ISO 4832 pdf download Microbiology of food and animal feeding stuffs — Horizontal method for the enumeration of coliforms — Colony-count technique
This International Standard gives general guidelines for the enumeration of coliforms. It is applicable to — products intended for human consumption and for the feeding of animals, and — environmental samples in the area of food production and food handling, by means of the technique of counting colonies after incubation on a solid medium at 30 ◦ C or at 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 technique is recommended when the number of colonies sought is expected to be more than 100 per millilitre or per gram of the test sample.
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 feeding stuffs — Preparation of test samples, initial suspension and decimal dilutions for microbiological examination
ISO 721 8:— 1 ) , Microbiology of food and animal feeding stuffs — General requirements and guidance for microbiological examinations
ISO 8261 , Milk and milk products — General guidance for the preparation of test samples, initial suspensions and decimal dilutions for microbiological examination
ISO/TS 1 1 1 33-1 , Microbiology of food 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 1 1 1 33-2:2003, Microbiology of food and animal feeding stuffs — Guidelines on preparation and production 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.
bacteria which, at the specified temperature (i.e. 30 C or 37 “C, as agreed) form characteristic colonies incrystal violet neutral red bile lactose agar, and which in the confirmation test cause fermentation of lactose withthe production of gas under the test conditions specified in this international Standard
4.1Two poured plates are prepared using a solid selective culture medium, with a specified quantity of the testsample if the initial product is liquid, or with a specified quantity of an initial suspension in the case of otherproducts.
Other pairs of poured plates are prepared under the same conditions, using decimal dilutions of the test sampleor of the initial suspension.
4.2 The plates are incubated at 30 C or 37 C (as agreed) for 24 h.
4.3 The characteristic colonies are counted and, if required, a number of colonies are confirmed byfermentation of lactose.
4.4The number of coliforms per millilitre or per gram of sample is calculated from the number of characteristiccolonies obtained in the plates chosen (see ISO 7218).
5 Culture media and diluents
See lSO 7218, ISO/TS 11133-1 and ISO/TS 11133-2 for the preparation, production and performance testingof culture media.
See ISO 6887 (relevant part), ISO 8261 or the specific lnternational Standard dealing with the product underexamination.