AS 5013.24.1:2020 pdf free.Food microbiology Method 24.1: Microbiology of the food chain一. Horizontal method for the detection and enumeration of Listeria monocytogenes and of Listeria spp.一Detection method (ISO 11290-1:2017, MOD).
4.4 Plating out and identification
From the cultures obtained in 4.2 and 4.3, plating out on the two selective solid media:
— Agar Listeria according to Ottaviani and Agosti (see References [16] and [17] and B.3);
— any other solid selective medium at the choice of the laboratory complementary to Agar Listeria according to Ottaviani and Agosti, using a different substrate and/or principle than the one used in Listeria agar according to Ottaviani and Agosti (see B.4). See Annex E for information about media.
Incubation of the Agar Listeria according to Ottaviani and Agosti at 37 °C for a total of 48 h. If colonies of presumptive L. monocytogenes or Listeria spp. are evident at 24 h the incubation may be stopped at this stage. Incubation of the second selective medium at the appropriate temperature and examination after the appropriate time.
4.5 Confirmation
Subculturing of the colonies of presumptive L. monocytogenes or Listeria spp., plated out as described in 4.4, and confirmation by means of appropriate morphological and/or biochemical tests.
5 Culture media and reagents
For current laboratory practices, refer to ISO 11133.
Composition and performance testing of culture media and reagents and their preparation are described in Annex B.
6 Equipment and consumables
Usual microbiological equipment (as specified in Iso 7218) and, in particular, the following.
6.1 Apparatus for dry sterilization (oven) or wet sterilization (autoclave). As specified in ISO 7218.
6.2 Drying cabinet or incubator, capable of being maintained between 25 °C and 50 °C.
6.3 Incubators, capable of operating at 30 °C ± 1 °C, 37 °C ± 1 °C and at 25 °C ± 1 °C (optional).
6.4 Water bath, capable of operating at 47 °C to 50 °C.
6.5 Sterile loops approximately 3 mm in diameter or 10 iii, and inoculating needle or wire.
6.6 pH meter, capable of being read to the nearest 0,01 pH unit at 25 °C, enabling measurements to be made which are accurate to ± 0,1 pH unit.
6.7 Graduated pipettes or automatic pipettes, of nominal capacities 1 ml and 10 ml.
6.8 Petri dishes, for example of diameter 90 mm.
6.9 Microscope, preferably with phase-contrast, and with slides and cover slips.
6.10 Refrigerator, capable of operating at 5 °C ± 3 °C.AS 5013.24.1 pdf download.