SEARCH · PubMed Health

Results for “Food samples”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,027 records · Page 57Linked to original sources

PubMed2001

Derivative spectrophotometric determination of 5-(hydroxymethyl)-2-furaldehyde (HMF) and furfural in Locust bean extract.

Furfural and 5-(hydroxymethyl)-2-furaldehyde (HMF) are useful indicators of accurate storage temperature of food samples. A first derivative spectrophotometric method was developed for the determination of the furfural and HMF level in Locust bean pekmez. In addition, the levels of the furfural and HMF were investigated during Locust bean pekmez preparation. The recoveries were generally nearly 100%. This method is also rapid and accurate and results in economical analyses of furaldehydes.

Fabaceae↗

PubMed1999

An enzymatic cycling method using pyruvate orthophosphate dikinase and firefly luciferase for the simultaneous determination of ATP and AMP (RNA).

A novel bioluminescent enzymatic cycling assay for ATP and AMP with concomitant use of firefly luciferase and pyruvate orthophosphate dikinase (PPDK) was developed. In this system, AMP and pyrophosphate produced from ATP by firefly luciferase were converted back into ATP by PPDK. This resulted in constant luminescence once the stable phase had been reached. Background luminescence of the reagent was reduced with adenosine phosphate deaminase by degrading ATP and AMP in the reagent. The maximum recycling ratio calculated from the integrated luminescence value was 2.64 cycles/min. The measurable ranges for ATP and AMP were equal and were between 4 x 10(-13) and 4 x 10(-17) mol/assay. The amount of yeast RNA could be estimated in the range of 1 x 10(-8) to 1 x 10(-12) g/assay by estimating the amount of AMP resulting from the degradation of RNA with nuclease P1. Various food samples were subjected to measurement of the amount of ATP + AMP + RNA to provide an index for hygiene monitoring. For beef extract, sensitivity was improved by more than 20 million compared to the previous methods relying only on the amount of ATP as an index.

Adenosine Deaminase↗

PubMed2001

Rapid detection of Listeria monocytogenes in foods, by a combination of PCR and DNA probe.

Listeria monocytogenes is a frequent contaminant of water and foods. Its rapid detection is needed before some foods can be prepared for marketing. In this work L. monocytogenes has been searched for in foods, by a combination of polymerase chain reaction (PCR) and a DNA probe. Both PCR and the probe were prepared for recognizing a specific region of the internalin gene, which is responsible for the production of one of the most important pathogenic factors of Listeria. The combined use of PCR and the DNA probe was used for the detection of L. monocytogenes in over 180 environmental and food samples. Several detection methods were compared in this study, namely conventional culture methods; direct PCR; PCR after an enrichment step; a DNA probe alone; a DNA probe after enrichment and another commercially available gene-probe. Finally PCR and the DNA probe were used in series on all the samples collected. When the DNA probe was associated with the PCR, specific and accurate detection of listeria in the samples could be obtained in about a working-day. The present molecular method showed some advantages in terms of rapidity and specificity in comparison to the other aforementioned tests. In addition, it resulted as being easy to handle, even for non-specialized personnel in small diagnostic microbiology laboratories.

Aged↗

PubMed1996

Luminescent Salmonella strains as real time reporters of growth and recovery from sublethal injury in food.

LuxA and luxB genes from V. harveyi carried by a Tn-5 containing plasmid were introduced into S. enteritidis by either conjugation or electroporation. Lux genes were used as a reporter to indicate the effects of heat treatment (50 degrees C, 55 degrees C and 65 degrees C) and pH (from 1 to 7) on the survival, growth and recovery of Salmonella cells. When a luminescent S. enteritidis strain, obtained by electroporation, was subjected to a plasmid curing procedure, the resulting culture lost the plasmid but remained luminescent. Southern hybridization was performed to determine the location of lux genes in S. enteritidis cells. The light output from recombinant cultures with different gene locations was compared and found to be higher for strains in which the luciferase was plasmid-mediated. The luminescent Salmonella culture was inoculated in food samples such as homogenized chicken meat, whole liquid eggs and fluid milk and development of luminescence with time was monitored. The minimum number of Salmonella cells required for positive observation was approximately 1 x 10(2) CFU/ml in broth and homogenized meat cultures, 2 x 10(3) CFU/ml in fluid milk and 7 x 10(3) CFU/ml in whole liquid egg.

