Características del almidón de maíz y relación con las enzimas de su biosíntesis

Blue maize tortillas differ in taste and texture from white maize. These differences may be due to grain hardness or the starch structure, which is influenced by its mechanisms of biosynthesis and affects the structure of its two main components. The aim of this study was to analyze the blue and white maize starch in two development stages of the grain, to associate its morphological and physicochemical characteristics with the structure, and the latter with the enzymes involved in its biosynthesis. We harvested maize 20 and 50 d after pollination (DAP); and quantified starch content in the kernel, isolated and characterized it. We extracted and separated the starch biosynthesis enzymes according to their molecular weight, and used a one-way analysis of variance at a significance level of p≤0.05. Blue maize had higher starch content. In the electrophoretic analysis, the two maize varieties had bands of molecular weight reported for ADP glucose pyrophosphorylase granule bound synthase starch and three isoforms of soluble synthase starch. Furthermore, we found two isoforms of the starch branching enzyme in blue maize, which could alter the pattern of branching of amylopectin, producing highly branched structures with shorter chains, so that the structure of starch at 50 DAP had less available space within the grain structure for the synthesis of amylose and small and less perfect crystals, which were disorganized at lower temperature and enthalpy than those of the white maize starch. The white and blue maize starch biosynthesis differed as isoforms of branching enzymes in each maize produced different structures, which affected their physicochemical properties.