Fat-washing spirits
Stir melted fat into a spirit, let it infuse, then freeze the fat solid and lift it off. The flavour stays behind, the grease does not.
Why it works
Much of what we taste as the flavour of butter, bacon, olive oil or toasted sesame comes from aroma compounds that dissolve far better in fat than in water. A spirit at 40% alcohol sits in between: ethanol is a good solvent for many of those same compounds, so when you mix warm fat and spirit and give them time, the aromas share themselves out between the two. Some move into the spirit and stay there.
The trick is getting the fat back out. Most fats are solid in the freezer, while a 40% spirit does not freeze until well below the −18 °C of a home freezer. Chill the jar and the fat sets into a hard layer on top, because it is lighter than the spirit. Lift it off, filter what is left, and you have a clear spirit that smells and tastes of the fat without the oily slick.
Not every trace of fat leaves. A small amount stays dissolved or held in tiny droplets, and that is what gives fat-washed spirits their slightly rounder, softer feel in the mouth. It also takes a little of the edge off hot, young spirits. Too much residual fat, though, reads as greasy and goes stale quickly, which is why the filtering matters.
The method rewards restraint. Fats with a loud flavour, like bacon, sesame or duck, need much less than butter. The aim is a spirit that still tastes of itself, with the fat sitting behind it as an accent, so it works in a cocktail rather than taking it over.
What you need
- Wide-mouthed jar or container: A wide surface gives a thin, broad disc of fat that lifts off cleanly; a 1-litre clip-top jar suits a 750 ml bottle.
- Small saucepan: For melting or browning the fat; use a light-coloured pan for brown butter so you can see the colour.
- Kitchen scale: Fat is measured by weight; small differences matter with strong fats like bacon.
- Fine sieve and cheesecloth: For the first pass, to catch flakes of fat and browned solids.
- Paper coffee filters and a funnel: The second, slow pass that removes the fine haze of fat; this is what makes the result clean.
- Clean bottle and labels: Write the fat, the spirit and the date on every bottle.
Step by step
Choose the spirit and the fat
Pick a spirit with enough character to stand up to the fat: a bourbon around 45%, an aged rum, a London dry gin. Weigh the fat using the table below. Start at the low end the first time; you can always wash a second batch and blend.
Tip: Work with a full 750 ml bottle. Smaller batches are fine, but you lose proportionally more spirit to the fat.
Melt or cook the fat
Melt butter, coconut oil or rendered fat gently until liquid. For brown butter, keep cooking over medium heat, swirling, until the milk solids turn hazelnut brown and it smells toasty, then take it off the heat at once. For bacon, fry it slowly and pour off the rendered fat. Let any hot fat cool for a few minutes until it is warm rather than sizzling.
Tip: Keep the browned milk solids from brown butter. They carry much of the flavour and are strained out later with everything else.
Combine away from the heat
Pour the spirit into the jar first, then the warm fat on top. Never add spirit to a pan on the hob: alcohol vapour catches easily and you lose aroma to evaporation. Close the lid and shake hard for 20–30 seconds so the fat breaks into small droplets with lots of surface.
Rest at room temperature
Leave the jar somewhere at normal room temperature for 4 hours to overnight, shaking it whenever you pass. Room temperature keeps the fat liquid and mobile, which is when the flavour moves. Butter and neutral oils like a longer rest; bacon and sesame can be ready in 2–4 hours.
Tip: Taste a spoonful at the halfway point. If it already tastes right, move on to freezing.
Freeze until the fat is solid
Put the jar in the freezer for at least 4 hours, ideally overnight. The fat floats up and sets into a hard cap. Animal fats and coconut oil set firmly; olive and sesame oil turn thick and waxy rather than rock-hard, so give them longer.
Tip: A fridge sets butter and coconut oil, but the freezer gives a firmer layer that breaks off in clean pieces.
Lift off the fat
Work straight from the freezer while the fat is cold. Pierce the cap with a spoon or knife, lift it out in pieces and set it aside. Pour the spirit through a sieve lined with damp cheesecloth to catch the flakes and any browned solids.
Tip: The leftover fat has soaked up some spirit and flavour. Bacon or butter fat is good for cooking, provided you do not use it near an open flame while it is still wet with alcohol.
