Extraction and Characterization of Starch from Alkaline Cooked Corn Masa

Starch granules undergo structural and morphological changes during food processing unit operations as they interact with other food ingredients. This study was conducted to isolate and characterize starch granules from corn masa. A proteolytic enzyme, thermolysin, was effective in separating and isolating starch granules from endosperm proteins present in masa. The efficiency of starch extraction using thermolysin was 74% (w/w), and subsequent analyses showed that the isolated granules were free of contaminants. Starch samples were characterized using light microscopy, SEM, DSC, and XRD. Starch granules isolated from masa had undergone internal structural changes and some granules (approximately equal to 40%) lost birefringence during nixtamalization. These internal changes occurred, in most cases, without visible alterations in general granular morphology. Nixtamalized granules underwent changes mostly consistent with a "heatmoisture treatment" process.