Food Microbiology↗

PubMedDate not supplied

Nosocomial infections by Listeria monocytogenes: analysis of a cluster of septicemias in immunocompromised patients.

From December 1994 to November 1995 an unusual accumulation of Listeria infections occurred at the University Hospital Hamburg-Eppendorf, Germany. Eleven immunosuppressed patients from different departments developed septicemia due to Listeria monocytogenes during hospitalization. In a retrospective study, serotyping and pulsed-field gel electrophoresis revealed that six isolates were identical or genetically related. Four of them had been isolated from renal transplant recipients. Listeria monocytogenes was neither detected in food samples of the renal transplantation ward, nor in stool specimens obtained from the ward staff. There had been no close contacts among the infected patients. Before transplantation, the renal transplant recipients had been dialysed in different dialysis centers. Nosocomial foodborne transmission could not be proven but seems likely.

Adult↗

PubMed1997

The lipoxygenase sensor, a new approach in essential fatty acid determination in foods.

Both an enzyme electrode and enzyme column with immobilized lipoxygenase, respectively, were used for the determination of essential fatty acids. The former was applied in a batch system, the latter was part of a fully automated flow injection analysis (FIA)-system. The oxygen consumption due to the lipoxygenase catalysed oxygenation of essential fatty acids was monitored amperometrically. Both systems were compared with regard to linear ranges of the calibration plots, sensitivities, detection limits, apparent Michaelis-Menten constants and lifetimes. The enzyme electrode showed different sensitivities for linoleic and alpha-linolenic acids, the most common essential fatty acids. The reason for this was not a second oxygenation step by lipoxygenase in case of alpha-linolenic acid, but a different dialytic behaviour of the two substrates. Hence, only the FIA-system was used for the determination of these fatty acids in real matrices such as vegetable oils and margarines. In the presence of detergent the triglycerides of the hydrophobic food samples were converted into water soluble glycerol and free fatty acids by a 15 min incubation with a ready to use lipase/esterase-mix, thus avoiding the use of organic solvents for analysis. Results obtained by the enzymatic FIA-system were in excellent agreement with those obtained by standard gas chromatography.

Biosensing Techniques↗

PubMed2004

Karyomegaly of tubular kidney cells in human chronic interstitial nephropathy in Tunisia: respective role of Ochratoxin A and possible genetic predisposition.

Karyomegalic nephropathy associated to bizarre enlargement of nuclei in renal tubular epithelial cells was first described by Mihatch in 1979. We present herein additional cases occurring in three siblings suffering from chronic interstitial nephropathy (CIN) of unknown aetiology where the renal biopsies showed numerous enlarged and hyperchromatic nuclei. CIN of unknown aetiology has been previously characterized and showed striking similarities with Balkan Endemic Nephropathy (BEN). Ochratoxin A (OTA) is a nephrotoxic mycotoxin suspected to be the causal agent of the BEN as well as the Tunisian CIN of unknown aetiology. OTA is incriminated in the onset of these disclosed cases of karyomegalic nephropathy since high OTA concentrations were found in blood (505.83 ng/ml, 102.63 ng/ml and 1023 ng/ml) and in urine (94.40 ng/ml and 10.18 ng/ml) of two of them. Moreover, we have investigated OTA in blood and urine as well as in food samples of the entire household (21 people). Our findings suggest (i) a link between OTA and the outcome of this karyomegalic nephropathy, and (ii) the possible involvement of a genetic factor since the three cases have the same haplotype B27/35.

Adult↗

PubMed1979

Antibiotic resistance of salmonellae in Czechoslovakia -- situation and prospects.

Antibiotic resistance of non-typhoid Salmonellae is in Czechoslovakia continuously monitored by a computer and its transferability is studied, on an all-nation level, within the Federal Plan of Scientific Investigation and Development. Restance and its transferability was surveyed in strains of Salmonella from humans, from farm animals, from the food chain as well as from surface and waste waters. Proportion of antibiotic-resistant Salmonella strains did not, in general, increase during the four-year period of 1973 to 1977. While resistant strains from humans as well as farm animals show a high degree of transferability, strains from food samples lack, in general, the transfer ability. This might be inferred that strains causing human salmonellosis which are carried to man trough foodchain, gain their character of transferability directly in the gut, i.e. from E. coli strains, and mainly due to presence of therapeutically given antibiotics.

Animals↗

PubMed2004

Development of an indirect competitive ELISA for detection of Campylobacter jejuni subsp.jejuni O:23 in foods.

