Fats and oils decide the flavour, texture and shelf life of everything from pastry to curry. This guide explains the difference between fats, oils and shortening, how hydrogenation works, what to look for in a baking fat or frying medium, and how to store them.
Fats and oils: what is the difference?
Fats are solid at room temperature and melt when heated. Kitchen examples are butter, ghee, margarine, lard, suet and vegetable shortening. Oils are liquid at room temperature and may solidify when chilled. Common cooking oils include groundnut (peanut), coconut, mustard, sesame, olive, sunflower and safflower oil.
Both are made of fatty acids. Fats generally contain more saturated fatty acids, and oils contain more unsaturated ones, which is why oils stay liquid.
What is shortening?
“Shortening” is a fat used in baking and confectionery. It coats flour particles and breaks up gluten strands, so the finished product is tender and crumbly, not tough and chewy; it “shortens” the gluten. That is why a shortcrust pastry or a biscuit breaks off short and melts in the mouth.
Hydrogenation: turning oil into fat
Hydrogenation is a process in which hydrogen is added to a liquid vegetable oil, under pressure and heat and in the presence of a catalyst (commonly nickel). The hydrogen reacts with unsaturated fatty acids, making the oil more saturated and so more solid. Stopping the process at different points produces fats of different hardness, from soft margarine to firm bakery shortening.
Health note: partial hydrogenation can create trans fats, which are linked to a higher risk of heart disease. Many countries, including India through its food regulator FSSAI, restrict industrially produced trans fat in oils and fats. Check the current regulation and the label of the product you buy.
What to look for in a shortening
- Creaming value: how much air the fat holds when creamed with sugar. More air gives more volume in cakes.
- Shortening value: how well it makes the product short and tender, important for biscuits and cookies.
- Stability: how well it resists going rancid; this affects shelf life.
- Consistency: firm for puff pastry, which needs a fat that can be rolled in layers, and softer for cakes.
- Water absorption and emulsifying ability: how well the fat blends with liquids to give a stable mixture.
How fat works in baking
Fat adds tenderness, flavour, richness and satiety. The type of fat and how it is mixed in affect the result. In shortcrust pastry, fat is rubbed into the flour. In flaky and puff pastry, it is layered in so that it melts and the steam lifts the layers. Bake at the right temperature: if the oven is too cool, the melted fat leaks out before the flour can absorb it, giving a hard, greasy product. Fat broken into fine particles by creaming is absorbed more easily than fat left in large lumps.
Fat as a frying medium
In frying, fat transfers heat to the food, adds flavour and texture, and adds calories. A good frying fat should have:
- A high smoke point (so it does not burn and smoke at frying temperature).
- Good stability (so it can be used repeatedly without quickly breaking down).
- Low moisture content.
- A neutral flavour (unless flavour is wanted, as with mustard oil in some dishes).
- A low congealing point (so it stays pourable and does not leave a waxy coating).
Kitchen tips: do not overheat oil, strain it after use, do not top up old oil with fresh oil indefinitely, and discard oil that is dark, foamy or smells off. Never leave a hot fryer unattended.
Choosing the right fat: quick guide
- Cakes and sponges: a fat that creams well and holds air, such as butter or cake margarine.
- Biscuits and shortcrust pastry: a fat with good shortening power, rubbed or creamed in.
- Puff and flaky pastry: a firm, plastic fat that stays in layers.
- Deep frying: a stable oil with a high smoke point and a neutral taste.
- Finishing and flavour: butter, ghee or a speciality oil such as sesame or olive oil.
Storage
- Keep fats and oils in clean, covered containers, away from heat and direct light.
- Keep them away from strong-smelling foods, since fats absorb odours.
- Store butter and similar fats in a refrigerator or cold room.
- Use stock on a first-in, first-out basis.
Common mistakes
- Using a soft fat where a firm one is needed, such as in puff pastry.
- Reusing frying oil too often.
- Storing oil near a heat source.
- Ignoring the label when choosing a fat for allergies, vegetarian or religious needs.
Related reading
Learn about cooking methods in Poaching, Boiling and Broiling, and about the structure of an egg, another key baking ingredient. All my kitchen notes are on the Hotel Management Notes hub. Chefs and bakers who want to move up can search kitchen jobs on Hospitality Vacancy.
Frequently asked questions
What is shortening?
A fat used in baking that makes products tender and crumbly by interfering with gluten formation.
Is ghee a fat or an oil?
Ghee is a fat. It is solid or semi-solid at normal room temperature in most weather.
What is hydrogenation?
A process that adds hydrogen to unsaturated oils to make them more solid.
What is a smoke point?
The temperature at which a fat starts to give off visible smoke and break down. A frying fat needs a smoke point above the temperature at which you fry.
Which fat is best for puff pastry?
One with a firm, plastic consistency that can be rolled in layers, such as butter or a bakery margarine made for pastry.
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About the author: Sumit Manwal is the founder of Hospitality Vacancy (since 2017) and has 20+ years of experience in hospitality. He helps hotels build reliable teams and helps professionals grow their careers. Contact: manwal@hospitalityvacancy.com | LinkedIn
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