The science of food
What's covered
Key facts
Carbohydrates
Caramelisation and Maillard browning are not the same reaction.
Fats
Aerating fat by creaming it with sugar adds air to a cake mixture.
Fruit and vegetables
Blanching denatures the browning enzyme with heat, so blanched fruit and vegetables can be frozen without going brown or developing off-flavours.
Functional and chemical properties
Aeration is the process of trapping air in a mixture to lighten its texture (whisking, sifting, creaming, folding).
Heat transfer
Conduction is heat transfer through direct contact between molecules; it is the dominant mechanism in solids.
Microorganisms and spoilage
Bacteria reproduce by binary fission: one cell splits into two.
Proteins
Coagulation is the step in which denatured proteins aggregate and set solid; for egg white this is what makes it turn opaque and firm on frying.
Raising agents
Baking powder is a chemical raising agent.
Carbohydrates
Dextrinisation is the process where starch turns brown when dry-heated.
Fats
Creaming butter and sugar creates air bubbles in the mixture.
Practice questions with answers
A taste of the 95 questions in this topic, answers marked. Sign up to practise the full set with spaced repetition.
What happens to starch granules when heated in liquid?
- •they evaporate away into the air
- •they shrink and harden into lumps
- ✓they swell and burst, thickening the liquid
- •they turn into fat globules in the pan
What does creaming butter and sugar create?
- •a glaze
- •a syrup
- ✓air bubbles
- •an emulsion
Why does adding lemon juice stop a sliced apple from browning?
- •it adds water
- •it seals it with sugar
- •it sterilises the apple
- ✓vitamin C is an antioxidant
What is a blended sauce, such as a cornflour sauce, made from?
- •Egg yolk whisked with oil
- •Mayonnaise thinned with milk
- ✓Starch and liquid, with no fat
- •Tomatoes blended with herbs
Meatballs are browned in a hot frying pan. How does heat pass from the pan base into the meatballs?
- ✓Conduction
- •Convection
- •Evaporation
- •Radiation
What does storing food in a fridge do to bacteria?
- •Kills them all
- •Makes them harmless
- •Removes them fully
- ✓Slows their growth
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