Food science

Question 1

Give a step by step of gelatinisation.

Answer 1

• Starch is found in small granules and the starch molecules inside are made up of thousands of glucose molecules joined in long straight chains.
• when starch granules are added to cold water they sink
• When heated to 60 degrees the starch granules absorb the water and begin to swell
• in sauce making, this makes the sauce thicker because there is less room for starch granules to move around
• at 80 degrees starch granules are very swollen so start to burst, releasing starch molecules into the surrounding liquid
• the starch molecules form a 3D network that traps water molecules and stops them moving around as much
• at 100 degrees the sauce completely thickens
• as the sauce cools down the sauce forms a solid gel.

Question 2

what is an example of a chemical raising agents, how do they work and in what recipes are they used?

Answer 2

• baking soda or bicarbonate of soda
• when heated or mixed with acidic ingredients carbon dioxide is produced. These CO2 bubbles are releases they expand the mixture.
• used in strongly flavoured cakes

Question 3

what are examples of a biological raising agent, how do they work and in what recipes are they used?

Answer 3

• yeast
• when supplied with moisture, heat and time this will cause the process of fermentation where carbon dioxide and ethanol are released as products. This CO2 produced causes the bread dough to expand and rise.
• used in bread making