microg/d) and ICP analysis of the corresponding food composites (1170 microg/d) were comparable (p < 0.05). Current estimations of B in US diets are consistent with reports in the literature stating that normal adult daily B intakes are approx 1 mg.

Adolescent↗

PubMed2002

Enteric bacteriophages as potential fecal indicators in ground beef and poultry meat.

Recovery efficiencies of enteric bacteriophages (F+ RNA coliphages, somatic coliphages, and Salmonella phages) as alternative fecal indicators were determined from ground beef and chicken breast meat using amino acid eluants (glycine and threonine) and a complex eluant (3% beef extract). Levels of F+ RNA coliphages (MS2, GA, Qbeta, FI, and SP), the somatic coliphage phiX174, and three environmental isolates of Salmonella phages (isolated from raw sewage) were assayed using three respective hosts: Escherichia coli Famp, E. coli C, and Salmonella Typhimurium. When 8% polyethylene glycol and 0.1 M NaCl were used to precipitate bacteriophages eluted with five different eluants, the highest recoveries of the three phage groups were with 0.5 M threonine and 0.25 M glycine-threonine. The average recoveries of F+ RNA coliphages, somatic coliphages, and the Salmonella phages from ground beef and chicken meat were 100, 69, and 65%, respectively, with threonine (0.5 M, pH 9.0) as the eluate. Of eight market food samples tested, F+ RNA coliphages were detected in five (63%) and somatic coliphages were detected in seven (88%). The overall detection sensitivity of the method was 3 PFU/100 g of ground beef or chicken meat. Levels of bacteriophages and bacterial indicators on chicken carcass surfaces were determined at identified critical control points at a poultry plant. Through the processing steps of evisceration, washing, and chilling, the levels of F+ RNA coliphages and fecal coliforms were reduced by 1.6 and 1.9 log10 PFU or CFU/100 g, respectively. F+ RNA coliphages and perhaps other enteric bacteriophages may be effective candidate indicators for monitoring the microbiological quality of meat, poultry, and perhaps other foods during processing. The bacteriophage concentration method developed provides a simple, rapid, and practical tool for the evaluation of fecal contamination levels in ground beef and processed chicken meat.

Animals↗

PubMed1980

Distribution of Serratia marcescens serotypes in cancer patients.

A study of 1314 patients with malignancies was made to determine the prevalence of Serratia marcescens in surveillance, diagnostic, and environmental cultures. Sera obtained from a commercial source were used to determine serotypic distributions of the S. marcescens strains isolated during a 51-month period. S. marcescens was isolated from 19% of patients with haematological neoplasms, from 5% of patients with lymphoma, and from 6% of those with solid tumours. Among carriers, rectal cultures were the commonest source in patients with lymphoma (32%); rectal and gingival cultures in patients with leukaemia (43% and 39%, respectively), and gingival cultures in patients with solid tumours (30%). Bacteraemias (.07%) were infrequent sources. Although seldom isolated from environmental or food samples, S. marcescens may occasionally be abundant in fresh fruit and vegetables. Serotyping of 220 strains of S. marcescens demonstrated 38 distinct antigenic types. The predominant serotype, O14:H12, was present in the upper respiratory tract of half of the persons who carried this serotype. Serotyping is a readily reproducible method of subspeciating S. marcescens; it can be satisfactorily used as an epidemiological tool.

Bacteriuria↗

PubMed2003

A food-borne outbreak caused by Salmonella enteritidis.

