Horizontal method for the detection and enumeration of Listeria monocytogenes and of Listeria spp. - Part 1: Detection method
Qualitative process control with CRM-LM
- Use a quantitative reference material (CRM-LM) with a known number of Listeria monocytogenes.
- Defrost the material at room temperature for 30 minutes.
- Mix well before use.
- In the case of qualitative operations the contamination level of the reference material (CRM-LM) must be representative of the limit of detection.
- At an average contamination level of 5 cfu per control sample, the probability of using a coincidentally uninfected (negative) sample according to the Poisson spread is less than 1%.
- Incubate at (37 ± 1) °C for (48 ± 4) h.
- Determine the absence or presence of the microorganism and register your finding in a qualitative control chart.
- The characteristic reaction is: Blue green colonies with opaque halo.
Single strain te be used for the detection of Listeria monocytogenes and of Listeria spp.
Process control detection method