Physicochemical and biochemical characterization of starch granules isolated of pigmented maize hybrids

In this study, the morphological and physicochemical of pigmented maizes as well as the initial characterization of the corresponding starch granule enzymes are described. Starch granules were isolated from blue, black, and white maize. They were analyzed using scanning electron microscopy, particle size distribution, pasting characteristics, sorption isotherms, differential scanning calorimetry, and two-dimensional gel electrophoresis. The morphology of the starch granules of pigmented maizes was different from the granules of white maize; the pattern was related to the endosperm type of these varieties. The average starch granule size was higher for black than for white and blue maizes. The average gelatinization temperature was similar in the three starches, but the pigmented maizes hail higher gelatinization enthalpy; black maize starch showed the lowest enthalpy of retrogradation. These results indicated that the starches from the three maizes analyzed had different organization level. Black maize starch showed the highest peak viscosity followed by white and blue maize starches. In the gel electrophoresis three starch granules presented one main spot at pl of 5 and MW of 60 kDa that corresponds to the granule-bound starch synthase. Blue and white starches presented some spots near 97 kDa at pl of 5.3-5.7 (white maize) and 5.1-5.5 (blue maize), spots that were not observed for black maize starch. The morphological and physicochemical characteristics of maize starch are related to the enzymes involved in its biosynthesis.