Food Samples (food + sample)

Distribution by Scientific Domains


Selected Abstracts


SIMULTANEOUS DETECTION OF LISTERIA MONOCYTOGENES, STAPHYLOCOCCUS AUREUS, SALMONELLA ENTERICA AND ESCHERICHIA COLI O157:H7 IN FOOD SAMPLES USING MULTIPLEX PCR METHOD

JOURNAL OF FOOD SAFETY, Issue 3 2009
D. ZHANG
ABSTRACT In this study, one multiplex polymerase chain reaction (MPCR) assay was developed for simultaneous detection of four foodborne pathogens, i.e., Listeria monocytogenes, Staphylococcus aureus, Salmonella enterica and Escherichia coli O157:H7. Five specific primer pairs were designed based on the nucleotide sequences of hemolysin gene (hly) of Listeria monocytogenes, thermostable nuclease gene (nuc) of Staphylococcus aureus, invasion gene (invA) of Salmonella enterica, shiga-like toxin gene (stx) and intimin gene (eae) of Escherichia coli O157:H7 in this assay. The specificity and sensitivity of the MPCR method were validated, and the limit of detection (LOD) of this method was about 10 copies. One cfu/mL each of these foodborne pathogens spiked in practical food samples, i.e., ground meat, beef, pork, fish, shrimp, cheese, canola leaf and cabbage, could be detected simultaneously after 24 h enrichment at a rate of 87.5%, indicating that the established MPCR detection method was effective and suitable for practical use. PRACTICAL APPLICATIONS This study presents a quick and effective identification method to simultaneous monitor four foodborne pathogens in food samples. The specificity and sensitivity of this method can be used to unambiguously identify these four foodborne pathogens in practical food samples based on the species-specific genes. Therefore, this detection method is applicable for surveillance measures of these four foodborne pathogens in the food production chain. [source]


Voltametric and Flow Injection Determination of Oxytetracycline Residues in Food Samples Using Carbon Fiber Microelectrodes

ELECTROANALYSIS, Issue 7 2003
L. Agüí
Abstract A voltammetric method for the determination of the antibiotic oxytetracycline (OTC) in food samples is reported. Carbon fiber microelectrodes (CFMEs), which allow voltammetric measurements to be performed in a small volume (1,mL) of the analyte extract from the samples, are employed. Repeatable electroanalytical responses were obtained with no need of applying cleaning treatments to the CFME. Under the optimized square-wave conditions, a linear calibration plot for OTC was obtained in the 1.0×10,6,1.0×10,4,mol,L,1 range, with a detection limit of 2.9×10,7,mol,L,1 (150,ng,mL,1) OTC. The determination of OTC by a flow-injection method with amperometric detection using a homemade flow cell specially designed to work with CFMEs, was also evaluated using pure acetonitrile as the carrier. The SW voltammetric method was applied to the determination of OTC in spiked milk and eggs samples, at 100,ng,mL,1 and 200,ng g,1 levels, respectively. The procedure involved the extraction of the analyte in ethyl acetate, evaporation of the solvent and reconstitution of the residue in acetonitrile ,5.0×10,4,mol,L,1 tetrabutylammonium perchlorate medium. Recoveries of 96±8 and 91±8% were obtained for milk and eggs, respectively, by applying the standard additions method. [source]


Differential Kinetic Spectrophotometric Determination of Methamidophos and Fenitrothion in Water and Food Samples by Use of Chemometrics

CHINESE JOURNAL OF CHEMISTRY, Issue 3 2010
Na Deng
Abstract A spectrophotometric method for simultaneous analysis of methamidophos and fenitrothion was proposed by application of chemometrics to the spectral kinetic data, which was based upon the difference in the inhibitory effect of the two pesticides on acetylcholinesterase (AChE) and the use of 5,5,-dithiobis(2-nitrobenzoic acid) (DTNB) as a chromogenic reagent for the thiocholine iodide (TChI) released from the acetylthiocholine iodide (ATChI) substrate. The absorbance of the chromogenic product was measured at 412 nm. The different experimental conditions affecting the development and stability of the chromogenic product were carefully studied and optimized. Linear calibration graphs were obtained in the concentration range of 0.5,7.5 ng·mL,1 and 5,75 ng·mL,1 for methamidophos and fenitrothion, respectively. Synthetic mixtures of the two pesticides were analysed, and the data obtained processed by chemometrics, such as partial least square (PLS), principal component regression (PCR), back propagation-artificial neural network (BP-ANN), radial basis function-artificial neural network (RBF-ANN) and principal component-radial basis function-artificial neural network (PC-RBF-ANN). The results show that the RBF-ANN gives the lowest prediction errors of the five chemometric methods. Following the validation of the proposed method, it was applied to the determination of the pesticides in several commercial fruit and vegetable samples; and the standard addition method yielded satisfactory recoveries. [source]


