Gelatinisation When starches are heated with liquid they

Gelatinisation - When starches are heated with liquid, they swell and will thicken. This is a key process in sauce making, it is known as gelatinisation.

The process of gelatinisation when making a starch based sauce such as a white sauce. • Starch granules spread through the liquid before heating. • The starch granules begin to absorb the liquid when heated to 60 c. • Starch granules begin to swell and as granules get bigger require regular stirring to prevent them sticking together and forming lumps at 80 c. • The granules will burst releasing the starch liquid (amylose) thickening the mixture at 100 c – gelatinisation/ thickening is now complete. • If the sauce cools down a skin can develop and become a solid gel.

In conclusion • It is the flour in a sauce that causes it to thicken by gelatinisation. • For gelatinisation to take place the sauce needs to be heated. • During this process, the starch grains swell and grow up to 5 times their normal size. • Starch gelatinisation is when the starch granules break open to release the amylose into the liquid. • Gelatinisation begins at 60°C and the liquid will thicken at about 80 85°C, but is not fully complete until the sauce has boiled - 100°C.

Questions - Homework • Why is it important to regularly stir a starch based sauce? • At what temperature do the starch granules begin to absorb liquid. • What is the function of amylose in the making of a starch based sauce? • At what point in the process is gelatinisation fully completed. • What is a roux sauce and give an example of when you may use a roux?