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%.
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References
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© 1996 Plenum Press, New York
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Delhaye, S., Landry, J. (1996). The Tryptophan Content in Protein of Cereal Grains and Legume Seeds as a Function of Nitrogen Content. In: Filippini, G.A., Costa, C.V.L., Bertazzo, A. (eds) Recent Advances in Tryptophan Research. Advances in Experimental Medicine and Biology, vol 398. Springer, Boston, MA. https://doi.org/10.1007/978-1-4613-0381-7_107
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DOI: https://doi.org/10.1007/978-1-4613-0381-7_107
Publisher Name: Springer, Boston, MA
Print ISBN: 978-1-4613-8026-9
Online ISBN: 978-1-4613-0381-7
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