Trans Fatty Acid Content of Selected Foods in an African-American Community

JOURNAL OF FOOD SCIENCE, Issue 6 2006
Z. Huang
ABSTRACT:,Trans fatty acid content was examined in several grocery foods and fast foods in an African-American community. Food samples were selected based on the frequency of use among this population group in the local community. Samples were collected 3 times with an interval of 1 wk. Total fat content was analyzed by Soxhlet method. Fatty acids profile, including trans fatty acids, was analyzed by GC,MS. In grocery foods, no trans fatty acids were detected in fish sticks, salad dressing, mayonnaise, muffin, and potato chips. Margarine contained the highest trans fatty acid at a level of 19.13%. The trans fatty acid level in crackers, cookies, butter, chicken patties, and biscuits mix ranged from 0.51% to 1.77%. In fast foods, no trans fat was detected in dressing. All the fried food and bakery food sampled in this study contain trans fat. The level varied from 2.07% to 10.30%. The principal trans fatty acid was trans 18:1. Other trans fatty acids found were trans 18:2, trans 19:1, and trans 16:1. In a total of 23 food samples, 16 of them were found to contain trans fatty acid. The results demonstrated that trans fat is commonly found in foods of the African-American community. The trans fatty acids content in tested samples varied from 0% to 19.13%. [source]


A small outbreak of listeriosis potentially linked to the consumption of imitation crab meat

LETTERS IN APPLIED MICROBIOLOGY, Issue 2 2000
J.M. Farber
A small outbreak of listeriosis involving two previously healthy adults occurred in Ontario. Food samples obtained from the refrigerator of the patients included imitation crab meat, canned black olives, macaroni and vegetable salad, spaghetti sauce with meatballs, mayonnaise and water. All of the samples except the water contained Listeria monocytogenes. The three most heavily contaminated samples were the imitation crab meat, the olives and the salad which contained 2·1 × 109, 1·1 × 107 and 1·3 × 106 cfu g,1, respectively. L. monocytogenes serotype 1/2b was isolated from the patients, as well as from the opened and unopened imitation crab meat. Molecular typing of the isolates by both randomly amplified polymorphic DNA (RAPD) and pulsed-field gel electrophoresis (PFGE) typing demonstrated the imitation crab meat and clinical strains to be indistinguishable. Challenge studies performed with a pool of L. monocytogenes strains showed that imitation crab meat, but not olives, supported growth of the organism. In this study we have shown for the first time the potential involvement of imitation crab meat in a small outbreak of listeriosis. In terms of disease prevention, temperature control is critical to prevent or reduce the growth of this foodborne pathogen. In addition, with refrigerated products having a long (> 30 d) shelf life, additional safety factors must be used to prevent the growth of foodborne pathogens such as L. monocytogenes. [source]


AEROBIC PLATE COUNTS OF PHILIPPINE READY-TO-EAT FOODS FROM TAKE-AWAY PREMISES

JOURNAL OF FOOD SAFETY, Issue 2 2005
MA. PATRICIA V. AZANZA
ABSTRACT The Aerobic Plate Counts (APCs) of some Philippine ready-to-eat (RTE) foods from take-away premises were established for the first time within the context of using the information for the development of Philippine microbial guidelines for RTE foods. The calculated APCs for most of the RTE foods analyzed in the study were ,,10,5 cfu/unit of food sample. Among the reasons cited to explain higher APC values were: use of raw ingredients for the final product, temperature abuse during vending, inadequate cooking and use of leftovers. It was recommended that the generally acceptable microbial guideline value for APC of RTE foods set at <,105 cfu/unit be adapted locally until more precise microbial criteria for this food type could be developed through an appropriate scientific process. [source]


Predictive Equations for Dielectric Properties of NaCl, D-sorbitol and Sucrose Solutions and Surimi at 2450 MHz

JOURNAL OF FOOD SCIENCE, Issue 6 2002
P. Yaghmaee And
ABSTRACT: Variation in dielectric properties of aqueous solutions with different concentrations and ratios of NaCl, D-sorbitol, and sucrose were investigated at 21 °C using the open-ended coaxial probe technique at 2450 MHz. Several equations to estimate dielectric properties of mixed or pure solutions were formulated. The equations were tested with other concentrations of solutions and surimi as a food sample containing the solutes. The correlation between the new measured dielectric properties and the calculated values were analyzed using a General Linear Model. The resultant prediction equations are suitable for pure and mixed aqueous solutions of (0 to 6%) NaCl, (0 to 18%) D-sorbitol and (0 to 60%) sucrose. For surimi, only loss factor was successfully predicted. [source]


Radiative heat exchange modeling inside an oven

AICHE JOURNAL, Issue 9 2009
Ashish Dhall
Abstract The 3D nongray radiative heat exchange in a near-infrared commercial oven is modeled. The spectrum is divided into into four gray bands to model the narrow wavelength range in which the halogen heat source radiates, the wavelength dependence of the food surface emittance, and the absorption coefficient of the heat source cover glass. The model is used to estimate the heating of a cuboidal food sample for 1 min at different cyclic settings of a halogen radiant heat source. The model predictions agree with the experimental data, and capture the cover-glass and the food-surface temperature and heat flux histories very well. The band-wise distribution of energy absorption by the food reveals the separate contributions from the source and the oven walls. Comparison of the heating rates between the measured non-gray food-surface and the different gray food-surface emittance values establishes the necessity of the nongray treatment. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source]


