What jobs do ingredients do in a recipe, and how does understanding them help develop food products?
The functional properties of ingredients in food, including aeration, binding, bulking, coating, dextrinisation, emulsification, gelatinisation, shortening and thickening, and how they are used when developing food products.
An SQA National 5 Health and Food Technology answer on the functional properties of ingredients, covering aeration, binding, bulking, coating, dextrinisation, emulsification, gelatinisation, shortening and thickening and their use in developing food products.
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What this dot point is asking
The SQA wants you to know what a functional property is, name the main functional properties of ingredients, explain what each does, and apply them by saying how an ingredient behaves in a particular dish.
What a functional property is
Understanding functional properties is the heart of food product development: it explains why a recipe works and lets a developer swap, add or change ingredients to get the texture, structure or appearance they want.
The main functional properties
Looking at the science behind three key ones
Gelatinisation and thickening both involve starch. When starch grains are heated in a liquid they absorb it, swell and burst, releasing starch that thickens the mixture. This is how flour or cornflour thickens a sauce, gravy or soup.
Shortening involves fat. When fat is rubbed into flour it coats the flour grains and stops them forming long gluten strands, giving a short, crumbly texture. This is why pastry made with enough fat is crumbly rather than tough.
Aeration involves trapping air. Whisking egg whites, creaming fat and sugar, or sieving flour all add air, which expands on heating to make a product rise and feel light.
Examples in context
Example 1. Developing a quiche. Eggs in a quiche show two properties at once: they set on cooking to bind the filling, and the pastry case relies on the shortening property of fat to stay crumbly. A developer chooses the egg-to-liquid ratio to get a firm but not rubbery set.
Example 2. A reduced-fat sauce. A developer making a lower-fat cheese sauce uses cornflour for gelatinisation to thicken it, so they can cut the amount of fat and flour from a traditional roux while still getting a smooth, thick sauce.
Try this
Q1. Name the functional property where starch grains swell and burst in hot liquid to thicken it. [1 mark]
- Cue. Gelatinisation.
Q2. State one functional property of eggs and give a dish that uses it. [1 mark]
- Cue. Aeration in a whisked sponge or meringue (also acceptable: binding in a burger, coating on fried fish, or emulsification in mayonnaise).
Exam-style practice questions
Practice questions written in the style of SQA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
SQA N5 style4 marksExplain the functional properties of eggs that make them useful in food products, giving an example dish for each property.Show worked answer →
A 4-mark answer needs two properties of eggs, each with an example, so plan two property marks and two example marks.
Property 1. Aeration. When eggs (especially egg whites) are whisked, they trap air to form a foam, which makes a product light. An example is a whisked sponge or a meringue.
Property 2. Binding. Beaten egg holds dry ingredients together so a mixture does not fall apart. An example is using egg to bind a burger or fishcake.
Other valid egg properties are coating (egg helps breadcrumbs stick to food before frying) and emulsification (egg yolk helps oil and water mix, as in mayonnaise). Markers reward each correct property and a sensible example. Naming a property with no example, or an example that does not match, loses marks.
SQA N5 style3 marksDescribe the functional property of gelatinisation and explain how it is used when making a sauce.Show worked answer →
This question rewards a clear definition of gelatinisation and its use.
Gelatinisation is when starch grains are heated in a liquid: they absorb the liquid, swell and burst, and the mixture thickens. It needs both heat and a liquid.
When making a sauce, a starch such as flour or cornflour is mixed with a liquid such as milk and heated while stirring. As the temperature rises the starch grains gelatinise, so the sauce thickens to the right consistency, for example a white sauce for a lasagne.
A further point that scores is that stirring keeps the sauce smooth and stops lumps forming as it thickens. Markers reward the swell-and-burst mechanism and the link to thickening a sauce.
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