The comparison of Dumas and Kjeldahl method for the determination of the protein in different dairy products
Project no. 20520 · Status: Kapanmış · 2019
Summary
The determination of protein, is one of the main components in dairy products, is important. Kjeldahl method is used as a reference method for protein determination in dairy products. However, this method requires a long analyzing time. However, Dumas method is a fast method. The results of Dumas method should be compared with those of Kjeldahl method to determine its usability in dairy products. Therefore, in this study, it was aimed to determine the relation between these two methods in different dairy products (cheeses, yoghurts, drinking milks, cheese powder and milk powder) widely consumed in Turkey. 3 pasteurized milks, 6 UHT milks, 4 white cheeses, 4 kashar cheeses, 4 tulum cheeses, 3 whey cheeses, 8 yoghurts and 1 milk powder were used. In addition, 3 different types of cheese powder (full-fat, low-fat and low-fat with microparticulated protein) samples were also used in the analyzes. The differences between the protein results obtained using Kjeldahl and Dumas methods were found to be significant in samples. The results obtained from Kjeldahl method were found to be higher than those of Dumas method. Especially in the liquid-fluid dairy products (milk and yoghurt) and whey cheese, the deviations in the Dumas method were found to be higher, but the deviations and differences between two methods were found lower in solid dairy products containing high protein levels. As a conclusion, Dumas method should not be used in milk and yoghurts, but this method could be used for obtaining an idea about the protein content of samples containing high protein levels such as cheese and powders.