Development of an oligonucleotide microarray method for Salmonella serotyping

MICROBIAL BIOTECHNOLOGY, Issue 6 2008
B. Tankouo-Sandjong
Summary Adequate identification of Salmonella enterica serovars is a prerequisite for any epidemiological investigation. This is traditionally obtained via a combination of biochemical and serological typing. However, primary strain isolation and traditional serotyping is time-consuming and faster methods would be desirable. A microarray, based on two housekeeping and two virulence marker genes (atpD, gyrB, fliC and fljB), has been developed for the detection and identification of the two species of Salmonella (S. enterica and S. bongori), the five subspecies of S. enterica (II, IIIa, IIIb, IV, VI) and 43 S. enterica ssp. enterica serovars (covering the most prevalent ones in Austria and the UK). A comprehensive set of probes (n = 240), forming 119 probe units, was developed based on the corresponding sequences of 148 Salmonella strains, successfully validated with 57 Salmonella strains and subsequently evaluated with 35 blind samples including isolated serotypes and mixtures of different serotypes. Results demonstrated a strong discriminatory ability of the microarray among Salmonella serovars. Threshold for detection was 1 colony forming unit per 25 g of food sample following overnight (14 h) enrichment. [source]


Mechanistic study of membrane concentration and recovery of Listeria monocytogenes

BIOTECHNOLOGY & BIOENGINEERING, Issue 3 2005
Wan-Tzu Chen
Abstract Detection of the foodborne pathogen Listeria monocytogenes requires that food samples be processed to remove proteins and lipids, concentrate microorganisms to a detectable concentration, and recover the concentrated cells in a small volume compatible with micron-scale biochips. Mechanistic considerations addressed in this research include the roles of membrane structure, pore size, and detergents in maximizing recovery of cells from a complex biological fluid. The fluid in this case was a food sample (hotdog extract) inoculated with L. monocytogenes. This study showed how membrane filtration using a syringe filter is able to concentrate L. monocytogenes by 95× with up to 95% recovery of living microorganisms by concentrating 50 mL of food sample into a volume of 500 ,L. Tween 20 was added to the sample to prevent irreversible adsorption of the microorganism to the membrane and thereby help to ensure high recovery. Comparison of polycarbonate, mixed cellulose, nylon, and PVDF membranes with 0.2 to 0.45 ,m pores showed the 0.2 ,m polycarbonate membrane with straight through, mono-radial pores gives the highest recovery of living microorganisms. The mixed cellulose, nylon, and PVDF membranes have a fibrous structure whose characteristic openings are much larger than their effective pore size cut-offs of 0.22 or 0.45 ,m. We define conditions for rapid membrane-based cell concentration and recovery that has the potential to supplant enrichment steps that require a day or more. This approach has the added benefit of facilitating examination of a large amount of fluid volume by reducing its volume to a range that is compatible with the microliter scales of biochip or other biosensor detection systems. © 2004 Wiley Periodicals, Inc. [source]


Voltametric and Flow Injection Determination of Oxytetracycline Residues in Food Samples Using Carbon Fiber Microelectrodes

ELECTROANALYSIS, Issue 7 2003
L. Agüí
Abstract A voltammetric method for the determination of the antibiotic oxytetracycline (OTC) in food samples is reported. Carbon fiber microelectrodes (CFMEs), which allow voltammetric measurements to be performed in a small volume (1,mL) of the analyte extract from the samples, are employed. Repeatable electroanalytical responses were obtained with no need of applying cleaning treatments to the CFME. Under the optimized square-wave conditions, a linear calibration plot for OTC was obtained in the 1.0×10,6,1.0×10,4,mol,L,1 range, with a detection limit of 2.9×10,7,mol,L,1 (150,ng,mL,1) OTC. The determination of OTC by a flow-injection method with amperometric detection using a homemade flow cell specially designed to work with CFMEs, was also evaluated using pure acetonitrile as the carrier. The SW voltammetric method was applied to the determination of OTC in spiked milk and eggs samples, at 100,ng,mL,1 and 200,ng g,1 levels, respectively. The procedure involved the extraction of the analyte in ethyl acetate, evaporation of the solvent and reconstitution of the residue in acetonitrile ,5.0×10,4,mol,L,1 tetrabutylammonium perchlorate medium. Recoveries of 96±8 and 91±8% were obtained for milk and eggs, respectively, by applying the standard additions method. [source]


