Starch thickening properties are based on its ability to absorb and retain water. When heated in water, the starch granules swell and release amylose, a type of starch molecule, which forms a gel-like network that entraps water. The thicker the gel network, the higher the viscosity and the thicker the resulting liquid will be. The temperature, time, and concentration of starch all influence the degree of thickening. The properties of starch also depend on the type of starch, for example, native starches such as corn and potato tend to thicken at a lower concentration than modified starches such as pre-gelatinized or instant starches.
The gelling properties of starch refer to its ability to form a gel when exposed to specific conditions of temperature, pH, and concentration. The type of starch, degree of gelatinization, and presence of other ingredients can all influence the gelling properties of starch. Starch gels can range from a free-flowing liquid to a rigid solid, depending on the conditions of preparation and the specific type of starch used. This gelling property is utilized in a wide range of food applications, including thickeners for sauces, fillings for baked goods, and as stabilizing agents in various products.