Compilers' Toolbox™ - Non-Protein Nitrogen

Non-Protein Nitrogen in Foods

	Updated 2021-03-29

Apart from protein, foods and feeds contain many other nitrogenous compounds. These non-protein nitrogenous compounds are of interest, because the do not show any protein effect. As protein in foods is most often measured by determining the foods' nitrogen content, it is of great nutritional interest to adjust then total nitrogen content ("crude" nitrogen) found. This is done by subtracting the measured non-protein nitrogen from total nitrogen. Only the

The non-protein nitrogenous compounds include a long range of compounds like free amino acids, purines, pyrimidine, nucleotides, peptides, urea, ammonia compounds, e.g. biogenic amines, phospholipids, creatine/creatinine, nitrate/nitrite and many other compounds.

The amount of non-protein nitrogen varies immensely between different foods from almost none to more than 50% of the nitrogen content.

References

Ariño A., Beltrán J.A., Herrera A., Roncalés P.:
Fish and seafood: Nutritional Value.
Encyclopedia of Human Nutrition (Third Edition), pp. 254-261, 2013.
DOI: 10.1016/B978-0-12-375083-9.00110-0
Bhatty R.S., Sosulski F.W., Wu K.K.:
Protein and Nonprotein Nitrogen Contents of some Oilseeds and Peas.
Canadian Journal of Plant Science, Vol. 53, pp. 651-657, 1973.
Carlson S.E.:
Human milk nonprotein nitrogen: occurrence and possible functions.
Advances in Pediatrics, Vol. 32, pp. 43-70, 01 Jan 1985.
Carratù B., Boniglia C., Scalise F., Ambruzzi A.M., Sanzini E.:
Nitrogenous components of human milk: non-protein nitrogen, true protein and free amino acids.
Food Chemistry, Vol. 81, Iss. 3, pp. 357-362, June 2003.
DOI: 10.1016/S0308-8146(02)00430-2
DePeters E.J., Ferguson J.D.:
Nonprotein Nitrogen and Protein Distribution in the Milk of Cows.
Journal of Dairy Science, Vol. 75, No. 11, pp. 3192-3209, November 1992.
DOI: 10.3168/jds.S0022-0302(92)78085-0
DeVries J.W., Greene G.W., Paynec A., Zbylut S., Scholl P.F., Wehling P., Everse J.M. Moore J.C.:
Non-protein nitrogen determination: A screening tool for nitrogenous compound adulteration of milk powder.
International Dairy Journal, Vol. 68, pp. 46-51, May 2017.
DOI: 10.1016/j.idairyj.2016.12.003
Imafidon G.I., Sosulski F.W.:
Nonprotein nitrogen contents of animal and plant foods.
Journal of Agricultural and Food Chemistry, Vol. 38, No. 1, pp. 114-118, 1990.
Izhaki I.:
Influence of nonprotein nitrogen on estimation of protein from total nitrogen in fleshy fruits.
Journal of Chemical Ecology, Vol. 19, pp. 2605–2615, 1993.
Kjosbakken J.; Larsen H.:
The non-protein nitrogenous compounds of fish used in meal production, with special reference to capelin (Mallotus villosus) [whole fish, white muscle, red muscle, hard roe, soft roe, trimethylamine oxide (TMAO), trimethylamine, taurine, free amino acids, anserine, inosine, inosine monophosphate (IMP), hypoxanthine].
Reports on Nutrition Investigations concerning Norwegian Fisheries Research 1981.
Kurkela R., Koivurinta J., Kuusinen R.:
Non-protein nitrogen compounds in the higher fungi—A review.
Food Chemistry, Vol. 5, No. 2, pp. 109-130, April–June 1980.
DOI: 10.1016/0308-8146(80)90034-5
Lönnerdal B.:
Nutritional Importance of Non-protein Nitrogen.
Protein Metabolism During Infancy, edited by Niels C. R. Raiha.
Nestle Nutrition Workshop Series. Vol. 33. Nestec Ltd., Vevey/ Raven Press, Ltd., New York 1994.
Manimaran U., Shakila R.J., Sivaraman B., Shalini B., Jeyasekaran G., Shanmugam S.A.:
Biochemical Quality Changes During Iced Storage of Indian Octopus (Cistopus indicus).
Journal of Food Quality, Vol. 39, No. 5, pp. 487-495, October 2016.
DOI: 10.1111/jfq.12215
Olalla M., Ruiz-López M.D., Navarro M., Artacho R.:
Nitrogen fractions of Andalusian goat milk compared to similar types of commercial milk.
Food Chemistry, Vol. 113, No. 3, pp. 835-838, 1 April 2009.
DOI: 10.1016/j.foodchem.2008.10.022
Paulsen P., Hagen U., Bauer F.:
