Evaluation and Suppression of Retrogradation of Gelatinized Rice Starch.

Starch starts to retrograde and form a crystalline structure immediately after gelatinization upon heating with water. The retrogradation rate is affected by the starch granule size, degree of polymerization, amylose/amylopectin ratio, starch concentration, water content, and storage temperature. Retrogradation of amylose occurs over a short term, while that of amylopectin occurs over a long term. The degree of starch gelatinization and retrogradation is evaluated by the degree of crystalline structure formation, viscoelastic properties, molecular mobility, and enzymatic digestibility using thermal, rheological, spectroscopic, and chemical techniques. The addition of carbohydrates, lipids, proteins, salts, acids, polyols, and enzymes changes the starch retrogradation rate, and some of these prevent retrogradation.