Alpha starch is a term that can refer to two different types of starch: pregelatinized starch and chemically modified starch. In some regions, such as Southeast Asia, alpha starch is used as another term for pregelatinized starch. Pregelatinized starch is a type of starch that has been pre-cooked and dried, resulting in a powder that can be easily dissolved in cold water. It is commonly used as a thickening agent in various food applications.
Chemically modified starch, on the other hand, is a type of starch that has been modified through chemical processes to improve its functional properties, such as its stability, viscosity, and texture.
The modification process can involve adding functional groups to the starch molecules, which can alter its solubility, viscosity, gelatinization temperature, and stability.
One common type of chemically modified alpha starch is acetylated starch. This involves the addition of acetyl groups to the starch molecules, which can increase its water solubility, improve its heat stability, and reduce its tendency to retrograde (i.e. become firm or rubbery upon cooling). Acetylated starch is commonly used as a thickener, stabilizer, and binder in food products such as soups, sauces, dressings, and bakery fillings.
Another type of chemically modified alpha starch is cross-linked starch, which involves the formation of chemical bonds between the starch molecules to increase their stability and reduce their susceptibility to degradation by heat, acid, or enzymes. Cross-linked starch is commonly used as a thickener, binder, and texture modifier in a variety of food products, including dairy products, baked goods, and confectionery.
Other types of chemically modified alpha starch include hydroxypropylated starch, phosphorylated starch, and oxidized starch, each with their own unique properties and applications. Overall, chemically modified alpha starch is a versatile ingredient that can improve the functional properties of starch for a wide range of industrial and food applications.