This part of ISO 17997|IDF 29 specifies a routine method for the direct determination of the casein-nitrogen content of bovine milk. The method can be modified for milk from other species or liquid dairy products. NOTE Casein nitrogen will decrease with milk storage time due to casein breakdown even at 4 °C. The casein nitrogen of heat-treated milk will be artificially high because of whey-protein denaturation.
GSO ISO 17997-2:2014 history
2014GSO ISO 17997-2:2014 Milk -- Determination of casein-nitrogen content -- Part 2: Direct method