Milk and milk products - Enumeration of presumptive Escherichia coli - Part 1 : most probable number technique using 4-methylumbelliferyl-Beta-D-glucuronide (MUG)
ISO 11866-1|IDF 170-1:2005 specifies a combined method for the enumeration of presumptive Escherichia coli and of presumptive coliforms by means of a culture technique involving a liquid medium with MUG, and calculation of the number of presumptive Escherichia coli and/or coliforms per gram or per millilitre by the most probable number (MPN) technique after incubation at 30 °C.
The method is applicable to milk, liquid milk products, dried milk, dried sweet whey, dried buttermilk, lactose, acid casein, lactic casein and rennet casein, caseinate and dried acid whey, cheese and processed cheese, butter, frozen milk products (including edible ices), and custard, desserts and cream.
The method specified in ISO 11866-1|IDF 170-1:2005 is preferred for samples in which comparatively low numbers of presumptive Escherichia coli and/or other presumptive coliforms (less than 100 per gram or 10 per millilitre) are suspected.