3.2.2

Fats & Oils

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Changing Properties - Fats and Oils

We can use fats and oils for different effects when we're cooking.

Aeration

Aeration

  • Aeration involves getting air into something.
  • We trap air in mixtures when we beat fats with sugar (known as creaming).
  • The added air lightens the mixture and gives it a fluffy texture.
  • Aeration causes cakes to turn out spongy and light when they're cooked.
  • We can use different methods to aerate foods, including beating or whisking.
Shortening

Shortening

  • Flour particles gain a waterproof layer when they're covered in fat. We can cover particles in fat by rubbing fat into flour.
  • We might choose to do this if we want to form baked goods with firm textures (i.e. cakes, biscuits or shortbread). This is because the coating stops long gluten molecules from forming when we add water to flour. The dough doesn't develop an elastic (stretchy) texture.
  • We use shortening to form pies and tarts because we want the base to be solid and not rise.
  • Shortening fats don't contain any water - they are made of fat only. This prevents gluten from forming.
Plasticity

Plasticity

  • If something has plasticity, it can be spread and moulded.
  • We can spread and mould fats because they are made up of different triglycerides that each have different melting points. This means fats don't melt at a set temperature but soften gradually across different temperatures.
  • Fats with more plasticity are easier to spread.
  • Fats with more unsaturated fatty acids have more plasticity than those with less and are easier to spread.
  • Plasticity is useful in everyday cooking. For example:
    • Spreading peanut butter, aioli or butter on toast.
    • Making cream cheese and smoked salmon sandwiches.
    • Icing cupcakes with buttercream.
'Easy to spread'

'Easy to spread'

  • You'll see some vegetable fat spreads labelled as 'easy to spread'.
  • These spreads are made up of triglycerides that melt at low temperatures (e.g. room temperature) so they're spreadable once they're out of the fridge.

Changing Properties - Fats and Oils

We can use fats and oils for different effects when we're cooking.

Emulisification

Emulisification

  • When we shake watery and oily liquids together, we create emulsions. Droplets from one of the liquids disperse throughout the other liquid.
  • We either create oil-in-water emulsions, like milk and vinaigrette, or water-in-oil emulsions, like butter and margarine.
  • We need to keep stirring or shaking the oily water so that the emulsions don't separate - they do this because oil and water don't naturally mix together. We can also use an emulsifier.
Emulsifier

Emulsifier

  • Emulsifiers are dual-ended molecules. They have a:
    • Hydrophilic end (water-loving) - bonds with water molecules.
    • Hydrophobic end (water-hating) - bonds with oil molecules.
  • The emulsifier keeps the water and oil together in what's called a stable emulsion. This means they don't separate.
Lecithin

Lecithin

  • Lecithin is a natural emulsifier found in egg yolks and soya.
    • It's commonly used in foods, like mayonnaise, which is made up of oil, vinegar and egg yolk in a stable emulsion.
Sauces and salad dressings

Sauces and salad dressings

  • Mayonnaise and hollandaise sauce are examples of emulsion sauces.
  • Vinaigrette is an example of an emulsion salad dressing.
  • You must add liquid and emulsifier before you add oil or fat when you're creating an oil-in-water emulsion. You must add the fat or oil very slowly and stir continuously as you add.
Recipe for hollandaise sauce

Recipe for hollandaise sauce

  • Place butter in a pan and melt.
  • Place lemon juice and egg yolks into a mixing bowl and stir.
  • Place the mixing bowl over simmering water to heat the mixture gently.
  • Slowly pour the melted butter into the mixing bowl, whisking continuously.
  • Whisk until the mixture is smoothly mixed.
Jump to other topics
1

Food Preparation Skills

1.1

Food Preparation Skills

1.1.1General Practical Skills1.1.2Knife Skills1.1.3Preparing Fruit, Vegetables & Using Equipment1.1.4Cooking Methods: Prepare, Shape & Combine1.1.5Sauce Making, Tenderising & Marinating1.1.6Dough & Pastry1.1.7Shaping & Finishing Dough1.1.8Raising Agents & Mixtures1.1.9End of Topic Test - Food Preparation Skills 1
2

