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Extraction and Characterization of Starch from Alkaline Cooked Corn Masa¹

¹A contribution of the University of Nebraska Agricultural Research Division (Journal Series Number 15264), supported in part by funds provided through the Hatch Act. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable. ²Department of Food Science and Technology, University of Nebraska-Lincoln, Lincoln, NE 68583-0919. ³Corresponding author. Phone: 402-472-2814. Fax: 402-472-1693. E-mail address: djackson@unlnotes.unl.edu

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 (≈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 “heat-moisture treatment” process.