Nutritional properties

Starch

• thickens a liquid by forming a suspensionsuspension: A mixture of two substances, one of which is finely divided throughout the other. such as a sauce
• forms a gel when the suspension is heated, like adding cornflour to a custard powder and milk mix

Sugar

• flavours by sweetening
• colours by caramelising [caramelise: Turn to caramel - a brown liquid which sugar becomes when heated to the point where all the water has been driven off and the sugar begins to burn. ] when heated
• aerates [aerate: Aerating mixes air into a material. ] when beaten with a fat such as in a cake mix

Proteins

• can coagulate which is when a liquid becomes firmer, for example when an egg is heated
• can aerate a mixture, like whisking egg whites in a meringue mix

Fats

• shortens pastry (makes it more crumbly) by making it less stretchy
• can act as an emulsifying agentemulsifying agent: A substance that helps two liquids (eg oil and water) stay mixed together. to stop two liquids from separating
• moistens a baked mixture such as a cake