The determination of protein content in food and other organic materials is essential for nutritional labelling, quality control, and regulatory compliance. Two widely used primary methods for nitrogen-based protein quantification are the Kjeldahl Method and the Dumas Method. Each method has its advantages and limitations, and the choice of method depends on the specific application, sample type, and required accuracy.
The Kjeldahl Method: Samples are digested in a temperature-controlled heating block with sulphuric acid, potassium sulphate and copper/titanium catalyst. Following digestion, the ammonia is liberated, steam distilled and titrated against standard acid. Protein is calculated from N content, using appropriate factors (6.25 for most products, 6.38 for dairy). Reported as Protein g/100g.
The Dumas Method: Total protein is determined using nitrogen analysis. The sample is combusted with oxygen and the gases containing nitrogen oxides are collected. With helium as the carrier gas, an aliquot of combustion gas containing nitrogen oxides is reduced to nitrogen. The nitrogen is measured with a thermal conductivity detector using helium as a reference. Nitrogen concentration is then converted to protein using a conversion factor. The analysis takes approximately four minutes making it a preferred method suitable for testing high-throughput labs.
AsureQuality has verified and implemented global standards, including IDF, AOAC, and GB methods, to demonstrate its expertise in protein analysis across diverse matrices such as Milk and Milk Products and all type of foods.
More information
For further detail about protein testing using the Kjeldahl and Dumas Methods, please read: Kjeldahl and Dumas Methods for Protein Quantification
Minimum sample size required for analysis is 20gms.
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