Cover Picture: Electrophoresis 15/2008

ELECTROPHORESIS, Issue 15 2008
Article first published online: 24 JUL 200
Regular issues provide a wide range of research and review articles covering all aspects of electrophoresis. Here you will find cutting-edge articles on methods and theory, instrumentation, nucleic acids, CE and CEC, miniaturization and microfluidics, proteomics and two-dimensional electrophoresis. Selected topics of issue 15 are: The application of perfluorooctanoate to investigate trimerization of the human immunodeficiency virus-1 gp41 ectodomain by electrophoresis Metabolic fingerprinting of schistosoma mansoni infection in mice urine with capillary electrophoresis Supercritical fluid extraction as an on-line clean-up technique for determination of riboflavin vitamins in food samples by capillary electrophoresis with fluorimetric detection A two-step electro-dialysis method for DNA purification from polluted metallic environmental samples. [source]


Heteroduplex mobility assay for the identification of Listeria sp. and Listeria monocytogenes strains: application to characterisation of strains from sludge and food samples

FEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 3 2003
N Garrec
Abstract One hundred and ten Listeria sp. isolates from sewage sludge were identified according to phenotypic and genotypic methods. The Listeria sp. strains isolated from five types of sludge from three sewage treatment plants in Angers (France) and the surrounding area included L. monocytogenes (55.5%), L. innocua (29.1%), L. seeligeri (13.6%) and L. welshimeri (1.8%). The majority of L. monocytogenes strains belonged to serotypes 4b, 1/2b and 1/2a. Moreover, a heteroduplex mobility assay based on the 16S rRNA sequences was tested for its ability to identify the six species of the genus Listeria. This study, performed on 283 Listeria sp. strains from human, food and sewage sludge samples, showed that all the species were distinguishable from one another. L. innocua and L. seeligeri showed respectively three and two distinct banding patterns. Within L. monocytogenes, four groups (I,IV) were defined. The majority of food and environmental isolates were clustered in group I and it is noteworthy that group IV clustered epidemiologic isolates and strains belonging to serotypes 4b, 1/2a and 1/2b. [source]


Detection of potentially enterotoxigenic food-related Bacillus cereus by PCR analysis

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 6 2010
Elisabetta Bonerba
Summary This study provides data on the prevalence of potentially pathogenic Bacillus cereus in foods from catering kitchens by evaluating the occurrence of B. cereus and the presence of virulence-associated genes. B. cereus was detected in 72/250 (28.8%) food samples. Specifically, B. cereus was highlighted in 34/74 (45.9%) pastries, 16/40 (40%) rice samples, 4/38 (10.5%) potato meals, 6/54 (11.1%) mozzarella samples and 12/44 (27.3%) meat meals. PCRs aimed at the hbl (C, D, A, B), nhe (A, B, C), bceT and cytK genes demonstrated a widespread distribution of the toxin-encoding genes among B. cereus isolates. The results highlight the frequent failure of control measures in catering kitchens and the need for intensive and continuous monitoring in order to assess the human health risk, as proposed by Regulation (EC) no. 1441/2007 on microbiological criteria for foodstuffs. [source]


Cooking DNA: the effect of ,domestic' cooking methods on detection of GM potato

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 12 2008
Loraine Van Der Colff
Summary The ability to detect GM material in otherwise unprocessed foods cooked using domestic methods is important should ,ready-to-eat' foods require labelling. This study addresses the issue of DNA degradation in foods as a result of cooking. A number of ,domestic' cooking methods were shown to affect the length of DNA sequences able to be PCR amplified from potato samples and the degree of degradation was treatment-specific. However, a. real-time PCR assay was developed and. GM material was positively identified in all cooked GM potato samples. This confirms that GM material should be able to be detected in otherwise unprocessed food samples cooked using domestic methods, even if the cooking process has partially degraded the DNA. Results indicate, however, that there may be implications of the cooking process on the ability to accurately quantify GM content in some cooked samples. [source]


Fluorescence polarization immunoassay based on a monoclonal antibody for the detection of ochratoxin A

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 8 2004
Won-Bo Shim
Summary A fluorescence polarization immunoassay (FPIA) based on a monoclonal antibody for the determination of ochratoxin A (OTA) was developed. Fluorescein-labelled OTA derivative (tracer) was synthesized and purified by thin-layer chromatography. The optimized OTA FPIA had a dynamic range from 5 to 200 ng mL,1 with IC50 value of 30 ng mL,1 and a detection limit of 3 ng mL,1. The method developed was characterized by high specificity and reproducibility. Cross-reactivity with other mycotoxins (zearalenone, aflatoxins, patulin and T-2 toxin) was negligible (<0.1%). Methanol extracts of barley samples were used for the analysis. The results of OTA determination in barley were compared with those determined by indirect competitive enzyme-linked immunosorbent assay (ELISA). Recoveries for the samples spiked at 50, 100 and 500 ng g,1 levels were 91, 90 and 97%, respectively, for FPIA, and 98, 98 and 102%, for ELISA. Naturally contaminated barley samples were analysed by these methods but some disagreement was observed between the results. The FPIA method can be applied for screening of food samples for OTA residues without a complicated clean-up. [source]


Comparison of three enrichment media for the isolation of Campylobacter spp. from foods

JOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2000
C.L. Baylis
Aim: This study compared the performance of three Campylobacter enrichment broths: Bolton broth (BB), Campylobacter Enrichment broth (CEB) and Preston broth (PB). Methods and Results: Pure cultures of target and competitor organisms, and naturally-contaminated food samples, were used to establish the performance of these media. In pure culture the PB supported the growth of the greatest number of strains of Campylobacter spp. but failed to inhibit some competitor organisms. The CEB showed the opposite result, inhibiting all 15 competitor organisms used but failing to support the growth of five Campylobacter strains. By comparison, BB showed the best compromise between inhibition of competitors and growth of Campylobacter. Conclusions: Plates inoculated with BB and CEB food enrichments resulted in more Campylobacter growth than those inoculated with PB, which supported significantly less typical growth (P , 0·001). The most common competitor organism isolated from PB was Escherichia coli, and Pseudomonas spp. were frequently isolated from BB and CEB. Both BB and CEB were better than PB for the isolation of Campylobacter from naturally-contaminated foods, although BB yielded more confirmed Campylobacter growth than CEB. Significance and Impact of the Study: This study highlighted differences in performance of media used to isolate Campylobacter spp. from foods. [source]


DETECTION OF SALMONELLA TYPHIMURIUM IN OYSTERS BY PCR AND MOLECULAR HYBRIDIZATION

JOURNAL OF FOOD QUALITY, Issue 5 2006
A.A. CORRÊA
ABSTRACT Because shellfish (oysters, clams and mussels) are filter feeders, i.e., able to concentrate pathogens from the surrounding waters within their tissues, they have been widely associated with outbreaks illness. The incidence of salmonellosis caused by the consumption of raw or undercooked shellfish, is a primary concern of public health agencies. Then, in recent years, more rapid and specific methods based on the DNA sequence of salmonella genes have been developed to detect low levels of pathogens in environmental and food samples. In this study, we developed a sensitive method to detect low levels of Salmonella typhimurium in oyster tissues (0.1 cfu/g). This methodology consisted of dissection of the gastrointestinal oyster tract, pre-enrichment of the samples in nonselective medium, DNA extraction and polymerase chain reaction followed by molecular hybridization using a digoxygenin-labeled amplicon-derived probe. These results can benefit the public health agencies and shellfish producers concerning microbiological and quality aspects of the commercial oyster production. [source]


A NOVEL MULTIPLEX POLYMERASE CHAIN REACTION FOR SIMULTANEOUS DETECTION OF YERSINIA ENTEROCOLITICA, STAPHYLOCOCCUS AUREUS, AEROMONAS AND SALMONELLA FROM CHICKEN MEAT AND MILK SAMPLES

JOURNAL OF FOOD SAFETY, Issue 2 2010
K. BALAKRISHNA
ABSTRACT Yersinia enterocolitica, Staphylococcus aureus, Aeromonas and Salmonella are among the most important foodborne bacterial pathogens. The majority of human infections caused by all of these organisms are associated with ingestion of undercooked and contaminated meat, dairy products and water where in the secreted bacterial toxins lead to foodborne intoxications. We, here, report a new multiplex polymerase chain reaction (mPCR) assay for the simultaneous detection of these important foodborne bacterial pathogens. The mPCR targeted Ail and virF genes of Y. enterocolitica, nuc and entB genes of S. aureus, aerA and 16S rRNA genes of Aeromonas and invA, an invasion protein A gene of Salmonella. An internal amplification control designed to check the false negative reactions in mPCR was also included. This procedure could detect initial populations of 1,100 cfu/g or /mL within 24 h in experimentally spiked food and water samples. When evaluated on a total of 104 naturally occurring food samples, the mPCR detected two samples to contain S. aureus, one was identified to contain Y. enterocolitica and four samples were identified to contain Salmonella species individually. This was compared with the standard microbiological and biochemical identification procedures. PRACTICAL APPLICATIONS All the microorganisms selected in this study are food and waterborne and contaminate a variety of food items. Pathogenic Y. enterocolitica and Aeromonas species are able to grow and multiply and secrete toxins even at low temperatures. The high throughput and cost-effective multiplex polymerase chain reaction method reported here could be a viable alternative for detection of pathogenic Y. enterocolitica, S. aureus, Aeromonas and Salmonella from food and environmental samples. [source]


