What are fats, oils and sugars used for in cooking, what do they do to the diet, and what are their working characteristics?
Butter, oils, margarine, sugar and syrup as a food commodity group: their value and risks in the diet, the main types, working characteristics such as shortening, aeration and caramelisation, and storage.
A focused answer to the WJEC Food Preparation and Nutrition commodity group on fats, oils and sugars, covering their value and the health risks of eating too much, the main types, their working characteristics such as shortening, aeration and caramelisation, and storage.
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What this dot point is asking
You need to know what fats, oils and sugars provide and the health risks of eating too much, the main types, how they behave in cooking (their working characteristics), and how to store them.
What this group gives us, and the risks
Fats and sugars are concentrated sources of energy: fat gives about 9 kcal per gram and sugar about 3.75 kcal per gram. Fats also:
- carry the fat-soluble vitamins A, D, E and K,
- provide essential fatty acids the body cannot make,
- add flavour and a feeling of fullness.
Sugar provides quick-release energy but few other nutrients (they are sometimes called "empty calories").
This group is the small tip of the Eatwell Guide, eaten in small amounts, because:
- too much saturated fat raises blood cholesterol and the risk of heart disease,
- too much sugar causes tooth decay, weight gain and type 2 diabetes.
The main types
- Saturated fats (solid at room temperature): butter, lard and the fat in meat and dairy.
- Unsaturated fats and oils (usually liquid): olive, sunflower and rapeseed oil; these are the healthier choice.
- Margarine and spreads: made mainly from vegetable oils, often lower in saturated fat than butter.
- Sugars: white and brown sugar, plus syrups such as golden syrup and honey.
Working characteristics of fat
- Shortening
- Fat coats flour particles, stops long gluten strands forming, and gives a short, crumbly texture (shortcrust pastry, shortbread).
- Aeration
- When fat and sugar are creamed together, tiny air bubbles are trapped, helping cakes rise and giving a light texture (Victoria sponge).
- Plasticity
- Fats soften over a range of temperatures, so they can be spread and rubbed in.
Adding flavour, colour and moisture, and frying as a method of heat transfer.
Working characteristics of sugar
Sweetness and flavour, and balancing acidity.
Caramelisation. When heated above about 160 degrees Celsius, sugar melts and browns, developing a caramel colour and flavour (toffee, creme caramel).
Aeration when creamed with fat, and stabilising whisked egg foams in meringues.
Preservation. A high sugar concentration helps preserve foods such as jam, as it stops microbes growing.
Storing fats and sugars
- Fats and oils: keep cool and covered, away from light and air, because exposure makes them go rancid (off-flavour). Refrigerate butter and spreads; keep oils in a cool cupboard.
- Sugar and syrup: keep dry and sealed; sugar keeps almost indefinitely if it stays dry, but absorbs moisture and hardens if left open.
Exam-style practice questions
Practice questions written in the style of WJEC exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
WJEC style4 marksExplain two working characteristics (functional properties) of fat in baking, using an example for each.Show worked answer →
A 4-mark question. Award marks for two correctly explained properties with examples.
Shortening: fat coats the flour particles and stops long gluten strands forming, giving a short, crumbly texture, for example in shortcrust pastry and shortbread. Aeration: when fat and sugar are creamed together, air is trapped in the mixture, which helps a cake rise and gives a light texture, for example in a Victoria sponge. Other valid properties include adding flavour and colour, helping foods stay moist (extending shelf life), and frying as a method of heat transfer.
A top answer names each property, explains briefly how the fat behaves, and gives a correct example. Reward precise terms: shortening, aeration, plasticity.
WJEC style3 marksDescribe what happens when sugar is heated to make caramel, and give one use of caramel.Show worked answer →
A 3-mark question on caramelisation.
When sugar is heated, it melts and then begins to brown and change flavour at about 160 degrees Celsius and above, turning into a golden then dark caramel. This is caramelisation. The caramel has a sweet, slightly bitter flavour and a brown colour, and is used to make toffee and praline, to coat a creme caramel, or to add colour and flavour to sauces and desserts.
Markers reward: sugar melts then browns when heated to a high temperature; this is caramelisation and changes the colour and flavour; and a correct use such as toffee, creme caramel or a sauce.
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Sources & how we know this
- WJEC Eduqas GCSE Food Preparation and Nutrition specification (from 2016) — WJEC Eduqas (2016)