Changes in starch properties of corn tortillas during storage

Starch properties of corn tortillas were characterized during storage. Tort illas were chopped into pieces. macerated with ethanol, centrifuged, extrac ted again with ethanol, centrifuged, dried, and ground into flour to dehydr ate and stabilize starch. Water absorption and watts solubility at 25 degre es C. starch pasting properties, and amount and molecular weight of starch extracted at 95 degrees C in water were quantified. Increased levels of sol uble amylopectin and increased cold paste viscosity distinguished fresh (0, 0.5, and 1 h) from aged (120 h) tortillas. Water solubility at 25 degrees C decreased continuously during storage; whereas, water absorption increase d 0.5 h after baking and then decreased during storage, Rapid changes in st arch properties were stabilized using the dehydration procedure and clearly distinguished by pasting viscosities and other methods, Measured starch pr operties were consistent with very rapid associations (retrogradation) of a mylose and rapid associations of amylose and amylopectin yielding insoluble structures in corn tortillas. Retention of some starch crystal nuclei afte r baking facilitated starch associations that yielded rapid structural chan ges in corn tortillas.