Infusing

The liquid decides what you extract

Water

Dissolves sugars, acids, salts and some aromatics. Tea, stock, court bouillon, a herb tisane.

Milk and cream

Both water and fat, so it extracts the widest range. Bay in béchamel, vanilla in custard, cardamom in a rice pudding.

Oil and butter

Fat-soluble compounds only, and a great many aromatics are fat-soluble. Chilli oil, garlic butter, herb oils.

Alcohol

Dissolves both water- and fat-soluble compounds, and extracts things neither can. Vanilla extract, sloe gin, limoncello, bitters.

Vinegar

Acidic extraction, and it preserves. Raspberry vinegar, tarragon vinegar, chilli vinegar.

Sugar syrup

Extracts and preserves at once. Cordials and syrups.

Hot against cold

• Hot is faster and coarser. Heat speeds extraction and pulls out more, including bitter compounds and tannins. Minutes rather than days.
• Cold is slower and cleaner. Cold-brew coffee, cold-steeped tea and cold-infused cordials are less bitter and more aromatic because heat never drove the volatiles off.
• Volatile aromatics survive cold infusion and are largely lost to hot. This is why rose and elderflower cordials are made warm rather than boiled.
• Tannins and bitterness come out with heat, which is why over-brewed tea is bitter and cold brew is not.
• Fat infusions need warmth to be practical, and gentle warmth is enough.
• Alcohol infusions work cold and simply take weeks.
• Some things need heat — hard spices, roots and barks give up very little cold.

Doing it well

1. Break the surface. Bruise, crush, slice or grate — extraction happens at the surface, so more surface means faster and fuller infusion.
2. Choose the liquid to match what you want out of it.
3. Warm rather than boil, for anything aromatic. Boiling drives off the volatiles you are trying to capture.
4. Cover the vessel. Aromatics escape with the steam otherwise.
5. Taste as you go. Infusion is not a fixed time — it is a process you stop when it is right.
6. Strain before it goes bitter. Almost everything over-infuses eventually.
7. Strain through muslin for clarity, or a sieve if it does not matter.

Common infusions worth knowing

• Bay and onion in milk for a béchamel or a bread sauce. Warm, covered, thirty minutes, strained.
• Vanilla in cream for custard and ice cream. Split the pod and warm gently.
• Garlic and chilli in oil, which raises food-safety questions about storing infused oils — follow Food Standards Agency guidance.
• Saffron in warm water or milk for twenty minutes before it goes into a dish. Never added dry.
• Lemongrass and ginger in stock, bruised and removed.
• Coffee or tea in cream for a set dessert.
• Herbs in vinegar, which keeps for a year and is a good use of a glut.
• Citrus zest in sugar, which is a dry infusion and works by the same principle.

Common questions