Extraction and characterization of starches from pigmented rices.

The aim of this work was to extract and characterize starch from three varieties of pigmented rice (named white, red and black), preserving the bioactive compounds. The extraction yield was 44.0%, 47.0% and 35.7%, respectively. The scanning electron microscopy showed that the granules of the three varieties presented polygonal and angular format and absence of impurities. The chemical analyzes, showed more than 83.0% of carbohydrates in the three compositions. There was retention of the phenolic compounds from the raw material in the starches. With regard to pasting properties of the starches, differences were observed in initial temperature, which was of 80.6 °C, 79.1 °C and 88.8 °C for the starches of white, red and black rice, respectively. Black rice starch also showed slightly higher crystallinity and thermal stability than white and red rice starches. Gels of red rice starch have higher syneresis in five freeze-thaw cycles, when compared to the others.