DIN EN ISO 16634-2:2016-11

This part of ISO 16634 specifies a method for the determination of the total nitrogen content and the calculation of the crude protein content of cereals, pulses and milled cereal products. The procedure should be considered from the point of view of quality determination. This method, like the Kjeldahl method, does not distinguish between protein nitrogen and non-protein nitrogen. For the calculation of the protein content, various conversion factors are used. Samples are converted into gases by heating in a combustion tube. Interfering components are removed from the resulting gas mixture. The nitrogen compounds in the gas mixture, or a representative part of them, are converted to molecular nitrogen which is quantitatively determined by a thermal-conductivity detector. The nitrogen content is calculated by a microprocessor. The committee responsible for this standard is NA 057-05-06 AA "Getreide und Getreideerzeugnisse" ("Cereals and cereal products") at DIN.