IMPROVED MEDIUM FOR DETECTION OF KLEBSIELLA IN POWDERED MILK

JOURNAL OF FOOD SAFETY, Issue 1 2010
HONG GAO
ABSTRACT The selectivities to pathogenic Klebsiella strains of different isolation media were compared by known standard strains. The modified MacConkey-inositol-carbenicillin (MCIC) medium (Named MCIAC, MacConkey-inositol-adonitol-carbenicillin) supplemented with adonitol gave no false-negative colonies, and exhibited higher selectivity. MCIC and Simmons citrate agar with inositol (SCAI) media gave two false-negative colonies, respectively. These three media all gave two false-positive colonies, respectively. Salmonella Shigella medium gave four false-negative colonies and five false-positive colonies. Violet red bile glucose agar medium gave the most false-positive colonies, although it gave no false-negative colonies. One hundred samples of powdered milk were examined by MCIAC, MCIC and SCAI plates. The typical positive colonies were further identified using Vitek GNI Auto Microbic system and API 20E system. The results showed that the specificity of the MCIAC medium was higher than MCIC and SCAI media. PRACTICAL APPLICATIONS MacConkey-inositol-carbenicillin (MCIC) is the most commonly used selective medium for the detection of Klebsiella. But some inositol-nonfermenting Klebsiella strains would be missed when selected by this medium. We improved the MCIC medium by supplementing with 1% adonitol. The new modified medium (MacConkey-inositol-adonitol-carbenicillin, MCIAC) had advantages over other selective Klebsiella media in having a higher selectivity and an incubation time of only 16,24 h. MCIAC could be routinely used for pathogenic Klebsiella selection of powdered milk and other food samples. [source]


PREVALENCE AND ANTIMICROBIAL RESISTANCE OF LISTERIA SPECIES IN FOOD PRODUCTS IN BANGKOK, THAILAND

JOURNAL OF FOOD SAFETY, Issue 1 2010
SIRIPORN STONSAOVAPAK
ABSTRACT A total of 380 meat and meat products, dairy and dairy products, fresh vegetables, fresh seafood, and ready-to-eat food samples from supermarkets in Bangkok, Thailand were collected and analyzed for the occurrence of Listeria spp. and of Listeria monocytogenes. The overall incidence of Listeria spp. was 16.8%, most of them were isolated from raw meat and vegetables. L. monocytogenes was isolated from 18 (4.7%) out of 380 studied samples. Other species isolated were L. innocua (6.6%), L. ivanovii (0.8%), L. seeligeri (0.5%), L. grayi (1.6%) and L. welshimeri (2.6%). The antimicrobial susceptibilities of the 64 isolate of Listeria spp. were also examined by the standard disk diffusion method. Listeria spp. were resistant to penicillin (6.3%), chloramphenicol (3.1%) and tetracycline (1.6%), but sensitive to amoxicillin, vancomycin, ampicillin, rifampicin and sulfamethoxazole. PRACTICAL APPLICATIONS Listeria monocytogenes prevalence in food products in Bangkok has been documented. More studies on the occurrence of L. monocytogenes are needed to establish microbiological criteria of foods in the country. The findings of our study, increases in antibiotic resistance among Listeria spp. will provide useful information for the development of public health policy in the use of antimicrobials in food animal production. [source]


SIMULTANEOUS DETECTION OF LISTERIA MONOCYTOGENES, STAPHYLOCOCCUS AUREUS, SALMONELLA ENTERICA AND ESCHERICHIA COLI O157:H7 IN FOOD SAMPLES USING MULTIPLEX PCR METHOD

JOURNAL OF FOOD SAFETY, Issue 3 2009
D. ZHANG
ABSTRACT In this study, one multiplex polymerase chain reaction (MPCR) assay was developed for simultaneous detection of four foodborne pathogens, i.e., Listeria monocytogenes, Staphylococcus aureus, Salmonella enterica and Escherichia coli O157:H7. Five specific primer pairs were designed based on the nucleotide sequences of hemolysin gene (hly) of Listeria monocytogenes, thermostable nuclease gene (nuc) of Staphylococcus aureus, invasion gene (invA) of Salmonella enterica, shiga-like toxin gene (stx) and intimin gene (eae) of Escherichia coli O157:H7 in this assay. The specificity and sensitivity of the MPCR method were validated, and the limit of detection (LOD) of this method was about 10 copies. One cfu/mL each of these foodborne pathogens spiked in practical food samples, i.e., ground meat, beef, pork, fish, shrimp, cheese, canola leaf and cabbage, could be detected simultaneously after 24 h enrichment at a rate of 87.5%, indicating that the established MPCR detection method was effective and suitable for practical use. PRACTICAL APPLICATIONS This study presents a quick and effective identification method to simultaneous monitor four foodborne pathogens in food samples. The specificity and sensitivity of this method can be used to unambiguously identify these four foodborne pathogens in practical food samples based on the species-specific genes. Therefore, this detection method is applicable for surveillance measures of these four foodborne pathogens in the food production chain. [source]


Development of a Solid-Phase Extraction,Enzyme-Linked Immunosorbent Assay for the Determination of 17,-19-Nortestosterone Levels in Antifatigue Functional Foods

