Amino acid composition of wheat grain. 1: Changes during development

Abstract

A B S T R A C TThe changes in the composition of free and total amino aciak in wheat grain during development are described: the experiment was performed in a growth chamber with three varieties of winter wheat (Triticum aestivum L.): Splendeur, Hobbit and Maris Huntsman. The changes in the total composition of amino acids of the grain as development progressed were consistent with an increase in the proportion of storage proteins. A t 15 days after anthesis, the relative amount of glycine increased, suggesting that at this moment the proportion of gliadins was relatively low. The relative amount of arginine increased in mature grain, showing that at times close to maturity the relative proportion of synthesis of a protein fraction rich in this amino acid increased. Free glutamate, proline and arginine decreased at 15 days to a greater extent than the other amino acids and was present in low relative amounts during the period of maximum protein synthesis in the grain; these three amino acids could be the most limiting for protein synthesis in grain. In the free fraction the following showed a similar pattern of change during grain development: aspartate, arginine and histidine on the one hand, and on the other alanine, valine, leucine, isoleucine, threonine, phenylalanine and tyrosine; moreover both groups were inversely correlated. Glycine and lysine were directly related to each other and inversely to glutamate.

Genotypic Variability on Grain Yield and Grain Nutritional Quality Characteristics of Wheat Grown under Elevated CO2 and High Temperature

“…Despite the similarity between nitrate and sulphate assimilatory pathways [ 60 ], their regulation in response to the availability of the respective nutrient ions and the environment is different [ 61 ]. The observed association is relevant because metabolic proteins (albumin, globulin), which account for 15–20% of the total wheat grain protein, are rich in S-containing amino acids (i.e., cysteine and methionine), as well as in lysin [ 9 , 62 ]. Hence, it is tempting to speculate that a preferential decline of metabolic proteins is likely to make the wheat grain quality poorer with regard to nutritional value, irrespective of any further change in gluten storage proteins responsible for grain processing quality.…”

Formation of Vinylogous Compounds in Model Maillard Reaction Systems

“…Therefore, the formation of corresponding vinylogous compounds in foods is not clear-cut (see Figure 1) and must be studied on a case-by-case basis, taking into account the availability of free amino acids and sugars in the raw agricultural commodity and thermal-processing conditions. Gln and Glu are abundant amino acids present in a free form in many different foods such as wheat (26,27), soybean (28), almonds (28), cocoa (29), and coffee (30). Hence, the Maillard reaction may contribute significantly to the formation of 2-Pyr levels in cooked and roasted foods.…”

Gradients of Gluten Proteins and Free Amino Acids along the Longitudinal Axis of the Developing Caryopsis of Bread Wheat

“…The mechanisms which control the accumulation of proteins in the different cells and tissues of the grain are not known but appear to be both genetically programmed and influenced by environmental factors. ,− The requirement for nutrients (mainly amino acids) varies during the development of the wheat caryopsis. − In the early stages, for about the first 10 days after fertilization, nutrients are required to support cell division and expansion, particularly of the starchy endosperm cells, to establish the basic structure of the grain. , After this stage the main nutrient requirement of the starchy endosperm is to support the synthesis and deposition of storage compounds, mainly starch and protein . By contrast, the growth of the embryo continues throughout grain development.…”