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A selective medium for the rapid detection by an impedance technique of Pseudomonas spp. associated with poultry meat
G Salvat1, S Rudelle, F Humbert
1Centre National d'Etudes Vétérinaires et Alimentaires, CNEVA/Ploufragan, France.
Abstract:
A new medium for detecting and enumerating Pseudomonas spp. associated with poultry meat spoilage by a rapid impedance technique was developed, after testing potential growth promoters for eight Pseudomonas strains and inhibitors against eight competing strains (Enterobacteriaceae) able to grow on the medium of Mead and Adams (1977). Four basal media (brain heart infusion, brucella broth, Shaedler broth and Whitley impedance broth (WIB)) and a synthetic medium were evaluated. Whitley impedance broth was the best basal medium for detecting variations in impedance in relation to Pseudomonas growth. The efficiency of WIB was improved by adding compounds which enhanced the growth of Pseudomonas on the synthetic medium. Among the incubation temperatures tested, 22 degrees C proved to be the best compromise between growth of Pseudomonas associated with poultry meat spoilage and inhibition of competitors. Among the 15 inhibitory substances evaluated against Pseudomonas competitors, five were chosen for inclusion in the final medium: metronidazole, carbenicilline, cetrimide, cycloheximide and diamide (MCCCD medium). Preliminary results obtained from experiments with beef and pork meat showed that this medium could also be used without diamide and at an incubation temperature of 25 degrees C. The impedance technique using MCCCD medium was then compared with an official method which uses the medium of Mead and Adams (1977) on 106 samples of poultry neck skin. The linear regression coefficient between the two techniques was approximately r = 0.85. Impedance was able to detect 10(3) Pseudomonas g-1 within less than 19 h making it a promising technique for predicting poultry meat spoilage.
Insights
A new impedance technique using the MCCCD medium effectively detects Pseudomonas spp. in poultry meat, offering a rapid and reliable method for predicting spoilage. This method significantly reduces detection time compared to traditional approaches.
Area of Science:
- Food Microbiology
- Microbial Detection Techniques
- Food Safety
Background:
- Poultry meat spoilage is often caused by Pseudomonas species.
- Rapid and accurate detection methods are crucial for food safety and quality control.
- Existing methods for Pseudomonas enumeration can be time-consuming.
Purpose of the Study:
- To develop a novel impedance-based medium for rapid detection and enumeration of Pseudomonas spp. in poultry meat.
- To optimize the medium composition and incubation conditions for enhanced specificity and sensitivity.
- To compare the performance of the new technique with an official standard method.
Main Methods:
- Evaluation of four basal media and a synthetic medium for impedance variations related to Pseudomonas growth.
- Optimization of growth promoters and inhibitors, including metronidazole, carbenicilline, cetrimide, cycloheximide, and diamide (MCCCD medium).
- Testing of incubation temperatures and comparison with the Mead and Adams (1977) medium using poultry meat samples.
Main Results:
- Whitley impedance broth (WIB) was identified as the optimal basal medium.
- The MCCCD medium, incubated at 22°C, demonstrated effective growth of Pseudomonas while inhibiting competitors.
- The impedance technique using MCCCD medium showed a high correlation (r = 0.85) with the official method, detecting 10(3) Pseudomonas g-1 in under 19 hours.
Conclusions:
- The developed impedance technique with MCCCD medium is a promising, rapid, and reliable method for detecting Pseudomonas spp. in poultry meat.
- This technique can significantly reduce the time required for microbial analysis, aiding in the prediction of poultry meat spoilage.
- The method shows potential for application to other meat types and can be adapted for different incubation conditions.