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Science

Vegetable oils, emulsions and hydrogenation

Vegetable oils in cooking

Vegetable oils have higher boiling points than water. This means that foods can be cooked or fried at higher temperatures than they can be cooked or boiled in water. Food cooked in vegetable oils:

  • cook faster than if they were boiled
  • have different flavours than if they were boiled.

However, vegetable oils are a source of energy in the diet. Food cooked in vegetable oils releases more energy when it is eaten than food cooked in water. This can have an impact on our health. For example, people who eat a lot of fried food may become overweight.

Saturated and unsaturated fats and oils

The fatty acids in some vegetable oils are saturated: they only have single bonds between their carbon atoms. Saturated oils tend to be solid at room temperature, and are sometimes called vegetable fats instead of vegetable oils. Lard is an example of a saturated oil.

The fatty acids in some vegetable oils are unsaturated: they have double bonds between some of their carbon atoms. Unsaturated oils tend to be liquid at room temperature, and are useful for frying food. They can be divided into two categories:

  • monounsaturated fats have one double bond in each fatty acid
  • polyunsaturated fats have many double bonds.

Unsaturated fats are thought to be a healthier option in the diet than saturated fats.

Back to Plant oils and their uses index

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