Starches are modified for a number of reasons. Starches may be modified to increase their stability against excessive heat, acid, and freezing; to change their texture; or to lengthen or shorten gelatinization time.
A modified starch may be an instant starch which thickens and gels without heat; or a cook-up starch, such as Colflo 67, which must be cooked like regular starch.
Other treatments may produce modified starch with different E numbers, such as alkaline-modified starch (E1402), bleached starch (E1403), oxidized starch (E1404), enzyme-treated starch (INS: 1405), acetylated starch (E1420), and acetylated oxidized starch (E1451).
Pre-gelatinized starch is used to thicken instant desserts, allowing the food to thicken with the addition of cold water or milk. Similarly, cheese sauce granules (such as in Macaroni and Cheese or lasagna) or gravy granules may be thickened with boiling water without the product going lumpy. Commercial pizza toppings containing modified starch will thicken when heated in the oven, keeping them on top of the pizza, and then become runny when cooled. A suitably-modified starch is used, quite successfully (with respect to the taste), as a fat substitute for low-fat versions of traditionally fatty foods, e.g., reduced-fat hard salami having about 1/3rd the usual fat content. For such uses, it is an alternative to the product Olestra.
Modified starch is added to frozen products to prevent them from dripping when defrosted. Modified starch, bonded with phosphate, allows the starch to absorb more water and keeps the ingredients together. Modified starch acts as an emulsifier for French dressing by enveloping oil droplets and suspending them in the water. Acid-treated starch forms the shell of jelly beans. Oxidized starch increases the stickiness of batter.