This study was designed to define the epidemiology of a food-borne outbreak caused by Salmonella enteritidis that affected only one squadron of a military battalion located in the vicinity of the city of Edirne in Turkey. The outbreak was analyzed by a standard surveillance form of the Centers for Disease Control and Prevention. The relationship between the eaten foods and cases was analyzed by Fisher's exact chi-square test, and odds ratios were calculated by a case-control study. The outbreak affected 60 of 168 soldiers in the squadron, 16 of whom were hospitalized. S.enteritidis was cultured in stools from 13 of the hospitalized soldiers and from 3 soldiers who had prepared the food. All strains were completely susceptible to antibiotics; their plasmid profiles were also identical. The highest attack rate detected was 55.7% in an omelet eaten 24 hours before (p < 0.001). Furthermore, it was the riskiest food according to the case-control study (OR=7.88; 95% CI=3.68-16.89). The food samples were unobtainable because they had been discarded. All of the hospitalized cases recovered, and none of the control cultures of stools yielded the pathogen after three weeks. In conclusion, although our results didn't indicate the exact source of the outbreak microbiologically, the omelet was considered to be the source based on the epidemiological proofs.

Disease Outbreaks↗

PubMedDate not supplied

Improvement of calibration curve for determining peroxide values of food lipids by the modified ferrous oxidation-xylenol orange method.

The linearity range of the standard Fe(+3) calibration curve for measuring lipid hydroperoxides in food samples by the modified ferrous oxidation-xylenol orange (mFOX) method was extended from 5-20 micrograms to 2-40 micrograms by establishing the best concentration of xylenol orange in the same assay system. Butter, fish oil, and some vegetable oils were analyzed by the International Dairy Federation method and the improved mFOX method, and results were compared.

Absorption↗

PubMed2003

Verocytotoxin-producing Escherichia coli in foodstuffs of animal origin.

While much research effort has been targeted at the verocytotoxin-producing Escherichia coli (VTEC) serotype O157:H7, it is becoming more evident that other VTEC serotypes can also be associated with human foodborne disease. An increasing number of these non-O157 serotypes have been isolated from food sources and from humans suffering from haemolytic-uraemic syndrome and diarrhoea. The aim of our work was to investigate the prevalence of VTEC O157 and non-O157 in foodstuffs of animal origin using two rapid enzymatic procedures. Various types of food samples, 352 in total, were tested: 233 with the Premier EHEC, a screening test which directly detects the presence of verocytotoxin, regardless of serotype, while 119 of these with the Vidas ECO, which is a specific screening test for E. coli O157:H7, together with the Premier EHEC. Two samples were positive for VTEC, one of serogroup O126 and the other was non-serotypable. Another sample was positive in the test specific for E. coli O157:H7, but was not confirmed by culture. This study suggests that VTEC strains are not prevalent in Italy, and that the isolation of serogroup O157 is relatively infrequent. This leads us to conclude that there is little chance of exposure to pathogen for the average consumer in Italy.

Animals↗

PubMed1976

Evaluation of an automated fluorescent antibody procedure for detection of Salmonella in foods and feeds.

A prototype automated system using fluorescent antibody (FA) was evaluated for rapid detection of salmonellae in foods. Samples were enriched in selenite cystine and tetrathionate broths. After incubation, both were transferred into fresh selenite cystine for a 4-h "post-enrichment" to dilute possible background fluorescence from product. These cultures were then analyzed automatically, and results were compared with those obtained by the methods of the Association of Official Analytical Chemists (AOAC). Initially, 167 samples of milk powder, dried yeast, and imported frog legs were examined. The AOAC and automated FA methods correlated well with all samples but frog legs. Difficulty with the latter was caused by procedural and mechanical problems coupled with high numbers of competing microorganisms in post-enrichment cultures. Modification of procedure and partial redesign of equipment corrected these difficulties, and excellent correlation was obtained with another 116 frog leg samples. All 89 AOAC-confirmed positives were also detected by the automated FA method, and there were only 4% false FA positives. The system shows potential for screening products for salmonellae; however, all positives should be confirmed by manual biochemical and serological methods.

Animal Feed↗

PubMed2005

Identification and characterization of anthocyanins by high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry in common foods in the United States: vegetables, nuts, and grains.

