Comparison of the Kjeldahl method, Dumas method and NIR method for total nitrogen determination in meat and meat products

Željko A. Mihaljev, Sandra M. Jakšić, Nadežda B. Prica, Željko N. Ćupić, Milica M. Živkov-Baloš

Volume 21, Issue 4;
Pages: 365-370; 2015
ISSN: 2069-0053 (print) (former ISSN: 1453-1399), Agroprint;
ISSN (online): 2068-9551
In this article the results on the content of total nitrogen (crude protein) obtained using the following three methodologies were compared: the Kjeldahl method (most commonly used and well-known), the Dumas method (total combustion method) and NIR (Near InfraRed) for rapid on-line analysis. The analysis involved the samples of turkey meat and diverse meat products (pate, sausages, hot dog). The obtained results revealed the precision rate below 2% for the Kjeldahl method, whereas precision rate for the Dumas method ranged within an interval 2-4%. NIR method proved most rapid in determining protein content; however, its precision ranged between 3% and 6%. Potential statistically significant differences between the results on crude protein content in meat and meat products obtained by different methodologies were determined using analysis of variance. The Kjeldahl method, because of its high precision and very small values of intervals of variation, have made it the major method for the estimation of protein in foods. The Dumas method for the quantitative determination of organic nitrogen was at least as precise as the Kjeldahl method, but considerably faster. NIR method has high relative standard deviation and is particularly useful for rapid on-line analysis of the protein content.
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