Final answer:
Inspectors use nitrogen content tests to estimate protein content because they are universal, encompassing all nitrogen-containing compounds, and less influenced by other substances compared to the Bradford assay.
Step-by-step explanation:
Food safety inspectors might use an overall nitrogen content test instead of a Bradford assay to determine the protein content in a product because the nitrogen content test is a more universal and indirect method of estimating protein content. While the Bradford assay is specific to proteins, it can be influenced by the presence of other substances that might interfere with the colorimetric measurement. On the other hand, the nitrogen content test, based on the fact that proteins contain a significant amount of nitrogen, provides a global measure of all nitrogen-containing compounds (which are assumed to be primarily proteins in food samples).
The nitrogen content test, often done through the Kjeldahl or Dumas methods, measures total nitrogen which can then be converted to an estimated protein content by using a conversion factor (typically 6.25, as most proteins are approximately 16% nitrogen by weight). This method is more inclusive of all potential protein forms and is less likely to be influenced by non-protein components in the food, making it a reliable method to ensure food safety standards are met.