Anthocyanins in common foods in the United States, other than fruits and berries, were identified and characterized by high-performance liquid chromatography (HPLC)-electrospray ionization-tandem mass spectrometry coupled with diode array detection. Of all of the 40+ vegetables, nuts, and grains screened, seven vegetables, one nut, and one grain were found to contain anthocyanins; the number of anthocyanins detected varied from two in pistachio nuts to 34 in red radishes. The individual anthocyanins were identified by comparing their mass spectrometric data and retention times with those of standards, published data, and reference food samples. In all of the samples analyzed, except for sorghum, only six common anthocyanidins (delphinidin, cyanidin, pelargonidin, petunidin, peonidin, and malvidin) were found as their glycosides. Anthocyanins in certain vegetables such as red cabbage and red radish were highly conjugated with sugars and acylated groups, and thus, their structures were very complicated. Eight different either aliphatic or aromatic acylated groups (acetoyl, coumaroyl, malonoyl, p-hydroxybenzoyl, feruoyl, caffeoyl, sinapoyl, and oxaloyl) were identified in the anthocyanins. In addition to glucose, six other sugar moieties (galactose, xylose, rhamnose, rutinose, sambubiose, and laminaribiose) were observed. Three varieties of sorghum were found to contain 3-deoxyanthocyanidins and their derivatives as major anthocyanins. A number of new anthocyanins were identified in the foods studied. This paper presents complete HPLC profiles and MS spectrometric data, obtained under the same experimental conditions, for common vegetables, pistachio nuts, and sorghum that contain anthocyanins.

Anthocyanins↗

PubMed2001

Reaction of tryptophan with carbohydrates: identification and quantitative determination of novel beta-carboline alkaloids in food.

The formation of various carbohydrate-derived beta-carbolines was observed when model reactions of tryptophan with glucose were studied by means of HPLC with diode array detection, as well as by means of HPLC-MS. Isolation of these compounds and subsequent characterization by tandem mass spectrometry and NMR spectroscopy led to the identification of diastereomeric 1-(1,3,4,5-tetrahydroxypent-1-yl)-9H-pyrido[3,4-b]indoles (1a/b), 1-(1,4,5-trihydroxypent-1-yl)-9H-pyrido[3,4-b]indoles (2a/b), and E/Z isomers of 1-(1,5-dihydroxypent-3-en-1-yl)-9H-pyrido[3,4-b]indole (3a/b). HPLC-MS was used to prove the presence of these novel beta-carboline alkaloids in various food samples. In addition, quantitative determination of beta-carbolines 1a, 1b, and 2a/b in numerous products was achieved by means of HPLC with fluorometric detection. Concentrations ranged from 12 to 1922 microg/L for 1a and 1b and from 3 to 644 microg/L for 2a/b. The highest concentrations of all carbohydrate-derived beta-carbolines under study were found in ketchup, soy sauce, and fish sauce.

Alkaloids↗

PubMed2001

Survival of poliovirus on soft fruit and salad vegetables.

A series of studies were performed, using poliovirus, to ascertain the potential for enteric pathogenic viruses to survive on various foodstuffs. The extraction protocols, which could be performed in just a few hours, were developed for use with quantities of food that would normally constitute a portion for consumption. The protocols were based on elution of viruses from food surfaces, followed by differential centrifugation to remove food debris and concentrate viruses. The studies were mostly performed using fresh produce stored at refrigeration temperature for 2 weeks or so, which was considered to represent the maximum time elapsing between purchase and consumption. Each food sample was inoculated with a viral suspension, and samples were analyzed immediately and at intervals throughout the experiment. Statistical analyses were performed on the results, and the decimal reduction times (D-values), or number of days after which the initial virus numbers had declined by 90%, were calculated. In summary, the resulting D-values were as follows: lettuce, 11.6 days; green onion, no decline; white cabbage, 14.2 days; fresh raspberries, no decline; and frozen strawberries, 8.4 days. The results showed that enteric viruses may persist on fresh fruit and vegetables for several days under conditions commonly used for storage in households. Therefore, if contamination has occurred before purchase, there will always be a risk of infection from consumption of the food.