Filter until clear
Pour the spirit through a paper coffee filter set in a funnel. It is slow, often an hour or more for a full bottle. Do not squeeze the cloth or press the filter: you push fat through. If it still looks hazy, chill it again and filter a second time.
Tip: Changing the filter when it slows to a drip saves time; fat clogs the pores.
Bottle, label and chill
Funnel the spirit into a clean bottle, label it with the fat, spirit and date, and keep it in the fridge. Expect to lose about 5–10% of the volume to the fat. Taste it neat and in a small cocktail before you plan a party around it.
Fats, spirits and what to make
| Fat | Spirit | Per 750 ml | Make |
|---|
| Brown butter | Bourbon or aged rum | 50–60 g | Old Fashioned, Hot Toddy |
| Unsalted butter | Rye or Cognac | 50–60 g | Sazerac, Sidecar |
| Bacon fat (smoked) | Bourbon | 30–45 g | Benton's Old Fashioned |
| Extra virgin olive oil | Gin or vodka | 40–60 ml | Martini, Gibson |
| Coconut oil (virgin) | White or aged rum | 40–60 g | Daiquiri, Piña Colada |
| Toasted sesame oil | Japanese whisky | 10–15 ml | Highball, Old Fashioned |
| Duck fat | Armagnac or bourbon | 30–45 g | Old Fashioned, Manhattan |
| Peanut or almond butter | Bourbon or aged rum | 60–90 g | Old Fashioned, flip-style drinks |
Timeline
| Stage | Time | What is happening |
|---|
| Melt or brown the fat | 5–15 min | Fat turns liquid; browning creates new nutty, toasty aromas. |
| Combine and shake | 1 min | Fat breaks into droplets, giving a large surface for flavour to cross. |
| Rest at room temperature | 4 h – overnight | Aroma compounds move from the fat into the spirit. |
| Freeze | 4 h – overnight | Fat rises and sets; the spirit stays liquid. |
| Remove fat and sieve | 10 min | The solid cap and coarse flakes come out. |
| Coffee-filter | 1–2 h | The fine haze of fat is caught. |
| Rest in the fridge | 1 day (optional) | Flavours settle and any last haze can be filtered again. |
Troubleshooting
It tastes greasy or looks cloudy
Fine droplets of fat got through, usually because the spirit warmed up during filtering or the cloth was squeezed. Chill the bottle in the freezer for an hour or two and filter it again through a fresh coffee filter. A faint haze that disappears at room temperature is normal with olive oil.
Hardly any flavour came through
Too little fat, too short a rest, or a fat with little flavour to give. Use the upper end of the range, rest it overnight and shake it more often. For butter, browning makes a much bigger difference than adding more.
It tastes stale, waxy or like old crayons
That is rancidity: fat oxidising, either because the fat was old or the finished spirit sat too long with traces of fat in it. You cannot fix it. Next time use fresh fat, filter carefully, keep the bottle in the fridge and drink it within a few weeks.
The fat won't separate
Some oils, especially sesame and certain olive oils, stay soft even in the freezer. Give it a full night, then pour the spirit off carefully from underneath, or ladle the thick layer away before filtering. Leave the jar undisturbed while it freezes so the fat collects in one layer.
The bacon version tastes like smoke and salt, not bourbon
Too much bacon fat. Blend it with plain bourbon, starting at one part washed to one part plain, until the spirit comes back. Next time use around 30 g.
Bits of brown butter are in the bottle
The browned milk solids are fine and light, and some slip past a sieve. Run it through a coffee filter again. Left in, they can turn the spirit sour over time.
Fat, heat and allergens
A 40% spirit is too strong for most bacteria, but traces of fat and milk solids still spoil, so treat a fat-washed spirit more like a fresh ingredient than a bottle for the shelf.
- Strain and filter thoroughly; animal fat and milk solids left in the spirit are what go off.
- Keep it in the fridge, label it with the date, and use it within about three weeks. Throw it out if it smells rancid or sour.
- Never add spirit to a hot pan or pour it near a flame. Let fat cool before combining, and work away from the hob.
- Butter-washed spirits contain traces of dairy, and nut-butter versions traces of nuts. Tell guests, and label the bottle clearly.
- Bacon and duck fat make a spirit unsuitable for vegetarians, and bacon for anyone avoiding pork.
- As with any cocktail: not in pregnancy, not before driving, and one rich, strong drink goes a long way.
