scholarly journals Rapid Determination of Listeria monocytogenes by Automated Enzyme-Linked Immunoassay and Nonradioactive DNA Probe

2000 ◽  
Vol 83 (1) ◽  
pp. 86-88 ◽  
Author(s):  
Khalil F Kerdahi ◽  
Philip F Istafanos
Keyword(s):  
Listeria Monocytogenes ◽  
Rapid Determination ◽  
Food Samples ◽  
Dna Probe ◽  
Negative Results ◽  
Smoked Salmon ◽  
Colony Forming Units ◽  
Low Levels ◽  
Analytical Time

Abstract A rapid and reliable analytical method was developed to detect and confirm the presence of Listeria monocytogenes in raw and partially processed foods. Forty-nine food samples (25 mixed cut vegetable salad, 12 smoked salmon, and 12 sterile smoked salmon) were individually inoculated with high levels [10–100 colony forming units (cfu)/25 g sample] and low levels (1–10 cfu/25 g sample) of L. monocytogenes, and were screened using the Vitek Immuno Diagnostic Assay (VIDAS) Listeria monocytogenes (VIDAS LMO)]. Positive test results were confirmed as L. monocytogenes by nonradioactive DNA probe. All samples inoculated with high levels of L. monocytogenes were detected by VIDAS and 96% were confirmed as L. monocytogenes by DNA probe. VIDAS LMO detected 89% of samples inoculated with low levels of L. monocytogenes, and 87% of these were confirmed as positive by DNA probe. In addition, 12 other samples (4 from each of mixed cut vegetable salad, smoked salmon, and sterile smoked salmon) were inoculated with high levels of L. ivanovii, L. seeligeri, L. welshimeri, L. innocua, L. grayi, and L. murrayi. Samples were assayed by the same protocol and all gave negative results. Compared with the cultural method, the VIDAS LMO nonradioactive DNA probe combination is highly specific, discriminates between L. monocytogenes and all other Listeria species, and reduces analytical time.

Microbiological Quality of Commercial Tofu

1984 ◽  
Vol 47 (3) ◽  
pp. 177-181 ◽  
Author(s):  
T. G. REHBERGER ◽  
L. A. WILSON ◽  
B. A. GLATZ
Keyword(s):  
Microbiological Quality ◽  
Plate Count ◽  
Microbial Counts ◽  
Colony Forming Units ◽  
Low Levels ◽  
Microbial Groups ◽  
Yeasts And Molds ◽  
Processing Techniques

A study was done to investigate the microbiological quality of commercial tofu available in local retail outlets. A sampling method was first developed to obtain accurate and representative microbial counts of individual pieces of tofu. Plate count determination of total aerobic organisms, psychrotrophs, coliforms, sporeformers, yeasts and molds, and staphylococci were made on 60 tofu samples (representing three lots each of four different brands) obtained within 24 h after delivery to the retail store. In addition, for two brands that provided manufacturer's pull dates, the same microbial counts were obtained for samples stored in the laboratory at 10°C until the pull date. Of the tofu sampled immediately after purchase, 83% of the lots tested had total counts greater than 106 colony-forming units (CFU)/g and psychrotrophic counts greater than 104 CFU/g. In addition, 67% of the lots tested had confirmed coliform counts greater than 103 CFU/g. Very low levels (less than 10 CFU/g) of all other microbial groups tested for were found in the majority of lots. Samples held until the manufacturer's pull date contained higher total and psychrotrophic counts but lower or stable counts of other organisms compared with samples tested immediately after purchase. To improve the microbiological quality of tofu, processors need to reduce initial loads by improving sanitation and processing techniques, and retailers should provide more consistent and colder refrigerated storage.

scholarly journals Growth Potential of Listeria monocytogenes in Three Different Salmon Products

Foods ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 1048 ◽  
Author(s):  
Corinne Eicher ◽  
Andres Ruiz Subira ◽  
Sabrina Corti ◽  
Arnulf Meusburger ◽  
Roger Stephan ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Challenge Test ◽  
High Growth ◽  
Growth Potential ◽  
High Concentration ◽  
Food Borne ◽  
Smoked Salmon ◽  
Good Manufacturing Practices ◽  
Challenge Tests ◽  
Low Levels