Food, Nutrition & Health

2.1

Macronutrients

2.1.1Proteins2.1.2Proteins 22.1.3Fats2.1.4Carbohydrates2.1.5Carbohydrates 2
2.2

Micronutrients

2.2.1Fat-Soluble Vitamins2.2.2Water-Soluble Vitamins2.2.3Minerals & Water2.2.4Minerals & Water 22.2.5End of Topic Test - Macro & Micronutrients
2.3

Nutritional Needs & Health

2.3.1Informed Choices for a Balanced Diet2.3.2Informed Choices for a Balanced Diet 22.3.3Energy Needs2.3.4Nutritional Analysis2.3.5Diet Modifications2.3.6Diet-Related Problems2.3.7Diet-Related Problems 22.3.8End of Topic Test - Nutritional Needs & Health
3

Food Science

3.1

Cooking of Food & Heat Transfer

3.1.1Reasons for Cooking & Heat Transfer3.1.2Water-Based Cooking Methods3.1.3Fat-Based Cooking Methods3.1.4Dry Cooking Methods3.1.5Dry Cooking Methods 2
3.2

Functional & Chemical Properties of Food

3.2.1Proteins & Carbohydrates3.2.2Fats & Oils3.2.3Raising Agents3.2.4End of Topic Test - Food Science
4

Food Safety

4.1

Food Spoilage & Contamination

4.1.1Microorganisms & Signs of Food Spoilage4.1.2Enzymes & Signs of Food Spoilage4.1.3Food Poisoning4.1.4Bacterial Contamination4.1.5Microorganisms in Food Production
4.2

Principles of Food Safety

4.2.1Temperature Control4.2.2Ambient Foods & Food Labels4.2.3Preparing, Cooking & Serving Food4.2.4End of Topic Test - Food Safety
5

Food Choice

5.1

Factors Affecting Food Choice

5.1.1Factors Which Influence Food Choice5.1.2Food Choices5.1.3Religious Food Choices5.1.4Food Labels5.1.5Mandatory Food Labels5.1.6Optional Food Labels5.1.7Marketing Influences5.1.8End of Topic Test - Food Choice
5.2

British & International Cuisines

5.2.1British Cuisine5.2.2Japanese Cuisine5.2.3Japanese Ingredients & Dishes5.2.4Spanish Cuisine5.2.5Spanish Ingredients & Dishes
5.3

Sensory Evaluation

5.3.1Taste Receptors & Olfactory Systems5.3.2Sensory Testing Methods5.3.3Sensory Testing Methods 25.3.4End of Topic Test - Cuisines & Senses
6

Food Provenance

6.1

Environmental Impact & Sustainability of Food

6.1.1Food Sources - Intensive & Organic Farming6.1.2Food Sources - Genetically Modified Crops6.1.3Food Sources - Reared Food6.1.4Food Sources - Caught Food6.1.5Food & The Environment6.1.6Food & The Environment 26.1.7Sustainability of Food6.1.8Sustainability of Food 26.1.9End of Topic Test - Environmental Impacts
6.2

Food Processing & Production

6.2.1Primary Food Processing6.2.2Primary Food Processing 26.2.3Secondary Food Processing6.2.4Fortification6.2.5Additives6.2.6End of Topic Test - Food Processing & Production

Practice questions on Fats & Oils

Can you answer these? Test yourself with free interactive practice on Seneca — used by over 10 million students.

  1. 1
    Which of the following is true of fat plasticity?True / false
  2. 2
    What is the name of the process of beating fats with sugar?Multiple choice
  3. 3
    This emulsion is smooth, glossy, pale yellow, thick, and creamy. Which emulsion is this?Multiple choice
  4. 4
    Mayonnaise is an example of what type of emulsion?Multiple choice
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Proteins & Carbohydrates

Raising Agents