Function of Sugar

Function and purpose of Sugar:

• sweetens drinks and food e.g. tea and coffee
• improve or changes the flavour by removing the sour taste, e.g. in tomato products
• speeds up fermentation when yeast releases carbon dioxide in bread making
• adds colour. When sugar is heated it turns golden brown. This is called caramelisation
• stabilise whisked mixtures, e.g. meringue because it strengthens the foam
• keeps food products moist and helps extend shelf life
• aerates food products. When sugar is beaten with butter or eggs it helps trap air to make cakes light
• bulking agent. Gives the characteristic texture to food, e.g. ice cream and cake
• preserves food. In large quantities it creates unsuitable condition for micro organisms (bacteria, yeasts and moulds) to grow, e.g. in jam and chutneys

Function and purpose of Starch:

Bulking agent:

• Flour is often the main ingredient in many food products and we call this the bulk ingredient. The starch forms the mian structure of the product. Example include: biscuits, cakes and pastry

Thickening agent:    

• Raw starch tastes floury and therfore needs to be cooked, for example plain flour. When starch is heated in a liquid, the walls of the starch become soft and allow liquid to pass slowly through them. This make the granules swell until they burst. This process is called gelatinisation and is explained in more detail below.

Gelatinisation: 

• Starch particle do not dissolve in liquid. Instead they form something called a suspenion
• If the liquid is not stirred, the starch granules sink to the bottom. stick together and start to form lumps.
• When heated, at 60 degrees, the starch granules begin to absorb the liquid and swell
• At 80 degrees, the particle will have aborbed about five times their volume of water until they burst open and releae starch, thickening the liquid. The mixture becomes thick and viscous. This process is gelanisation.
• Gelanisation is complete when the liquid reaches boiling point, 100 degrees.
• When the sauce cools, it goe even thicker, setting into a gel.