Nitrogen 15 abundance in protein fractions of beans fertilized with (15NH4)2SO4

Scientia Agricola

Saula Goulart Chaud²  Admar Costa De Oliveira²  Paulo César Ocheuze Trivelin¹ 

[1] ,UNICAMP FEA Depto. de Planejamento Alimentar e NutriçãoCampinas SP

关键词: Phaseolus vulgaris L.;    stable isotopes;    isotopic label;    nutritive value;    experimental nutrition;    Phaseolus vulgaris L.;    isótopos estáveis;    marcação isotópica;    valor nutritivo;    nutrição experimental;   

DOI  :  10.1590/S0103-90162002000400023

来源: SciELO

【 摘 要 】

Studies evaluating the protein nutritive value of beans labelled with 15N, ussing nitrogen balance and the quantitation of faecal and urinary endogenous nitrogen, determined by isotopic dilution, have been extensively used. The objective of this research was to verify if the isotopic labelling of raw, freeze dried beans (Phaseolus vulgaris L., cultivar Piratã 1) with 1.394 atoms%15N, resulted in the same abundance of the whole flour and of the protein fractions extracted from the beans with 0.5 mol L-1 NaCl. The isotopic abundance found in the whole bean flour, in the protein extract, in the globulin and albumin fractions were respectively: 1.394 ± 0.011; 1.403 ± 0.012; 1.399 ± 0.007 and 1.399 ± 0.028 atoms % of 15N, presenting no difference (P > 0.05). However, a difference was found (P < 0.05) between the above mentioned abundances and the isotopic abundance found in the nitrogen of the proteins in the extraction residue, which was 0.969 ± 0.084. Since the abundances did not differ, the protein nutritive indexes, such as digestibility and biological value, determined from the nitrogen balance and corrected for isotopic dilution, would not be affected by extracting the proteins from the beans with 0.5 mol L¹ NaCl. If working with the nitrogen balance of the residual proteins after extraction and even with the whole flours, these indexes could present incorrect values, since the isotopic labelling of the residual proteins was less than that of the protein fractions.

【 授权许可】

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