Gelatinisation Starch particles do not dissolve in liquid, instead they form something called a suspension. If liquid is not stirred the starch granules sink to the bottom, stick together and start to form lumps.
Gelatinisation When heated at 60 o C, the starch granules begin to absorb the liquid and swell At 80 o C the particles will have absorbed about five times their volume of water until they burst open and release starch, thickening the liquid. This process is Gelatinisation
Gelatinisation Gelatinisation is complete when the liquid reaches boiling point 100 o C When the sauce cools it goes even thicker, going into a Gel.
Heat starch granules in liquid Starch granules become swollen Starch granules burst The liquid thickens and gelatinizes Starch gelatinizes when heated in a liquid, producing a thickened liquid
Examples of Gelatinisation White Sauce for Lasagne Cheese Sauce Sweet & Sour Sauce
Modified Starch This is starch that has been altered to perform additional functions to react to different processes. These are sometimes called SMART starches. Modified starch is used to thicken food when boiled water is added e.g. Cup a soup, dried custard or Pot Noodle.
Food & Drink: Food for thought - What is modified starch? Roy Ballam, British Nutrition Foundation
The starch in some canned soups is bonded with phosphate, which allows it to absorb more water and so the soup from does not separate.
Fish batter contains an oxidised starch to make it "stickier" to adhere to the sides of the fish better.
Instant desserts, such as blancmange, use a pre-gelatinised starch which has been thickened by heat, then dried and added to the product.
Pizza, to stop the tomato sauce spilling off during baking, a starch treated with a chlorine solution is often added to the topping. This produces a gel that thickens during cooking, but goes runny when cooled.