JOURNAL OF FOOD SCIENCE, Issue 8 2009
Yan Zhang
ABSTRACT:, 17,-19-nortestosterone (17,-NT) has been illegally used in antifatigue functional foods to promote muscle growth and improve endurance. A rapid and sensitive solid-phase extraction,enzyme-linked immunosorbent assay (SPE-ELISA) method was developed and successfully applied to analyze the levels of 17,-NT in antifatigue functional foods. A polyclonal antibody against 17,-NT was produced from rabbits immunized with the 17,-NT-BSA conjugate, and a competitive direct enzyme-linked immunosorbent assay was developed for the rapid detection of 17,-NT. The concentration causing 50% inhibition (IC50) and the limit of detection (LOD) were found to be 0.08 and 0.0055 ng/mL, respectively; this was better than methods previously reported that had a LOD of 2.4 ng/mL. C18 cartridges were investigated for use in removing the effects of matrix in foods, and the sample purification protocol was optimized. Using the developed SPE-ELISA method, recoveries of functional food samples were obtained in the range of 71% to 91.5%. Moreover, 2 kinds of antifatigue functional foods were analyzed using the established ELISA and HPLC methods. The correlation coefficient of the results obtained using the 2 methods was greater than 0.98. Thus, the preliminary evaluation of the SPE-ELISA method proved that it is a specific, sensitive, and precise tool that can be used for the practical detection of 17,-NT in various antifatigue functional food samples. [source]


Trans Fatty Acid Content of Selected Foods in an African-American Community

JOURNAL OF FOOD SCIENCE, Issue 6 2006
Z. Huang
ABSTRACT:,Trans fatty acid content was examined in several grocery foods and fast foods in an African-American community. Food samples were selected based on the frequency of use among this population group in the local community. Samples were collected 3 times with an interval of 1 wk. Total fat content was analyzed by Soxhlet method. Fatty acids profile, including trans fatty acids, was analyzed by GC,MS. In grocery foods, no trans fatty acids were detected in fish sticks, salad dressing, mayonnaise, muffin, and potato chips. Margarine contained the highest trans fatty acid at a level of 19.13%. The trans fatty acid level in crackers, cookies, butter, chicken patties, and biscuits mix ranged from 0.51% to 1.77%. In fast foods, no trans fat was detected in dressing. All the fried food and bakery food sampled in this study contain trans fat. The level varied from 2.07% to 10.30%. The principal trans fatty acid was trans 18:1. Other trans fatty acids found were trans 18:2, trans 19:1, and trans 16:1. In a total of 23 food samples, 16 of them were found to contain trans fatty acid. The results demonstrated that trans fat is commonly found in foods of the African-American community. The trans fatty acids content in tested samples varied from 0% to 19.13%. [source]


Using a Motion-Capture System to Record Dynamic Articulation for Application in CAD/CAM Software

JOURNAL OF PROSTHODONTICS, Issue 8 2009
Oliver Röhrle PhD
Abstract Purpose: One of the current limitations of computer software programs for the virtual articulation of the opposing teeth is the static nature of the intercuspal position. Currently, software programs cannot identify eccentric occlusal contacts during masticatory cyclic movements of the mandible. Materials and Methods: Chewing trajectories with six degrees of freedom (DOF) were recorded and imposed on a computer model of one subject's maxillary and mandibular teeth. The computer model was generated from a set of high-resolution ,-CT images. To obtain natural chewing trajectories with six DOF, an optoelectronic motion-capturing system (VICON MX) was used. For this purpose, a special mandibular motion-tracking appliance was developed for this subject. Results: Mandibular movements while chewing elastic and plastic food samples were recorded and reproduced with the computer model. Examples of mandibular movements at intraoral points are presented for elastic and plastic food samples. The potential of such a kinematic computer model to analyze the dynamic nature of an occlusion was demonstrated by investigating the interaction of the second molars and the direction of the biting force during a chewing cycle. Conclusions: The article described a methodology that measured mandibular movements during mastication for one subject. This produced kinematic input to 3D computer modeling for the production of a virtual dynamic articulation that is suitable for incorporation into dental CAD/CAM software. [source]


PREFERENCE FOR ONE OF TWO IDENTICAL STIMULI: EXPECTATIONS, EXPLICIT INSTRUCTIONS AND PERSONAL TRAITS

JOURNAL OF SENSORY STUDIES, Issue 2010
KATHRYN W. CHAPMAN
ABSTRACT Most consumers, given two identical food samples, express a preference for one, rather than choosing a no-preference option. The stability and potential causes of this seemingly irrational preference were examined across three trials under different conditions, specifically, when the first test pair was identical or different, and when participants were explicitly told that the pairs would often be identical. Choice of no preference typically increased from the first to second trial, especially for groups who saw a pair of different samples on the first trial. The explicit instruction that samples might be the same failed to reduce expressing a preference on the initial trial although it had some effect on later trials. Analysis, by individuals, of sequences of preference or no-preference responses across trials support independence of sequential responses and argue against stable personal traits as a predictor of preference choice. PRACTICAL APPLICATIONS More research needs to be done to understand the origins and operation of biases in preference tests. When tested under conditions in which the samples differ only slightly, participants tend to avoid the no-preference option. This is potentially important when interpreting the results of preference tests and assigning practical significance to their outcomes. Also, single trial testing may produce somewhat different results from multi-trial testing, the latter allowing for examination of effects of variation in recent experience. [source]