An indirect enzyme immunoassay for rapid detection of Campylobacter jejuni subsp. jejuni 0:23 has been developed. Optimum concentrations of immobilized cells, polyclonal chicken IgY, and rabbit anti-IgY antibody-horseradish peroxidase conjugate were 3.1 CFU/nL, 10 microg/mL, and 8 microg/mL, respectively. Under such conditions, the detection limit reached 50 CFU/microL, limit of quantification being 480 CFU/microL. By testing 5 chromogens, viz. 1,2-benzenediamine, 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonic acid), 3,3',5,5'-tetramethylbenzidine, bi(4,4'-anisidine) and 3-methyl-2-benzothiazolinone hydrazone, in horseradish peroxidase substrate, 1,2-benzenediamine or 3,3',5,5'-tetramethylbenzidine as H-donors in the enzyme substrate provided the highest ELISA sensitivity. The applied polyclonal antibody was specific for homogeneous antigen. The cross-reactions were observed only with one strain of C. sputorum subsp. sputorum (21.5 %) and with G+ bacterium Micrococcus luteus (6.1 %). Preliminary tests have been performed with a limited number of artificially contaminated food samples. No matrix effects on the ELISA sensitivity were observed. The results (by means of ELISA) were comparable with those given by both a standard cultivation method performed according to CSN ISO 10272 and commercially available Singlepath Campylobacter GLISA-Rapid Test.

Animals↗

PubMed2003

Palatability, food intake and the behavioural satiety sequence in male rats.

Food intake is influenced not only by nutritional status but also by diverse environmental factors. Indeed, a unique quality of food reward is its strong modulation by palatability cues, such as taste, with animals generally preferring diets that are sweet and avoiding those that are either bitter or sour. As appetite suppressants (including those currently in development) could alter food intake by modifying taste sensitivity and/or palatability, the aim of the present study was to characterise the influence of taste adulteration on the normal structure of feeding behaviour, i.e., the behavioural satiety sequence (BSS). Adult male rats were initially habituated both to the basic test diet (mash) and the test arena. Following stabilisation of basal intake, a continuous monitoring technique was used to profile behaviour in weekly 1-h sessions during which the animals were presented, in counterbalanced order, with the basic diet (control) or one of four taste-adulterated variants (0.015% quinine, 0.04% quinine, 0.2% saccharin, 0.3% saccharin). Food intake was strongly suppressed by the higher quinine concentration but was not significantly altered by any of the other additives. Behavioural analysis revealed that this anorectic-like response to 0.04% quinine-adulterated food was associated with a significant reduction in the peak feeding response, highly atypical intermittent food sampling/digging and the virtual absence of resting behaviour. Importantly, this pattern of behavioural change is readily distinguishable from those seen in response to other manipulations that reduce intake, including selective anorectics, sedatives and psychostimulants. Despite the lack of significant effect on food intake or the duration of feeding behaviour, dietary adulteration with 0.015% quinine (and, to a lesser degree, 0.3% saccharin) produced some effects on behavioural structure/time course consistent with a mild aversive response, i.e., bouts of midsession food sampling and a delay in the transition from eating to resting. Data are discussed in relation to the specific behavioural signature to quinine-induced anorexia and its potential utility in identifying appetite suppressants that may modify intake via changes in taste sensitivity and/or palatability.

Animals↗

PubMed2004

Limitations to successful investigation and reporting of foodborne outbreaks: an analysis of foodborne disease outbreaks in FoodNet catchment areas, 1998-1999.

To better understand factors associated with confirming the etiologic organism and identifying the food vehicle responsible for foodborne-disease outbreaks, we examined data from outbreaks reported in 1998 and 1999 through active surveillance by Foodborne Disease Active Surveillance Network (FoodNet) surveillance areas in 7 states. In 71% of these outbreaks, no confirmed etiology was identified, and in 46%, no suspected food vehicle was identified. Outbreaks involving > or =10 cases were significantly more likely to have their etiology identified than were smaller outbreaks. In two-thirds of outbreaks in which an etiology was not confirmed, no stool specimens were collected for laboratory testing; in 55% of these outbreaks, neither clinical specimens nor food samples were tested. If the etiology of and factors contributing to foodborne-disease outbreaks are to be understood, adequate resources must be available to allow specimens to be collected and tested and epidemiologic investigations to be conducted appropriately.

Disease Outbreaks↗

PubMed1971

Bacteriology of dehydrated space foods.

