The importance of cereal grains to the nutrition of millions of people around the world is widely recognized. Because they make up such a large part of diets, cereal grains cannot be considered only as a source of energy, as they provide significant amounts of protein as well. It is also recognized that cereal grains have a low protein concentration and that protein quality is limited by deficiencies in some essential amino acids, mainly lysine. Much less appreciated is the fact that some cereal grains contain an excess of certain essential amino acids that influence the efficiency of protein utilization. Maize, after wheat and rice, it is the most important cereal grain in the world, providing nutrients for humans and animals. The nutritional quality of maize is determined by the amino acid makeup of its protein. Maize is deficient in two essential amino acids: lysine and tryptophan. For a balanced nutrition is important not only the amount of amino acids taken over, but the ratio between them, because the disproportion in feed of amino acids composition leads to a complex disorder of protein metabolism. In this paper the protein content and amino acid composition of maize grain was determined. Maize (Zea mays L.) was grown in a series of field plots which received nitrogen only and various rata of applied nitrogen, phosphorus, potassium and microelements as foliar fertilizers. Total N in the maize grain was determined by a Kjeldahl method and protein content by calculation (N x 6.25). Amino acid composition, after subjecting samples to conditions which would hydrolyze protein, was determined by ion chromatographic method developed in the Organic Sustainable Agriculture and Food Safety-ADSA, PLATFORM laboratory. The results obtained indicated that grain yield increase have resulted in lower protein concentration except when the yield increase resulted from nitrogen fertilizer application. Raw protein content of maize grain was ranged between 8.5% and 10.8%. Higher nitrogen application rates alter the amino acid balance thereby reducing the nutritional value.

fertilization; maize; raw protein; amino acids

Presentation: oral