How a simple Kjeldahl method can significantly exceed the strict result requirements of ISO 8968-1 for protein

Regulations, norms and standards shape today’s economy and define working practices in almost every industry, including the food and beverages industry. In this specific case study, we considered milk and the repeatability of protein analysis in milk.

It is precisely this repeatability for protein content according to the Kjeldahl method that is defined in official norms like AOAC 991.20 or ISO 8968–1 as 0.038% protein, making it an international standard for laboratories.

Our aim was to optimise the official repeatability by varying the digestion parameters. This analysis used the KJELDATHERM KBL20s digestion block, the TURBOSOG gas scrubber and the VAPODEST 50 S C distillation system from C. Gerhardt. The various sets of analytical results were then evaluated and compared. For a detailed description of the process and the results, see the PDF document.

  • Analyt: Milk
  • Sample parameter: Protein
  • Method(s): Kjeldahl method
  • Standard(s): AOAC 991.20 / ISO 8968-1

Instruments for protein determination according to Kjeldahl