AS 5013.3:2022 pdf free download – Food microbiology Method 3: Microbiology of food and animal feeding stuffs — Horizontalmethod for the detection and enumeration of coliforms — Most probable number technique (Iso 4831:2006, MOD)

AS 5013.3:2022 pdf free download – Food microbiology Method 3: Microbiology of food and animal feeding stuffs — Horizontalmethod for the detection and enumeration of coliforms — Most probable number technique (Iso 4831:2006, MOD).
AS 5013.3 gives general guidelines for the detection and the enumeration olcollforms.
It is applicable to
— products intended for human consumption and for the feeding of animals, and
— environmental samples in the area of fuod production and food handling.
Enumeration is carried out by calculation of the most probable number (MPN) after incubation in a liquid medium at 30°C or 37°C.
NOTE The temperature Is subject to agreement between the parties concerned, In the case of milk and milk products, the temperature of incubation Is 30 C.
This enumeration method is applicable when the number sought is expected to be in the range I to 100 per millilitre or per gram of test sample.
A limitation on the applicability of this International Standard is imposed by the susceptibility of the method to a large degree of variability. The information given in Clause 11 provides guidance on the applicability of the method and on the Interpretation of the results.
2 NormatIve references
The following referenced documents are indispensable for the application of this document, For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 6887 (all parts), Microbiology of food and animal feedi ng stuffs — Preparation of test samples. initial suspension and decimal dilutions for microbiolo,qical examination
ISO 7218. Microbiology of food and ammo? feeding stuffs — Genera? requirements and guidance for microbiological exommatrons
ISO 8261, Milk and milk products — General guidance for the preparation of test samples. initial suspensions and decimal dilutions for microbiological examination
ISO/TS 11133-1. Microbiology offood and animal feeding stuffs — Guidelines on preparation and production of culture media — Part 1: General guidelines on quality assurance for the preparation of culture media in the laboratory
ISO/TS 11133-2:2003. Microbiology of food and animal feeding stuffs — Guidelines on preparation and produce-ion of culture media — Part 2: Practical guidelines on performance testing of culture media
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
9.1.2.1 Depending on the limit of detection that is required, x ml of the test sample if liquid, or x ml of the initial suspension In the case of other products, is transferred to a tube containing 10 ml of double- strength selective enrichment medium 5.3.1a)J when 1 ml cxc 10 ml, or to a tube containing 10 ml of single-strength selective enrichment medium [5.3Jb)I when x s 1 mt
9.1.2.2 Leave the tube of doublestrength medium (9J.2J.) in the Incubator (62) set at 30 °C or 37°C (as agreed) for 24 h ± 2 h.
9.1.2.3 Leave the tube of single-strength medium (9.12.1) in the incubator (62) at 30°C or 37 C (as agreed) for 24 h ± 2 h or, if neither gas formation nor opacity preventing the detection of gas formation is observed at this stage, continue Incubation for another 24 h ± 2 It
9.1.3 ConfirmatIon (see FigureA3)
9.1.3.1 From the incubated tube from 9.122. inoculate with a loop (6.3) a tube of confirmation medium (5,4). Incubate in the incubator (62) set at 30 °C or 37 C (as agreed) for 24 h i 2 h or, if gas formation Is not observed at this stage, for 48 h ±2 h.
9.1.3.2 Carry out the same procedure as described in 9J.2.1 for the incubated tubes from 9.L2. showing gas formation, or opacity preventing the detection of gas formation, when either of these Features Is first observed (Le. after 24 h ± 2 h or after 48 h ± 2 h).
9.1.4 Interpretation (see FIgureAI)
A tube from 9.111 or 9.L3.2 in which gas formation is observed after 24 ii ± 2 h or 48 h ± 2 h is considered as a positive tube.
9.2 Enumeration method (MPN) (see Figure A2)
9.2.1 Test portion, initial suspension and dilutions
See ISO 6887 (relevant part), ISO 8261 or the specific International Standard appropriate to the product concerned.
Prepare a sufficient number oldllutlons to ensure that all the tubes corresponding to the final dilution yield a negative result.
9.2.2 Inoculation and incubation
9.2.2.1 It Is usual that there isa combination of three tubes for each dilution series. However, for some products and/or each time that results of greater accuracy are required, it maybe necessary to inoculate series consisting of more then three tubes (e.g. five tubes). For these cases, for the calculation of the MPN see the relevant tables Included in ISO 7218.