Food Handling↗

PubMed2000

Occurrence of enterotoxigenic Aeromonas species in foods.

Out of a total of 246 food samples of animal origin screened for isolation of Aeromonas spp., 33 (13.41%) were positive for these organisms. Maximum positivity was shown by the samples from fish (28.57%), followed by poultry meat (16.67%), poultry eggs (12.50%), goat meat (12%), buffalo meat (7.69%) and cow milk (5.56%). A. hydrophila was the predominant species (51.52%) followed by A. sobria (39.39%) and A. caviae. Of these, 70.59% A. hydrophila, 69.23% A. sobria and 33.33% A. caviae showed enterotoxigenic reaction in mouse paw oedema test.

Aeromonas↗

PubMed1997

The coenzyme Q10 content of the average Danish diet.

The average dietary intake of coenzyme Q10 and coenzyme Q9 of the Danish population was determined, based on food consumption data from a national dietary survey. Selected food items in edible form were analyzed for the coenzyme Q content by HPCL with UV-detection, and their contribution to the total intake calculated. The effect of cooking was a 14-32% destruction of coenzyme Q10 by frying, and no detectable destruction by boiling. The average coenzyme Q10 intake of the Danish population was estimated to 3-5 mg/day, primarily derived from meat and poultry (64% of the daily intake), while cereals, fruit, edible fats, and vegetables only make minor contributions. The intake of coenzyme Q10 is approximately 1 mg/day, primarily derived from vegetable fats and cereals. The alpha-tocopherol content of the selected food samples was analyzed by HPLC with fluorescence detection, and the calculated average intake of alpha-tocopherol was comparable to the estimate from the dietary survey (7-8 vs. 7.4 mg alpha-tocopherol/day, respectively). The commercially available dietary supplements (capsules) provide 10-30 mg CoQ10/day, thus the average diet. The optimal dietary intake of coenzyme Q10 is unknown.

Animals↗

PubMed1998

Polymerase chain reaction for rapid detection of Campylobacter jejuni in artificially contaminated foods.

Campylobacter jejuni was inoculated into a range of raw and ready-to-eat foods. These food samples were used as a test source for detection of this bacterium by the polymerase chain reaction (PCR). Specific detection of Camp. jejuni, as indicated by a PCR product of 159 bp, was possible with all pre-cooked deli-sliced and raw poultry products tested. All vegetables tested were compatible with the PCR assay. Cantaloupe, kiwi and pineapple tested positive while strawberries, watermelon, grapes and apples tested negative. By using a nested PCR assay that yields a single band at 122 bp, positive results were obtained with watermelon and grapes while the apple and strawberries continued to give a negative reaction. These rapid and specific assays for Camp. jejuni are compatible with most foods in insuring the safety of the food product.

Animals↗

PubMedDate not supplied

Fluorogenic assay for rapid detection of Escherichia coli in chilled and frozen foods: collaborative study.

A collaborative study was conducted to compare a proposed LST-MUG method with the AOAC official method for Escherichia coli detection. E. coli produces an enzyme, beta-glucuronidase, which cleaves the substrate, 4-methyl-umbelliferyl-beta-D-glucuronide (MUG), to yield a fluorescent end product. Incorporation of the MUG substrate into lauryl tryptose broth (LST) enables a rapid quantitative method for screening E. coli, which is detected by fluorescence of the medium under longwave UV light. In this collaborative study, 5 food samples, 2 frozen (entree sauce/gravy and dairy topping) and 3 chilled (hamburger, pork sausage, and cheese), were tested for E. coli detection by 17 collaborating laboratories. Results indicate that the LST-MUG method is equal to or better than the current AOAC method for detecting E. coli. The LST-MUG method has been adopted official first action.

Animals↗