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The Tryptophan Content in Protein of Cereal Grains and Legume Seeds as a Function of Nitrogen Content

A Reappraisal of Tryptophan Score
  • S. Delhaye
  • J. Landry
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 398)

Abstract

The tryptophan content ([Trp]) in the dry matter (DM) of wheat, maize, barley, sorghum, rice, pearl millet grains, pea and broad bean seeds is evaluated from samples, with various nitrogen contents ([N]DM) and genotypes, using a procedure that has been shown to be strictly quantitative.

The determination of linear correlations between [Trp]DM and [N]DM, and between the tryptophan content in protein ([Trp]N) and [N]DM or 1/[N]DM for every species leads to the following observations: (1) [Trp]DM and [N]DM are linearly related. The data show that previous reports of similar relationships underestimate tryptophan by 10 ± 5% owing to tryptophan degradation during alkaline hydrolysis preparatory to analysis; (2) the linear correlations between [Trp]N and 1/[N]DM, resulting from linear relationships [Trp]DM and [N]DM display coefficients of determination (r2) far lower than 1 and similar to those found for linear correlations between [Trp]N and [N]DM; (3) [Trp]N increases with [N]DM increasing for rice and pearl millet while it decreases for all other species.

In conclusion: (1) linear relationships between tryptophan and nitrogen have a low predictive value; (2) the nutritional score of tryptophan of foods and feeds, as calculated from the determination of tryptophan using a procedure involving alkaline hydrolysis, is generally underestimated by 10%.

Keywords

Nitrogen Content Pearl Millet Broad Bean Phase High Performance Liquid Chromatography Legume Seed 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. Heimbeck, W. and Balschukat, D., 1990, in: “The Amino Acid Composition of Feedstuffs”, Degussa, Hanau, GermanyGoogle Scholar
  2. Landry, J. and Delhaye, S., 1992, Simplified procedure for the determination of tryptophan of foods and feedstuffs from barytic hydrolysis, J Agric Food Chem., 40: 776CrossRefGoogle Scholar
  3. Mossé, J., and Huet, J. C., 1990, Amino acid composition and nutritional score for ten cereals and six legumes or oilseeds: causes and ranges of variations according to species and to seed nitrogen content, Sci Aliments, 10: 151Google Scholar
  4. Slump, P., Flissebaalje, T. D. and Haaksman, I. K., 1991, Tryptophan in food proteins: a comparison of two hydrolytic procedures, J Sci Food Agric., 55: 493CrossRefGoogle Scholar

Copyright information

© Plenum Press, New York 1996

Authors and Affiliations

  • S. Delhaye
    • 1
  • J. Landry
    • 1
  1. 1.Laboratoire de Chimie BiologiqueINRA, INA-PGThiverval GrignonFrance

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