Cold smoked salmon and sushi salmon have been implicated in outbreaks of listeriosis. We performed challenge tests and a durability study with Listeria monocytogenes on different salmon products to determine the growth potential of this important food-borne pathogen. Data from the challenge test showed a significant growth potential of L. monocytogenes on all of the tested salmon products, with faster growth in sushi salmon than in cold smoked salmon. In identical products that were naturally contaminated at low levels, the durability study did not confirm a high growth potential, possibly due to interactions with competing microflora. The injection of sodium lactate (NaL) at a high concentration (30%) into cold smoked salmon significantly reduced the growth potential of L. monocytogenes. In addition to good manufacturing practices, the injection of higher concentrations of NaL may therefore be a useful additional hurdle to prevent growth of L. monocytogenes to high numbers in the tested salmon products.

scholarly journals Rapid determination of actinides in emergency food samples

2011 ◽  
Vol 292 (1) ◽  
pp. 339-347 ◽  
Author(s):  
Sherrod L. Maxwell ◽  
Brian K. Culligan ◽  
Angel Kelsey-Wall ◽  
Patrick J. Shaw
Keyword(s):  
Rapid Determination ◽  
Food Samples

scholarly journals A new method for rapid detection of Listeria monocytogenes in food

2000 ◽  
Vol 18 (No. 3) ◽  
pp. 103-109 ◽  
Author(s):  
K. Zdeňková ◽  
K. Demnerová ◽  
G. Jeníková ◽  
J. Pazlarová
Keyword(s):  
Listeria Monocytogenes ◽  
Pcr Primers ◽  
Immunomagnetic Separation ◽  
Food Samples ◽  
Special Importance ◽  
Ground Meat ◽  
Specific Detection ◽  
Gene Encoding ◽  
Pcr Method

Listeria monocytogenes represents serious danger for human health. Thus detection of this pathogen in food, which represents its main means of entry into the organism, is a topic of special importance. The original classic methods for the determination of Listeria monocytogenes are in general laborious and time-consuming procedures. In order to address this issue we developed a new rapid method for specific detection of Listeria monocytogenes in food samples. The method consists of three steps: i) enrichment of food microflora (16 h), ii) selective isolation of Listeria sp. exploiting immunomagnetic separation (2–3 h) followed by iii) precise identification of Listeria sp. and Listeria monocytogenes using duplex PCR. PCR primers specific to part of 16S rRNA were used in order to identify the members of Listeria genus. The specific identification of Listeria monocytogenes was accomplished exploiting a pair of primers specific to gene encoding invasion-associated protein – iap (4–5 h). Amplification products, 1003 bp and 593 bp respectively, were separated by electrophoresis and visualized by UV detection. The optimized IMS-PCR method was used to test the presence of Listeria sp. and Listeria monocytogenes in food samples (ground meat, low-fat milk and cheese [olomoucké tvarůžky]). A comparison of the efficiency of the bacteria enrichment step by IMS and centrifugation was also performed. The analysis time including enrichment is less than 24 h. The detection limit for Listeria monocytogenes was found between 101–102 cfu per 25 g of food sample.

Threshold Radioactivity for Bulk Food Samples by Gamma Spectroscopy

1965 ◽  
Vol 48 (1) ◽  
pp. 1-5
Author(s):  
Harry M Yakabe ◽  
Hiram Neilson
Keyword(s):  
Gamma Ray ◽  
Gamma Spectroscopy ◽  
Rapid Determination ◽  
Detection System ◽  
Fission Products ◽  
Food Samples ◽  
Family Of Curves ◽  
Lower Limits ◽  
True Activity

Abstract In the surveillance of bulk food produce by gamma ray spectroscopy for fission products, the activities of the commonly observed radionuclides are frequently in the magnitude of background inherent to the detection system. The problems of determining whether the sample is in fact contaminated, the lower limits of detecting the radionuclides, and the effect of compton smear on the lower limits are discussed. The discussions are based on the modified spectrum stripping method for quantitative analysis of gamma ray spectrum for the following radioisotopes: Cs-137, Zr-95/Nb-95, and K-40. A family of curves are shown for rapid determination of the minimum detectable true activity (AII) of Cs-137.