The initial bacteriological requirement established in 1964 for space foods by the U.S. Army Natick Laboratories are: a total aerobic plate count (</= 10,000 per g), a total coliform count (</= 10 per g), fecal coliforms (negative per gram), fecal streptococci (</= 20 per g), coagulase-positive staphylococci (negative in 5 g) and salmonellae (negative in 10 g). Of the space foods and prototypes tested during 1968 and 1969, 93% complied with the total aerobic plate count, 98% had less than 1 coliform per g, and 99% were negative for fecal coliforms; 88% complied with the streptococci requirement; 100 and 98% were negative for staphylococci and salmonellae, respectively. Nineteen food samples which did not comply (as indicated parenthetically by actual counts per gram) with the requirements were (i) total aerobic plate count: beef soup and gravy base (18,000), chicken soup and gravy base (57,000), spaghetti with meat sauce (12,100 and 14,000), sugared coffee (> 300,000), chocolate ice cream cubes (20,000), and each of four samples of chocolate candy (12,000 to 61,000); (ii) coliforms: two out of three vanilla milk drinks (16 and 127) and one beef hash bar (14); (iii) fecal coliforms: one sample of chicken soup and gravy base positive; (iv) fecal streptococci: two samples of peanut cubes (40 and 108), coconut cubes (75), chicken soup and gravy base (2,650), beef soup and gravy base (33), and five out of six flavored milk drinks (23 to 300); (v) salmonellae: one each of chicken and beef soup and gravy base were positive.

Aerobiosis↗

PubMed1991

Evaluation of an enzymatic method for fast identification of Listeria spp. in cheese and meat products.

Listeria-Tek ELISA was compared with conventional cultural procedure of FIL/IDF (Federation International de Laiterie/International Dairy Federation) modified by us. The ELISA assay is able to detect Listeria innocua, Listeria monocytogenes, Listeria murrayi and Listeria welshimeri, after 48 h in artificially contaminated cheeses. No specific reactions, no false positive or negative were detected and the assay has a high correlation with the conventional method used in this research. We also analyzed meat products and cheeses and identified Listeria spp. and Listeria monocytogenes serotypes. In 313 food samples examined there were only 3 false positives. With ELISA Kit we obtained 0.9% more than with the cultural method and the percentage of false positives is 1.6%. So in commercial products the total absence of false negatives demonstrates the great sensitivity of the method in respect to investigated microorganisms. As determined by cultures 218 samples contained 47 Listeriae monocytogenes, 67 Listeriae innocua, 21 Listeriae welshimeri, 7 Listeriae ivanovii, 3 Listeriae murrayi and 3 Listeriae denitrificans. Listeria monocytogenens includes serotypes 1 (13) and serotypes 4 (14). 20 Listeriae monocytogenes were serotyped by polyantisera Difco (Detroit, Michigan).

Animals↗

PubMed1996

Isolation and characterization of bacteriocin-producing lactic acid bacteria from ready-to-eat food products.

Lactic acid bacteria isolated from a range of foods sold in ready-to-eat form were screened for bacteriocin production. Twenty-two bacteriocin-producing cultures were isolated from 14 of the 41 foods sampled. Bacteriocin-producing isolates from meat, fish and dairy products were Lactobacillus and Leuconostoc species typically found associated with these products. Most of these isolates gave only a narrow inhibitory spectrum although two showed activity against Listeria monocytogenes. Fruit and vegetable products gave a broader range of organisms but most of the bacteriocin-producing cultures were found to be strains of Lactococcus. Several lactococci produced a nisin-like activity, and showed a broad inhibitory spectrum against the indicator strains tested. The ease with which bacteriocin-producing strains could be isolated implies that they are already being safely consumed in food, and highlights the potential for using bacteriocin-producing cultures for biopreservation, especially in association with minimally processed products.

Bacteriocins↗

PubMed2003

Trophallaxis in forager honeybees (Apis mellifera): resource uncertainty enhances begging contacts?

