GCSE Food Science: Key Concepts in Heat Transfer, Proteins, Carbohydrates, and Emulsions

Conduction

Heat through solids (frying pan → food)

Convection

Heat through liquids/gases (boiling, oven)

Radiation

Heat waves (grill, toaster)

Microwave

Excites water molecules

Denaturation

Protein structure changes (heat, acid, whisking)

Coagulation

Protein sets & firms (scrambled eggs, custard)

Gelatinisation

Starch + water + heat → thick sauce

Dextrinisation

Dry heat → browning (toast)

Caramelisation

Sugar → brown & sweet flavour

Smoke point

Temp where fat breaks down

Biological raising agents

Yeast → CO₂ (bread)

Chemical raising agents

Baking powder/soda → CO₂

Physical raising agents

Air/steam expands (whisked eggs)

Emulsions

Oil + water + emulsifier (egg yolk/lecithin)

Enzymic Browning

Oxygen + enzymes → brown fruit (apple, banana)

Preventing Enzymic Browning

Lemon juice, water, fridge, cook

Gluten

Forms when flour + water → elasticity

Kneading

Strengthens gluten; too much → tough