Native starch modified by using physical, chemical or biological methods is referred to as modified starch. Native starch is modified so as to enhance its properties such as thermal stability, acid resistance, texture, viscosity, gelatinization time, etc. Examples of modified starch are acid-treated starch, dextrin, bleached starch, oxidized starch, alkaline modified starch etc.
Tapioca starch may be derived from the roots of cassava plant. Three methods are used to modify native starch: physical, chemical and biological.
Physical methods: the molecular structure of the starch is modified by using heat or other dynamic means of energy. Change in the molecular structure results in change in properties. Examples include pre-gelatinized starch, heat treatment starch, annealing starch etc.
Chemical methods: A chemical reaction is used to introduce a compound such as phosphate, acetate or ether into the starch structure or cutting the glucose unit in the starch or cross-linking to modify its native properties. Examples are Hydroxyethylated Starches, Starch acetate etc
Biological methods: Using enzymes, the number of amylose and amylopectin molecules are modified and correspondingly the properties of the starch change. Examples are high amylase starch and waxy starch.