Revised EN ISO 21528:2017 for Detection and Enumeration of Enterobacteriaceae in the Food Chain

The International Organization for Standardization (ISO) published the revised EN ISO 21528-1 and EN ISO 21528-2 standards in 2017. In Part 1, a horizontal method for the detection of Enterobacteriaceae is specified, and in Part 2, the enumeration of these organisms, both in food and animal feed samples is stated. The revised standards are also applicable to environmental samples in the area of primary production, food production and food handling. Part 1 is applicable when the microorganisms sought are expected to need resuscitation by enrichment, and when the number sought is expected to be below 100/mL or gram of test sample. Part 2 is applicable when the number of colonies sought is expected to be more than 100/mL or per gram of the test sample. The new Part 1 edition cancels and replaces the first edition EN ISO 21528-1:2004. Part 2 cancels and replaces the first edition of EN ISO 21528-2:2004. Compared to the previous edition, the main changes in Part 1 are considered as major, and in Part 2 as minor.

Procedure Steps for Detection of Enterobacteriaceae according to new EN ISO 21528:2017

Part 1: Detection of Enterobacteriaceae

Revised EN ISO 21528-1:2017 at a glance...

• The pre-enrichment step in Buffered Peptone Water (BPW), followed by enrichment in Enterobacteriaceae enrichment (EE) broth has been changed to enrichment in BPW. The selective enrichtment step has been deleted.
• Confirmation now takes place in glucose OF medium instead of using glucose agar.
• Performance testing for the quality assurance of the culture media has been added.
• Performance characteristics for this method have been added to Annex C.
• Most probable number (MPN) method has become an informative Annex A.

Procedure for Detection and Enumeration of Enterobacteriaceae in the Food chain according to EN ISO 21528:2017

Part 2: Colony-count Technique

New EN ISO 21528-2 at a glance...

• The confirmation step has been changed by replacing glucose agar with glucose OF medium.
• Precision data based on the results of an interlaboratory study using the method according to this revised edition has been included in annex B (informative).

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GranuCult^® granulated media, Readybag^® pre-weighed granulated media in ready-to-use bags, ReadyPlate™, and ReadyTube^® ready-to-use media are all compliant with EN ISO 11133:2014. All information regarding compliance with additional reference standards are displayed on the product label and in the product’s technical information available on our website.

Compliance to revised EN ISO 21528:2017

We are implemented all the requirements described in both parts of the revised EN ISO 21528:2017. The following culture media and accessories described in the revised EN ISO 21528:2017 are available: