Amino acids in cereals, legumes and oilseeds : variation and prediction of composition as a function of seed nitrogen content in 16 crop species. Nutritional consequences

Abstract

There are sometimes large changes in grain amino acid composition. They are always correlated with those of grain nitrogen content. It has been shown for 16 crop species that these changes can be described by linear relationships between amino acid content in grain and nitrogen content. Some general data is firstly briefly reviewed on seeds, on their storage products, on proteosynthesis occurring during development and also on questions raised by amino acid analysis and expression of composition. The main features of these variations are interpreted from both basic and practical viewpoints. It is emphasized that the same kinds of linear relationships are obeyed, whether they result from environmental or cultivation conditions, or from fertilization or also from genotype. These relationships are defined by two coefficients which have been determined : they are reported in a table for each of the 16 species investigated and for each of the 19 amino acids which can be analysed. Practical and nutritional consequences are discussed, such as magnitude of intraspecific variation of amino acids in grain proteins, compared variations of chemical scores as a function of nitrogen content as well as intra and inter, species variation of the leucine/isoleucine ratio, modifications of the sequence in which amino acids of grains become limiting and also variations of the nitrogen to (true) protein conversion factor. Thus, amino acid composition of grain samples used for animal nutrition can be predicted with high accuracy and reliability from the mean nitrogen content.