Kjeldahl vs Dumas – Overview and Comparison

<p>Protein content is a critical parameter in food and feed analysis, influencing nutritional labeling, ingredient selection, and processing decisions. While spectroscopic techniques like near-infrared reflectance (NIR) can estimate protein and other constituents, they are secondary methods requiring extensive calibration and are highly sensitive to matrix variations. Primary quantitative protein determination traditionally relies on measuring nitrogen using either the wet-chemical Kjeldahl method or the combustion-based Dumas method, with protein values calculated through nitrogen-to-protein conversion factors that vary by material type.</p> <p>The Kjeldahl method has long been accepted across the food and feed industries but is slow, chemically intensive, and can result in incomplete nitrogen recovery due to modern catalyst limitations. In contrast, advancements in instrumentation have made the Dumas combustion method a robust, high-throughput alternative that avoids hazardous reagents and reduces analysis times to just a few minutes. Modern systems like the LECO 828 and 928 series support a wide range of matrices, simplify sample introduction, and provide consistent nitrogen measurement without matrix-dependent calibration.</p>