Best@BUCHI #49: Various Methods for Protein Determination in Milk

Buchi SpeedDigester K-439

Buchi SpeedDigester K-439

Not only does milk taste good, it is also a healthy and nutritious food, in fact one of the most valuable foodstuffs there is. Milk protein, in particular, is very valuable because it contains a large proportion of essential amino acids and is therefore indispensable for the structure of body cells (such as muscles, organs, skin, hormones, enzymes).

Contact Buchi for this study and review our various Kjeldahl products, such as the SpeedDigester K-439 shown on the left, which help improve the accuracy and quality control of protein determination in milk by accounting for the (Non-Protein Nitrogen compounds = NPN).

The consumption of milk is rising strongly on a worldwide basis though primarily in the form of processed dairy products. The food industry processes milk in numerous ways and into many different products, from cheese and bakery products or ice cream production through to uses in meat processing or in the production of ready meals. Since the overall protein content plays an important role both for the payment of milk delivered and for determining the breeding value of cows, it is subject to regular checks.

For many years, the reference method for determining the protein content has been the Kjeldahl method. In this method the nitrogen content of a sample is determined and then multiplied by a specific factor (for milk 6.38) to obtain the protein content. However, as milk also contains other sources of nitrogen (Non-Protein Nitrogen compounds = NPN), these are also included and show up as protein.