Page 47 - FoodFocusThailand No.179 February 2021

STRONG QC & QA

medium containing unique dyes which indicate metabolic activity as
microorganisms grow. The system can detect a range of organisms
1
including total aerobic microbial count (TAMC), Rapid methods for
hygiene monitoring, total combined moulds and yeasts count (TCMY),
enterobacterial count (bile tolerant gram-negative bacteria),
Escherichia coli, coliforms, Pseudomonas aeruginosa, Staphylococcus
aureus, Salmonella, and lactic acid bacteria.
1.2 Impedance Microbiology
It is based on the measurement of changes in electrical impedance
of a culture medium or reaction solution resulting from bacterial
metabolism during growth. There are several analytical instruments
based on the impedance microbiology for food samples . The
2-4
systems are designed for environmental monitoring and can detect
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Enterobacteriaceae, coliform, E. coli, Salmonella, Listeria spp.,
coagulase positive Staphylococci, yeasts and moulds as well as total
viable count (TVC).
1.3 Colorimetric Detection of Carbon Dioxide Production
This technique measures carbon dioxide (CO ) produced as a
2
metabolite as microorganisms grow in a liquid medium. CO diffuses
2
and interacts with the liquid medium decreasing the pH and leading
to changes in colour of the medium. The kits/swabs are commercially
available . testing. Rapid microbial detections have many benefits, such as shorter
6-7
1.4 Chromogenic Culture Media detection times and less-skilled workers to operate the equipment than
They are developed to detect enzyme activity known to be specific the conventional method that supports manufacturers in making quicker
to the organism of interest. The media are produced in two formats decisions and solving a skilled labour shortage.
- broths and agars and available to detect a variety of microorganisms
in food and environmental samples, including Listeria spp.,
L. monocytogenes, Salmonella, coliforms, E. coli, Enterobacteriaceae,
Staphylococcus aureus, yeasts and mould as well as the TVC. There ข้้อมููลเพิ่่�มูเติ่มู/Additional Information
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is a range of companies that offer chromogenic culture media for 1 BioLumix and Soleris supplied by Neogen
2 Bactomater (bioMerieux)
microbial detection.
3 Rapid Automated Bacterial Impedance Technique (RABIT)
1.5 Phage Based Pathogen Detection
This method has been developed to detect pathogens using (Whitley Scientific Ltd.)
4 Malthus system (Malthus Instruments Ltd.)
bacteriophage or phage, which is highly specific to the bacterial 5 The BacTrac and μ-Trac systems from Sy-Lab
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species or subspecies. There are off the shelf phage-based detection 6 Proteus (CLEANPIX™ Test)
systems assays available for Salmonella and Listeria detection . 7 ECOLAB (Klerkit Sterikit)
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2. Rapid Indicator-Testing for Biomarkers 8 Salmonella and Listeria detection, VIDAS UP supplied by bioMerieux
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Rapid indicator-testing for biomarkers is mostly based on nucleic 9 BAX System X5 (Hygiena™)
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acid, including DNA and RNA. Real-time polymerase chain reaction 10 BAX System Q7 (DuPont Qualicon)
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(PCR) is one of the most commonly used. There are many 11 TaqMan™ (Applied Biosystems™)
commercially available real-time PCR systems for pathogen 12 MicroSeq (Applied Biosystems)
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detection 9-13 (Falowska, 2018); however, only selected assays are 13 foodproof (Biotecon Diagnostics)
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suitable for environmental monitoring. The assays for hygiene 14 Molecular Detection System (3M™)
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monitoring detect microorganisms such as Salmonella, 15 ANSR (Neogen)
L. monocytogenes and Enterobacter sakazakii. Moreover, 16 Loopamp detection kit (Eiken Chemical Company Ltd.)
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loop-mediated isothermal amplification (LAMP) of DNA and RNA have 17 ANSR Listeria Right Now™ supplied by Neogen
been developed to high sensitivity and fast results. These assays
enable the detection of pathogens from environmental samples such เอกสารอ้างอ่ง/References
as Salmonella, Listeria species, E. coli O157, Cronobacter or Falowska, A. 2018. Rapid methods for hygiene monitoring. White Paper.
Legionella 14-16 . For RNA detection by reverse-transcription LAMP Campden BRI, UK.
(rtLAMP), a commercially available rtLAMP assay has been Sogin J.H., G.L. Velasco, B.Yorden, C.K. Lingle, J.M. David, M. Cobo and
specifically designed for Listeria detection from environmental R.W. Worobo. 2020. Implementation of ATP and microbial indicator testing
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samples . for hygiene monitoring in a tofu production facility improves product
quality and hygienic conditions of food contact surfaces: A case study.
The verification should apply all aspects to achieve hygiene Appl Environ Microbiol. DOI: 10.1128/AEM.02278-20
monitoring, including visual inspection, ATP testing, and microbiological
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