Comparison of kjeldahl and dumas methods for determining protein contents of soybean products
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The Kjeldahl and Dumas methods for quantifying nitrogen content were compared using nine soybean products having protein contents ranging from 0.5 to 90%. In addition to comparing day-to-day variability of the Dumas method, differences between and variabilities of two Kjeldahl systems and Kjeldahl operators were also evaluated. The Kjeldahl method gave slightly, but significantly, lower values than did the Dumas method. Both the Kjeldahl and Dumas methods had equivalent variabilities (same SD about the means). The ratios between the means for the Kjeldahl and Dumas (K/D) protein values ranged from 0.66 to 1.03. The conversion equation y=−0.00536+0.97188x (R 2=0.9997) was developed and validated to convert from Dumas to kjeldahl protein concentrations.
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- Comparison of kjeldahl and dumas methods for determining protein contents of soybean products
Journal of the American Oil Chemists' Society
Volume 80, Issue 12 , pp 1169-1173
- Cover Date
- Print ISSN
- Online ISSN
- Additional Links
- Dumas nitrogen
- Kjeldahl nitrogen
- soy protein
- Industry Sectors
- Author Affiliations
- 1. Department of Food Science and Human Nutrition, Iowa State University, 2312 Food Science Bldg., 50011-1061, Ames, IA
- 2. Center for Crops Utilization and Research, Iowa State University, 50011-1210, Ames, Iowa
- 3. Department of Statistics, Iowa State University, 50011-1210, Ames, Iowa