Determination of banned Sudan dyes in food samples by molecularly imprinted solid phase extraction-high performance liquid chromatography

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 19 2009
Claudio Baggiani
Abstract A method for molecularly imprinted SPE of banned Sudan azo-dyes from food samples was investigated. The molecularly imprinted polymer was obtained by suspension polymerization using 1-(4-chlorophenyl)azonaphthalen-2-ol as the mimic template. The molecular recognition properties of imprinted beads were evaluated for use as a SPE sorbent, in order to develop a selective extraction protocol for the Sudan class of dyes. The optimized extraction protocol resulted in a reliable molecularly imprinted SPE (MISPE) method suitable for HPLC analysis. It was selective for the main analyte, Sudan I, and the related azo-dyes Sudan II, III, IV, Sudan Red B, and Sudan Red 7B, while the permitted azo-dyes Allura Red AC, Neococcin, and Sunset Yellow FCF were not extracted. The method was tested for Sudan I, II, III, and IV in five different food samples (hot chilli pepper, hot chilli tomato sauce, sausage, tomato sauce, and hard boiled egg yolk) at three concentration levels (15, 100, and 300 ,g/g). It demonstrated itself to be insensitive to the presence of different complex matrices, precise, accurate, and with good recovery rates (85,101%). The LOD and LOQ were satisfactory for most analytical determinations. [source]


PREDICTING SENSORY COHESIVENESS, HARDNESS AND SPRINGINESS OF SOLID FOODS FROM INSTRUMENTAL MEASUREMENTS

JOURNAL OF TEXTURE STUDIES, Issue 2 2008
R. DI MONACO
ABSTRACT The sensory evaluation of cohesiveness, hardness and springiness of 15 solid food samples was performed by eight trained assessors. The rheologic response of the 15 samples was estimated by performing cyclic compression tests and stress,relaxation tests. From the force,deformation curves of the first two cycles of the compression test, texture profile analysis parameters related to cohesiveness, hardness and springiness were calculated. Young's modulus (E), strain (di) and stress (si) at peak as well as irrecoverable strain (ri) and irrecoverable work (Li) were monitored during the first five cycles. From the stress,relaxation response, Peleg's linearization model parameters, K1 and K2, were estimated by best-fit regression. These parameters were used for predicting sensory attributes. Hardness and springiness were both accurately predicted by rheologic properties, while cohesiveness prediction was less representative. PRACTICAL APPLICATIONS This study contributes to enhance the knowledge in the research area of sensory instrumental correlation. Also, the research allows to better understanding that no single instrument is able to measure all texture attributes adequately. In fact, the results demonstrate that both stress,relaxation and cyclic compression tests need to be performed for the correct prediction of sensory responses. [source]


THE ANALYSIS OF STRESS RELAXATION DATA OF SOME VISCOELASTIC FOODS USING A TEXTURE ANALYZER,

JOURNAL OF TEXTURE STUDIES, Issue 4 2006
H. SINGH
ABSTRACT Uniaxial compression test for dough and several commercial products like jello, mozzarella cheese, cheddar cheese, tofu and sausage (cooked and uncooked) was performed using a texture analyzer (TA). Percent stress relaxation (%SR ), k1 (initial rate of relaxation), k2 (extent of relaxation) and relaxation time (RT) were calculated and compared for different products. The TA software was used to convert the raw SR data into a linear form. Constants k1 and k2 were determined from the intercept and slope of the linear data. Higher values of %SR and k2 (90 and 9, respectively) indicated higher elasticity for jello, whereas wheat flour dough samples showed the lowest values (20,30) for %SR and 1 to 2 for k2. The RT and k1 values were not good indicators for differentiating different products based on their viscoelastic behavior. Measurement of RT was limited by the maximum time for which the data were collected, whereas k1, because of its mathematical form, needed careful interpretation. In this study, %SR was found to be a good measure to interpret viscoelasticity of different food samples. [source]


Using unlabelled data to update classification rules with applications in food authenticity studies

JOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES C (APPLIED STATISTICS), Issue 1 2006
Nema Dean
Summary., An authentic food is one that is what it purports to be. Food processors and consumers need to be assured that, when they pay for a specific product or ingredient, they are receiving exactly what they pay for. Classification methods are an important tool in food authenticity studies where they are used to assign food samples of unknown type to known types. A classification method is developed where the classification rule is estimated by using both the labelled and the unlabelled data, in contrast with many classical methods which use only the labelled data for estimation. This methodology models the data as arising from a Gaussian mixture model with parsimonious covariance structure, as is done in model-based clustering. A missing data formulation of the mixture model is used and the models are fitted by using the EM and classification EM algorithms. The methods are applied to the analysis of spectra of food-stuffs recorded over the visible and near infra-red wavelength range in food authenticity studies. A comparison of the performance of model-based discriminant analysis and the method of classification proposed is given. The classification method proposed is shown to yield very good misclassification rates. The correct classification rate was observed to be as much as 15% higher than the correct classification rate for model-based discriminant analysis. [source]