Journal of Chemical Ecology

, Volume 19, Issue 11, pp 2605–2615 | Cite as

Influence of nonprotein nitrogen on estimation of protein from total nitrogen in fleshy fruits

  • Ido Izhaki
Article

Abstract

The protein content of pulps of 26 fleshy fruit species from east Mediterranean habitats in Israel were estimated using two different methods: (1) the Kjeldahl procedure in which the total recovered nitrogen is multiplied by 6.25 to estimate total proteins, and (2) amino acid analysis by amino acid analyzer. The average protein content obtained by the Kjeldahl procedure was 5.75% (dry weight) while it was only 3.90% when amino acids were analyzed. The higher value of protein content by the Kjeldahl procedure is most likely the result of a relatively high proportion of nonprotein nitrogen compounds (31%) in these pulps. Therefore the 6.25 factor is not valid and a 4.05 factor may be more accurate for assessing the true protein content of these fleshy fruits. The data also suggest that the more accurate estimate of true protein (Y) from Kjeldahl total nitrogen (X) should be based on the highly significant linear regression between these two variables:Y=4.885X−0.6.

Key words

Frugivory seed dispersal amino acids Kjeldahl protein fleshy fruit nutrition secondary compounds plant-animal interactions 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Aoac. 1984. Official Methods of Analysis of the Association of Official Analytical Chemists. AOAC, Washington, D.C.Google Scholar
  2. Albersheim, P. 1975. The walls of growing plant cells.Sci. Am. 232:80–95.Google Scholar
  3. Barnea, A., Yomtov, Y., andFriedman, J. 1991. Does ingestion by birds affect seed germination?Fund. Ecol. 5:394–402.Google Scholar
  4. Berthold, P.B. 1976. The control and significance of animal and vegetable nutrition in omnivorous songbirds.Ardea 64:140–154.Google Scholar
  5. Bondi, A.A. 1987. Animal Nutrition. John Wiley & Sons, New York.Google Scholar
  6. Calvert, J.J. 1985. Food selection by western gorillas (G.g. gorilla) in relation to food chemistry.Oecologia 65:236–246.Google Scholar
  7. Debussche, M., Cortez, J., andRimbault, I. 1987. Variation in fleshy fruit composition in the Mediterranean region: The importance of ripening season, life-form, fruit type and geographical distribution.Oikos 49:244–252.Google Scholar
  8. Ehrlén, J., andEriksson, O. 1993. Toxicity in fleshy fruits—a non-adaptive trait?Oikos 66:107–113.Google Scholar
  9. Elkin, R.G., andGriffith, J.E. 1985. Hydrolysate preparation for analysis of amino acids in sorghum grains: Effect of oxidative pretreatment.J. Assoc. Anal. Chem. 68:1117–1121.Google Scholar
  10. Foster, M.F. 1978. Total frugivory in tropical passerines: A reappraisal.Trop. Ecol. 19:131–154.Google Scholar
  11. Gargiullo, M.B., andStiles, E.W. 1991. Chemical and nutritional differences between two birddispersed fruits:Ilex opaca andIlex verticillata, J. Chem. Ecol. 17:1091–1106.Google Scholar
  12. Hansen, E. 1970. Proteins,in A.C. Hulme (ed.). The Biochemistry of Fruits and Their Products, Vol. 1, Series on Food, Science & Technology. Academic Press, New York.Google Scholar
  13. Harborne, J.B. 1991. The chemical basis of plant defense, pp. 45–59,in R.T. Palo and C.T. Robbins (eds.). Plant Defenses Against Mammalian Herbivory. CRC Press, Boca Raton, Florida.Google Scholar
  14. Herbst, L.H. 1986. The role of nitrogen from fruit pulp in the nutrition of the frugivorous batCarollia perspicillata.Biotropica 18:39–44.Google Scholar
  15. Herrera, C.M. 1987. Vertebrate-dispersed plants of the Iberian Peninsula: A study of fruit characteristics.Ecol. Monogr. 57:305–331.Google Scholar
