gelatinization

Gelatinization is the process by which starch granules dispersed in water swell and lose their crystalline structure when heated, causing the mixture to thicken. In this process, starch granules absorb water and increase in volume as the heat disrupts the organized internal structure. As heating continues, amylose and amylopectin may leach into the surrounding water, granules rupture, and a continuous paste forms. The result is an increase in viscosity that can develop into a gel upon cooling in some systems.

The temperature range and extent of gelatinization depend on the starch source and the presence of other ingredients. Typical onset temperatures fall roughly in the 50–70°C region, with peak viscosity occurring at higher temperatures, and complete gelatinization commonly achieved by around 70–95°C. The exact values vary with starch type (for example, waxy versus high-amylose starches) and with moisture content, heating rate, and shear.

Factors such as sugars, acids, salts, fats, and pH influence gelatinization by altering water availability and starch-starch interactions. Sugars tend to raise the onset temperature by binding water, while acids can promote hydrolysis of starch, affecting viscosity. Fats can coat granules and hinder water access.

Applications include thickening sauces and gravies, baking, and the processing of foods and textiles. Gelatinization is related to gelation, in which cooled, gelatinized starch pastes may form a semi-solid gel as molecular networks develop. Techniques such as differential scanning calorimetry and rheology are used to study gelatinization.