Rohprotein

Rohprotein, or crude protein, is a gross estimate of a food or feed’s protein content based on its total nitrogen content. The basic assumption is that most of the nitrogen in the sample comes from protein, and that protein on average contains about 16 percent nitrogen. Therefore, the crude protein value is obtained by measuring nitrogen and multiplying by a conversion factor.

The nitrogen content is typically determined by established chemical methods, most commonly the Kjeldahl method or the Dumas combustion method. After measuring total nitrogen, it is converted to crude protein by multiplying by a factor, usually 6.25. Depending on the material, different factors may be used in practice (for example, some dairy products historically use around 6.38).

Rohprotein has limitations. It does not distinguish between true protein and non-protein nitrogen such as urea or nitrates, and it does not account for amino acid composition or digestibility. As a result, crude protein can overestimate or underestimate the actual dietary protein value for humans or animals, and the fixed conversion factor is a simplification that may not accurately reflect all food types.

In nutrition labeling, animal feed formulation, and agricultural analysis, Rohprotein provides a convenient, comparable metric for assessing and comparing protein content across foods and feeds. For detailed nutrition assessments, measurements of true protein and amino acid profiles are often used in addition to crude protein.