What is non-protein nitrogen?
This is a normal part of milk. The non-protein nitrogen (NPN) fraction is composed of urea and other low molecular weight nitrogen containing compounds such as creatine and creatinine. About 50% of the NPN in milk is urea, and variation in NPN is attributed primarily to variation in urea content. Non-protein nitrogen has little nutritional value and does not contribute to cheese yield. Therefore, it does not have the same economic value as “true” milk protein to either the processor or the consumer.