Novel Cd(II) Ion Imprinted Polymer Coated on Multiwall Carbon Nanotubes as a Highly Selective Sorbent for Cadmium Determination in Food Samples

2014 ◽  
Vol 97 (1) ◽  
pp. 173-178 ◽  
Author(s):  
Forouzan Aboufazeli ◽  
Hamid Reza Lotfi Zadeh Zhad ◽  
Omid Sadeghi ◽  
Mohammad Karimi ◽  
Ezzatollah Najafi
Keyword(s):  
Carbon Nanotubes ◽  
Multiwall Carbon Nanotubes ◽  
Food Samples ◽  
Standard Reference Materials ◽  
Ion Imprinted Polymer ◽  
Imprinted Polymer ◽  
Ion Imprinted ◽  
Low Levels ◽  
Multiwall Carbon

Abstract The application of a novel Cd(II) ion imprinted polymer coated on multiwall carbon nanotubes was investigated for preconcentration and determination of low levels of Cd ions. This novel sorbentwas characterized by scanning electron microscopy, thermal gravimetric/differential thermal analysis, elemental analysis, and FTIR spectrometry. Effects of various factors, such as pH of the sample solution, eluent (type, concentration, and volume), and flow rates of the sample and eluent, were evaluated in this study. To investigate the selectivity of the sorbent toward Cd(II) ions, the effects of a variety of ions on preconcentration and recovery of Cd(II) ions were investigated. TheLOD was 1.3 ng/mL; the recovery and RSD of the method were 96.4% and below 3.1%, respectively. Validation of the method was performed by analyzing some standard reference materials with certified Cd(II) concentrations. Finally, the sorbent was applied for separation and determination of Cd(II)ions in food samples.

First report on a BODIPY-based fluorescent probe for sensitive detection of oxytetracycline: application for the rapid determination of oxytetracycline in milk, honey and pork

RSC Advances ◽  
2016 ◽  
Vol 6 (92) ◽  
pp. 89288-89297 ◽  
Author(s):  
Zhiqun Xu ◽  
Xiaofeng Yi ◽  
Qiao Wu ◽  
Yincan Zhu ◽  
Minrui Ou ◽  
...  
Keyword(s):  
Fluorescent Probe ◽  
Rapid Determination ◽  
Food Samples ◽  
Sensitive Detection ◽  
Effective Solution ◽  
First Report

An effective solution for oxytetracycline detection in actual food samples by a novel BODIPY-based fluorescent probe.

Examination of Listeria monocytogenes in Seafood Processing Facilities and Smoked Salmon in the Republic of Ireland

2015 ◽  
Vol 78 (12) ◽  
pp. 2184-2190 ◽  
Author(s):  
DARA LEONG ◽  
AVELINO ALVAREZ-ORDÓÑEZ ◽  
SARAH ZAOUALI ◽  
KIERAN JORDAN
Keyword(s):  
Listeria Monocytogenes ◽  
Gel Electrophoresis ◽  
Benzalkonium Chloride ◽  
Food Samples ◽  
Pulsed Field Gel Electrophoresis ◽  
Pulsed Field ◽  
Republic Of Ireland ◽  
Smoked Salmon ◽  
The Republic ◽  
Seafood Processing

Listeria monocytogenes is a foodborne pathogen that causes listeriosis, a relatively rare but life-threatening disease primarily affecting immunocompromised individuals. The aim of this study was to determine the prevalence of L. monocytogenes in the seafood processing industry in the Republic of Ireland. The occurrence of L. monocytogenes was determined by regular sampling of both food samples and processing environment swabs at eight seafood processing facilities over two calendar years. All samples were analyzed by the International Organization for Standardization 11290-1 standard method, and the isolates were characterized by PCR, pulsed-field gel electrophoresis, serotyping, and the occurrence of some genes related to survival under stress (SSI-1, Tn6188, and bcrABC). A prevalence of 2.5% in 508 samples (433 environmental swabs and 75 food samples) was found. From the isolates obtained, eight different pulsed-field gel electrophoresis profiles were identified, two occurring in more than one facility and one occurring in food and the environment. Five of the eight pulsotypes identified contained at least one of the three stress survival–related genes tested. The tolerance of the isolates to benzalkonium chloride, a representative quaternary ammonium compound, was also examined and ranged from 5.5 ± 0.5 to 8.5 ± 0.5 ppm of benzalkonium chloride. To evaluate the ability of smoked salmon to support the growth of L. monocytogenes, including the T4 widespread pulsotype that was isolated, a challenge test was performed on cold-smoked salmon obtained from two separate producers. The results showed clearly that both types of smoked salmon supported the growth of L. monocytogenes. Although occurrence of L. monocytogenes on seafood was low, this study showed that the smoked salmon used in this study can support the growth of L. monocytogenes; therefore, vigilance is required in the processing facilities to reduce the associated risk.

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