Trophallaxis among adult worker honeybees is the transfer of liquid food by mouth from one individual to another. Within the colony, nectar foragers perform offering contacts (as food-donors) to transfer the contents of their crops to recipient nest-mates and, in addition, they also perform begging contacts (as food-receivers). The biological relevance of these last interactions remains unknown. Previous evidence suggests that begging may be involved in the exchange of information on food resources that occurs naturally between employed foragers and nest-mates. This work was aimed to reveal possible connections between the information obtained while foraging and the begging behavior displayed inside the nest. Experiments were intended to (1) analyze whether chemosensory information obtained while foraging, i.e., odors and sucrose concentrations, affects begging behavior, and (2) determine whether resource uncertainty enhances begging contacts. Results showed that: (1) most begging contacts lasted less than 1 s, a duration which only allows receiving food samples from nest-mates; (2) the diversity of odors and sucrose concentrations at the feeding place enhances the occurrence of begging contacts; and (3) an increased resource uncertainty enhances the forager begging behavior. In addition, results suggest that foragers may direct their begging contacts frequently to other employed nectar foragers.

Animal Communication↗

PubMed2006

[Characteristic of Listeria spp. bacteria isolated from food products].

The frequency of occurrance of Listeria strains in different food products was determined. Biochemical characteristic of the isolated strains was achieved in accordance with procedure included in PNEN ISO 11290 standard, genus was determined byApiListeria (bioMéieux) test. Sensitivity to selected antibacterial medicines was investigated using disck method and Mueller-Hinton 2 Agar medium. From the 577 examinated food samples 126 strains of Listeria were isolated and among them: 34.1% L. monocytogenes, 36,5% L. welshimeri, 19.0% L. innocua, 3.17% L. grayi, 0.79% L. seeligeri, 0.79% L. seeligeri/welshinmeri and 5.56% L. ivelshimeri/innocua. L. monocytogenes strains most often were found in minced pork, culinary products and in frozen vegetables. On the base of ApiListeria (bioMéieux) test the isolated L. monocytogenes strains were qualified into 2 biochemical types. It was found that all L. monocytogenes were sensitive to sulphametaksazol/trimetoprim and ampicyllin, 25% of strains were moderatety sensitive to penicillin and only 2 L. monocytogenes strains were resistant to gentamicin. Presence of Listeria spp. microorganisms in food products may be an production hygiene indicator for critical control point and show the possibility of contamination with L. monocytogenes strains.

Animals↗

PubMed1970

One-day fluorescent-antibody procedure for detecting salmonellae in frozen and dried foods.

The indirect fluorescent-antibody technique was used to examine 422 food samples for the presence of salmonellae. A cultural phase involving a 16-hr preenrichment in buffered nutrient broth-milk medium followed by a 4- to 5-hr subculture into fresh medium of the same composition was evaluated. This procedure yielded a sufficient population of salmonellae so that no false-negative results were obtained. Of the 31 false-positives obtained, 12 samples yielded positive cultural results upon extensive subculture of the original enrichment broths. Yeast cells and both vegetative and spore forms of bacilli were observed to fluoresce when stained with anti-Salmonella serum. Efforts to ascertain the cause of these cross-reactions and several alternate explanations are discussed.

Animals↗

PubMed1971

New quantitative, qualitative, and confirmatory media for rapid analysis of food for Clostridium perfringens.

A selective and differential medium, Shahidi-Ferguson Perfringens agar (SFP agar), and a confirmatory medium, lactose-motility agar (LM agar), were developed for the enumeration and identification of Clostridium perfringens in foods. These media provide a rapid, specific, and direct diagnosis of C. perfringens. SFP agar contains sodium metabisulfite and ferric ammonium citrate to demonstrate H(2)S production and egg yolk to demonstrate lecithinase production by C. perfringens. On SFP agar, C. perfringens produces black colonies, 2 to 3 mm in diameter, surrounded by zones of opaque precipitate. The typical colonies are confirmed on LM agar. Enumeration and identification are completed within 48 hr. All of the ingredients of SFP agar are stable to heat and storage conditions. SFP agar also contains two antibiotics, kanamycin and polymyxin B, which are inhibitory to many bacteria commonly occurring in foods. A comparative study of SFP agar and noninhibitory media showed that SFP agar did not inhibit any of the 16 strains of C. perfringens tested. Recovery of C. perfringens added to foods averaged 90.6% for SFP agar as compared with 69.8% for sulfite polymyxin-sulfadiazine (SPS) agar (BBL) and 60.2% for SPS agar (Difco). The colonies on the SFP agar, were much larger and were consistently black. Of 464 food samples tested, C. perfringens was found in 27 samples with SFP agar and in 5 samples with SPS agar (Difco), with a recovery ratio considerably higher on SFP agar. SFP agar is a more specific presumptive medium for the enumeration of C. perfringens and in conjunction with LM agar should save considerable time, effort, and materials toward the final identification of the species.

Agar↗