Changes in biogenic amine contents, non-protein nitrogen and crude protein during curing and thermal processing of M. longissimus, pars lumborum of pork. European Food Research and Technology, Vol. 223, pp. 603–608, 2006.
DOI: 10.1007/s00217-005-0240-6
Periago M.J., Ros G., Martínez C., Rincón F.:
Variations of non-protein nitrogen in six Spanish legumes according to the extraction method used.
Food Research International, Vol. 29, Iss. 5–6, pp. 489-494, June–August 1996.
DOI: 10.1016/S0963-9969(96)00053-1
Picciano M.F.:
Human Milk: Nutritional Aspects of a Dynamic Food.
Neonatology, Vol. 74, pp. 84–93, 1998.
DOI: 10.1159/000014015
Prosser C.G., McLaren R.D, Frost D., Agnew M., Lowry D.J.:
Composition of the non-protein nitrogen fraction of goat whole milk powder and goat milk-based infant and follow-on formulae.
International Journal of Food Sciences and Nutrition, Vol. 59 No. 2, pp. 123-133, 2008.
DOI: 10.1080/09637480701425585
Raju C.M., Mathew S., Mathew M.:
Comparative Evaluation of Non-Protein Nitrogenous. Compounds in Fishes of Fresh and Brackish Water. Environments.
Fishery Technology, Vol. 47, No. 2, pp. 161-166, 2010.
Rudloff S.; Kunz C.:
Protein and Nonprotein Nitrogen Components in Human Milk, Bovine Milk, and Infant Formula: Quantitative and Qualitative Aspects in Infant Nutrition.
Journal of Pediatric Gastroenterology & Nutrition, Vol. 24 No. 3, pp 328-344, March 1997.
Ruı́z-Capillas C., Moral A., Morales J., Montero P.:
Characterisation of non-protein nitrogen in the Cephalopods volador (Illex coindetii), pota (Todaropsis eblanae) and octopus (Eledone cirrhosa)Food Chemistry, Vol. 76, No. 2, pp. 165-172, February 2002.
DOI: 10.1016/S0308-8146(01)00259-X
Ruska D., Jonkus D.:
Crude Protein and Non-protein Nitrogen Content in Dairy Cow Milk.
Rural Sustainability Research, Volume 32, No. 1, pp. 36-40, December 2014.
DOI: 10.2478/plua-2014-0011
Salimeia E., Variscob G., Rosic F.:
Major constituents, leptin, and non-protein nitrogen compounds in mares' colostrum and milk.
Reproduction Nutrition Development, Vol. 42, No. 1, pp. 65-72, January-February 2002.
DOI: 10.1051/rnd:2002007
Simidu W.:
Nonprotein Nitrogenous Compounds.
Department of Fisheries, Kyoto University, Maizuru, Kyoto, Japan
Sinaga S.M., Lubis I.Y., Silalahi J.:
Analysis of Total Protein and Non Proteinnitrogen in Pakkat (Calamus caesius Blume.) as a Traditional Food of Mandailing Natal by using Kjeldahl Method.
International Journal of PharmTech Research, Vol. 9, No. 12, pp. 543-549, 2016.
Sinaga S.M., Margata L., Silalahi J.:
Analysis of Total Protein and Non Protein Nitrogen in Coconut Water and Meat (Cocos Nucifera L.) by using Kjeldahl Method.
International Journal of PharmTech Research, Vol. 8, No. 4, pp. 552-557, 2015.
Sriket P.:
Comparative study on the characteristics and quality changes during iced storage of black tiger and white shrimps.
Prince of Songkla University, Faculty of Agro-Industry (Food Technology), 2006.
Templeton D.W., Laurens L.M.L:
Nitrogen-to-protein conversion factors revisited for applications of microalgal biomass conversion to food, feed and fuel.
Algal Research, Vol. 11, pp. 359-367, September 2015.
DOI: 10.1016/j.algal.2015.07.013
Van Warde A.:
Biochemistry of non-protein nitrogenous compounds in fish including the use of amino acids for anaerobic energy production.
Comparative Biochemistry and Physiology, Part B: Comparative Biochemistry Volume 91, No. 2,pp. 207-228, 1988.
DOI: 10.1016/0305-0491(88)90136-8
Velankar N.K., Govindan T.K.:
A preliminary study of the distribution of non-protein nitrogen in some marine fishes and invertebrates.
Proceedings of the Indian Academy of Sciences, Vol. 47, No. 4, pp. 202-209, 1958.
Wang H., Pampati N., McCormick W.M., Bhattacharyya, L.:
Protein Nitrogen Determination by Kjeldahl Digestion and Ion Chromatography.
Journal of Pharmaceutical Sciences, Vol. 105, No. 6, pp. 1851-1857, June 2016.
DOI: 10.1016/j.xphs.2016.03.039


	© 2026 Anders Møller, Danish Food Informatics

Non-Protein Nitrogen in Foods