Effect of Heat on Food

Sugar dissolves, changes colour and caramelises to a brown colour.

Used to colour syrups.

Makes caramel.

Carbohydrate value is not lost unless the food is burnt.

Found in sucrose from sugar beet or sugar cane.

Solid fats melt to liquid, give off smoke and burn at high temperatures.

Fats have different melting temperatures.

Can be used for frying but those with higher melting points fry food better.

Fat is not changed in value unless burnt.

Butter, lard and margarine.

Oils - corn, sunflower, soya bean and olive oil.

Protein denatures, changes on heating and then coagulates (transforms to a solid mass) and sets.

Protein in eggs coagulate and set when heated and become solid.

Meat hardens.

Protein value is not lost unless the food is burnt.

Found in: eggs, cheese, milk, flour, meat, fish, beans and pulses.

Fibre softens when it is heated with liquid.

Cabbage is softened when it is cooked.

Dietary fibre remains undigestable after cooking.

Found in: cereals, fruit and vegetables.

Effect of heating

Fat-soluble vitamins are not affected by the cooking process.

Nutritional Changes

Fat-soluble vitamins are not lost in cooking.

Effect of heating

Vitamins B and C dissolve in water. High temperature cooking such as frying destroys water-soluble vitamins.

How is this used in the cooking process?

Vitamin C is easily lost when preparing and cooking vegetables. Avoid long cooking and keeping vegetables warm.

Nutritional Changes

Water-soluble vitamins are lost during cooking.

Vitamin C is lost is fruit and vegetables are stored for too long.

Effect of heating

Heating has little effect on minerals.

Nutritional Changes

There is little mineral loss during cooking.