Using gelatine to clear homebrew

Gelatine pulls yeast and haze out of suspension

Gelatine is a protein made from animal collagen. Dissolved in warm water, its long molecules carry a positive charge. Yeast cells and the protein and polyphenol particles that make chill haze carry a negative charge. When gelatine goes into the beer, it binds to them. The clumps grow heavy enough to sink to the bottom of the fermenter or keg.

This is a cold side fining. It works after fermentation, unlike Irish moss or kettle finings, which go into the boil and target proteins in the hot wort. The two do different jobs and many brewers use both. Our guide to Irish moss and kettle finings covers the boil side.

The beer has to be cold first

Gelatine works far better on cold beer. Chill haze only forms when beer is cold. If you add gelatine to warm beer, the haze particles are still dissolved and the gelatine has nothing to grab. Bring the beer down to 0 to 4 °C first and hold it there for at least a day so the haze forms. Then add the gelatine.

That makes a fridge essential. In much of India a fermenter left in a corner of the kitchen will sit at 25 to 30 °C for most of the year. Gelatine at that temperature drops some yeast but leaves the beer hazy once you chill a glass. If you cold crash, our guide to cold crashing without suck-back shows how to do it without drawing air into the fermenter.

The dose and method for 20 litres

Use plain, unflavoured powdered gelatine from a grocery or baking shop. Avoid flavoured jelly crystals, which carry sugar, colour and acid. The usual homebrew dose is about half to one level teaspoon, roughly 1.5 to 3 g, for a 20 litre batch.

1. Sanitise a small heatproof cup or jug.
2. Sprinkle the gelatine over about 100 to 150 ml of cool water. Let it bloom for 10 to 15 minutes.
3. Warm it gently to around 65 to 70 °C, stirring until it is fully clear. A microwave in short bursts works. Do not let it boil, because boiling breaks down the protein.
4. Pour the warm solution into the cold beer gently. Avoid splashing.
5. Leave the beer cold and undisturbed for 24 to 48 hours.

More is not better. A heavy dose can strip some body and hop aroma without making the beer any clearer.

Adding it without letting air in

The only awkward part is opening the fermenter. Cold beer has no active yeast to scavenge oxygen. Air you let in stays in the beer. Have the solution ready before you open the lid, pour it quickly and close up. If your fermenter has a port or you keg, adding gelatine through the keg lid then purging with carbon dioxide is cleaner.

Many homebrewers who keg add gelatine straight to the keg. It works the same way. The first pint or two will be cloudy as it pulls the sediment. After that the beer pours clear.

When to leave gelatine out

• Vegetarian or vegan drinkers. Gelatine is animal derived, usually from pork or beef. Many of your friends will want to know. In India that matters to a lot of people, so label any beer fined with gelatine. Plant-based finings exist if you need an alternative.
• Styles meant to be hazy. Hefeweizen, witbier and hazy IPA are cloudy on purpose. Fining them strips both the haze and some flavour.
• Heavily dry hopped beers. Gelatine can pull some hop compounds along with the haze. Use a lighter dose or none.

Bottle conditioning still works

Brewers often worry that fining removes all the yeast and the bottles will not carbonate. In practice enough yeast stays in suspension to carbonate bottles after gelatine fining. It may take a few days longer, so give bottles three weeks at 20 to 24 °C before judging them. The sediment in each bottle will be firmer and thinner, which makes pouring clean easier.

Clarity is not a quality score on its own. A clear beer can still be stale or flawed. Knowing why a beer is hazy matters more than masking it. Starch haze, a bacterial infection and simple yeast haze look similar in the glass and need different fixes. That is where a structured course earns its keep.

Your first step: buy a packet of plain gelatine and keep it with your brewing kit. On your next batch, chill the beer for a day then add half a teaspoon dissolved as above. Compare a glass after 48 hours.