  16. Herrera, C.M. 1989. Frugivory and seed dispersal by carnivorous mammals, and associated fruit characteristics, in undisturbed Mediterranean habitats.Oikos 55:250–262.Google Scholar
  17. Izhaki, I. 1986. Seed dispersal by birds in an eastern Mediterranean scrublands. PhD dissertation. The Hebrew University of Jerusalem, Israel (in Hebrew).Google Scholar
  18. Izhaki, I. 1992. A comparative analysis of nutritional quality of mixed and exclusive fruit diets for yellow-vented bulbuls.Condor 94:912–923.Google Scholar
  19. Izhaki, I., andSafriel, U.N. 1985. Why do fleshy-fruit plants of the Mediterranean scrub intercept fall—but not spring—passage of seed-dispersing migratory birds?Oecologia 67:40–43.Google Scholar
  20. Izhaki, I., andSafriel, U.N. 1989. Why are there so few exclusive frugivorous birds? Experiments on fruit digestibility.Oikos 54:23–32.Google Scholar
  21. Izhaki, I., Walton, P., andSafriel, U.N. 1991. Seed shadows generated by frugivorous birds in an eastern Mediterranean scrub.J. Ecol. 79:579–590.Google Scholar
  22. Jordano, P. 1988. Diet, fruit choice and variation in body condition of frugivorous warblers in Mediterranean scrubland.Ardea 76:193–209.Google Scholar
  23. Jordano, P. 1991. Fruits and frugivory, pp. 105–156,in M. Fenner (ed.). Seeds: The Ecology of Regeneration in Plant Communities. C.A.B. International, Willingford.Google Scholar
  24. Kool, K.M. 1992. Food selection by the silver leaf monkey,Trachypithecus auratus sondaicus, in relation to plant chemistry.Oecologia 90:527–533.Google Scholar
  25. Levey, D.J., andKarasov, W.H. 1989. Digestive responses of temperate birds switched to fruit or insect diets.Auk 106:675–686.Google Scholar
  26. Lyttleton, J.W. 1973. Proteins and nucleic acids, pp. 63–103,in G.W. Butler and R.W. Bailey (eds.). Chemistry and Biochemistry of Herbage, Vol. 1. Academic Press, New York.Google Scholar
  27. Mack, A.L. 1990. Is frugivory limited by secondary compounds in fruits?Oikos 57:135–138.Google Scholar
  28. Maynard, A.B., andLoosli, J.K. 1969. Animal Nutrition. McGraw-Hill, New York.Google Scholar
  29. Milton, K., andDintzis, F.R. 1981. Nitrogen-to-protein conversion factors for Tropical plant samples.Biotropica 13:177–181.Google Scholar
  30. Parrish, J.W., andMartin, E.W. 1977. The effect of dietary lysine on the energy and nitrogen balance of the dark-eyed junco.Condor 79:24–30.Google Scholar
  31. Piper, J.K. 1986. Seasonally of fruit characters and seed removal by birds.Oikos 46:303–310.Google Scholar
  32. Poddar, S., andLederer, R.J. 1982. Juniper berries as an exclusive winter forage for Townsend's solitaires.Am. Midl. Nat. 108:34–40.Google Scholar
  33. Potter, D.A., andKimmerer, T.W. 1986. Seasonal allocation of defense investment inIlex opaca Ait. and constraints on a specialist leaf miner.Oecologia 69:217–224.Google Scholar
  34. Robbins, C.T. 1983. Wildlife Feeding and Nutrition. Academic Press, New York.Google Scholar
  35. Rogers, M.F., Maisels, F., Williamson, E.A., Fernandez, M., andTutin, C.E.G. 1990. Gorilla diet in the Lope Reserve, Gabon.Oecologia 84:326–339.Google Scholar
  36. Sakai, H.F., andCarpenter, J.R. 1990. The variety and nutritional value of foods consumed by Hawaiian crow nestlings, and endangered species.Condor 92:220–228.Google Scholar
  37. Sedinger, J.S. 1990. Are plant secondary compounds responsible for negative apparent metabolizability of fruits by passerine birds? A comment on Izhaki and Safriel.Oikos 57:138–140.Google Scholar

Copyright information

© Plenum Publishing Corporation 1993

Authors and Affiliations

  • Ido Izhaki
    • 1
  1. 1.Department of BiologyUniversity of Haifa at OranimTivonIsrael

Personalised recommendations