STARCH RETROGRADATION

Starch granules heated in excess water undergo an order-disorder phase transition called gelatinization (1) over a temperature range characteristic of the starch source. This phase transition is a nonequilibrium process associated with the diffusion of water into the granule, hydration and swelling of the Starch granules, uptake of heat, loss of crystallinity, and amylose leaching (1-3). On cooling, the starch chains (amylose and amylopectin) in the gelatinized paste associate, leading to the formation of a more ordered structure. These molecular interactions are termed collectively ''retrogradation'' and have important textural and dietary implications (not covered in this review). This review summarizes the present knowledge on amylose gelation and amylopectin crystallization, and on the factors that influence starch retrogradation.