Rendering fat

What is happening

Animal fat is held in cells within connective tissue. Heat melts the fat and breaks down enough of the tissue for it to run out. What is left behind is the tissue itself, which browns and crisps — scratchings, cracklings, gribenes, whatever the tradition calls them.

The reason it must be slow is that fat scorches easily and scorched fat tastes of scorched fat permanently. Rendered gently, it is clean, pale and neutral-to-savoury. Rendered fast, it is brown, bitter and smells of the pan.

On a piece of meat, rendering is what allows the skin to crisp: skin sitting on unrendered fat is being steamed from below, however hot the oven is.

Rendering a bag of fat into a jar

Ask a butcher for pork back fat, beef suet or a duck carcass. It is usually very cheap.

1. Cut the fat into small pieces, or mince it, or freeze it briefly and grate it. Smaller pieces render faster and more completely.
2. Put it in a heavy pan with a splash of water. The water stops it catching before any fat has run, and it boils off.
3. Set it over the lowest heat you can manage, or put it in a very low oven, which is easier to control.
4. Leave it alone. It will take one to three hours. Stir occasionally.
5. It is done when the liquid fat runs clear and the solid pieces have shrunk, browned and stopped bubbling.
6. Strain through muslin into clean jars while liquid. It sets pale and firm.
7. Keep the crisp solids. Salt them and eat them.

Rendering on the food itself

Pork skin for crackling

Score, dry, salt. Hot to start or hot to finish, and low in between so the fat renders before the skin sets.

Duck or chicken skin

Start skin side down in a cold pan and bring the heat up slowly. The fat renders gradually and the skin flattens.

Bacon and pancetta

Cold pan, low heat. Fast heat seizes the meat and leaves the fat unrendered.

A fatty joint in the oven

Score the fat cap so it can escape rather than sitting under the surface.

Mince and sausages

Fat renders into the pan and is usually poured off or kept.

The signal

The skin flattens and thins, and the pan fills with clear fat. Skin sitting proud over soft fat has not rendered.

What to do with what you collect

• Roast potatoes. Duck fat, goose fat and beef dripping are all better than oil for this and it is the main reason to bother.
• Pastry. Lard makes flakier shortcrust than butter, and hot-water crust for a pork pie requires it.
• Frying eggs, bread and black pudding.
• Confit, which needs a lot of fat and reuses it repeatedly.
• Refried beans and Mexican cooking, where lard is the traditional fat and a genuine flavour.
• Yorkshire puddings, where hot beef dripping is traditional.
• Straining and reusing. Strained rendered fat keeps well, and how long is a food-safety question for the Food Standards Agency.

Common questions