KS3 Food Science
What's covered
Key facts
Cooking Methods
Brief blanching followed by cooling preserves the bright colour of green vegetables (peas, beans) by inactivating enzymes before they can dull the chlorophyll.
Enzymic Browning
Blanching in boiling water then cooling stops enzymic action because the brief heat denatures the enzymes and the cool water halts further cooking.
Fats in Cooking
In cake making, the role of fat creamed with sugar is aeration — adding air to lighten texture.
Heat Transfer
Boiling transfers heat mainly by convection as hot water rises and cooler water sinks, circulating around the food.
Proteins in Cooking
When a denatured protein then sets solid, the process is called coagulation.
Raising Agents
Baking powder produces carbon dioxide (CO₂) to make cakes rise.
Starch in Cooking
Starch is broken down in the mouth by the enzyme amylase.
Sugar in Cooking
Both caramelisation and the Maillard reaction produce brown colours in cooked food.
Why Food is Cooked
Cooking can make food easier to digest because heat softens fibres and breaks down cell structures.
Cooking Methods
Boiling vegetables loses vitamin C largely because it dissolves into the cooking water, which is then discarded.
Sample questions
A taste of the 97 questions in this topic, answers marked. Sign up to practise the full set with spaced repetition.
Why does boiling vegetables reduce their vitamin C content?
- •boiling breaks down fibre which binds vitamin C in cells
- •high temperatures destroy all nutrients in the vegetable
- ✓vitamin C dissolves into the water and is then discarded
- •vitamin C reacts with oxygen in the water, becoming inactive
What triggers enzymic browning in fruit and vegetables?
- •bacteria on the knife contaminate the cut surface
- ✓enzymes in the cut surface react with oxygen in the air
- •heat causes sugars in the fruit to caramelise on the surface
- •water escaping from the cut cells dries out the surface
What is the role of fat in shortcrust pastry?
- •it absorbs water and binds all the ingredients together
- ✓it coats flour particles and prevents gluten developing, creating a crumbly texture
- •it dissolves the sugar and creates a sweet, crisp outer layer
- •it provides the raising agent that makes the pastry rise in the oven
Which cooking method uses infrared radiation to transfer heat?
- •boiling
- ✓grilling
- •poaching
- •steaming
Which is an example of protein coagulation in cooking?
- ✓egg white turning solid when heated
- •fat melting when heated in a pan
- •starch thickening a sauce when heated in liquid
- •sugar dissolving when stirred into warm liquid
What three conditions does yeast need to grow and produce carbon dioxide?
- •cold temperature, moisture, and starch
- •light, oxygen, glucose, and warmth
- •warmth, fat, and a small amount of salt
- ✓warmth, moisture, and a food source such as sugar
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