Estudo do valor nutricional da proteina de feijão-comum (Phaseolus vulgaris, L.), feijão-de-corda (Vigna unguiculata, L.), ervilha (Pisum sativum, L.) e grão-de-bico (Cicer arietinum, L.) utilizando marcação com nitrogenio 15

AUTOR(ES)
DATA DE PUBLICAÇÃO

1990

RESUMO

The aim of this work was to study the value of the protein of the pea (Pisum sativum, L.), the common bean (Phaseolus vulgaris, L.), the cow pea (Vigna unguiculata, L. Walp.) and the chick, pea (Cicer arietinum, L) , by the way of the use of nitrogen 15 (15N) as a tracer. In order to be incorporated to the protein, seeds from pure varieties of grainswere planted in experimental patches wich received fertilizing of (NH4)2SO4 enriched with 10,0 atoms of 15N %. The use of pure varieties and the homogeneity of the culture treatment made it possible to eliminate variables such as genetical characteristics and environmental conditions wich interfered in the results of the chemical and nutritional valuation of the grains. The seeds wich were obtained were analised in relation to the proximate composition and of amino acids, cooked and freeze dried and the material obtained was used as a source of protein in the composition of diets for albino Wistar rats in a randomized assay. The control group received a diet containing commercial casein as a source of protein and another group received a diet without protein. The animals were mantained in controlled conditions of temperature and cycles of light, submitted to a 24 hour- fasting and followed by a 48 hour period to get adapted to the diets, with food and ater ad libitum in growth cages. Right after, they were transfered to metabolic cages where they remained for 4 days, with feces collect at each 24 hours. A determination of total nitrogen and N was made in the feces from the both periods and in the urine obtained in the balance period, as well as the control of weight gain and the ingestion of diet. The chemical determinations showed that among the studied leguminous, the chick pea presented content of crude protein 2 5% lower than the others and around 3 00% more total lipids. The composition of amino acids showed that the pea presented the least content of sulphur containing ones, resulting in the lowest value of chemical score. The results of the biological assays were submitted to one way analisys of variance (ANOVA). It was possible to estabilish a relation between the weight gain and the retention of nitrogen expressed by positive and moderate linear regression, with a correlation coefficient of 0,7616 (p <0,01). The presumption that the period of 4 8 hours following the fasting would be enough for the adaptation of the animals to the diets was confirmed by the stabilization of the levels of excretion of endogenous nitrogen wich presented an acelereted decrease in this period and after did not differ during the balance period (p <0,05), showing a strong and negative potential regression with coefficients always over 0,9500 fp <0,01). The quantification of endogenous nitrogen by applying the isotope showed that the animals fed with cooked leguminous diets excreted around 2 to 2,5 times more endogenous material than the animals on diets without protein. Consequently, the indicators of protein quality obtained through the correction by the use of isotope, resulted in values always superior to those obtained by the correction of diet without protein; nevertheless, not always are there significant differences among them. The analisys of indicators point out the performance of the cowpea wich presented the best values of digestibility, biological value and net protein utilization.

ASSUNTO(S)

proteinas leguminosas

ACESSO AO ARTIGO

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