This is a topic I've brushed on before, but I get plenty of questions about it. So I decided to do a full post dedicated to my favorite fining agent: gelatin. If you ask people their feelings on using gelatin to fine beer, you'll get a number of different opinions. Personally, I find it invaluable to clear my beer quickly. Fining one's beer with gelatin isn't difficult, but it does require a few specific steps. Here's the process I've had success with.
Fermenter or Keg
The first question to ask, is: What state should our beer be in when we add the gelatin? There are two methods, and they both work equally well. You can fine with gelatin in either a fermenter (primary or secondary), or directly in the serving keg. I typically opt for the later. Although, in either case, you want the beer to be cold, and I mean ICE cold. The colder the beer is, the more haze-forming particulate will form. The more haze-forming particulate that forms, the more particulate the gelatin can fine out. I've heard people have used gelatin with some success at cellar temps (50-55F), but I've only had it work well when the beer was at serving temp (32-40F).
Which Gelatin to Buy?
Obviously, you shouldn't buy cherry jello; you're looking for unflavored gelatin. Knox is a popular brand that most supermarkets carry, but I find the store-brand works just as well. Most LHBS also carry gelatin, but they tend to include a hefty markup on the price. The specifics don't matter much, so long as you buy unflavored gelatin, you'll be fine.
With your beer chilled down and gelatin in hand, let's get to the process of fining your beer
- Get a microwave-safe glass cup. I like to use a pyrex measuring cup. Measure out 2/3 cup cold water. Any water will work, but I wouldn't use tap water if it tastes like crap.
- Add one teaspoon of gelatin, and stir the solution. I like to use using my thermometer probe, so I can check the temperature at the same time.
- Place the water/gelatin mixture in the microwave, and begin to heat it 15-30 seconds at a time, stopping to stir the solution and check the temperature. As it heats up, you'll notice the gelatin will begin to dissolve.
- The goal is to heat the gelatin to 150F, but not much over. If it climbs to 155 or so, that's fine, but I'd be hesitant to go much over 170F. We're not trying to make jello, rather just trying to pasteurize the solution.
- Give the mixture one last stir, and dump it straight into your beer. Gently swirl the fermenter or keg, and return it to your fridge or kegerator for 24-48 hours.
- If you used a keg, purge the headspace with CO2 to remove any oxygen that got mixed in.
Gelatin works rather quickly. It's extremely effective at dropping yeast out of solution, as well as lots of haze-forming particulates. I find that 48 hours later, the beer drops crystal clear. If you bottle your beer, rack the beer to a bottling bucket, and bottle away. Don't worry, there are still plenty of yeast in solution to carbonate the bottles.
If you keg, you'll have to draw off a couple very cloudy pints before the beer clears up. Gelatin literally drops yeast and particulates down to the bottom of the keg. Since the dip-tube draws from the bottom, that junk will be the first thing pulled from the keg. After a pint or two, it'll be smooth sailing until the keg kicks.
One Last Note
While gelatin does a fantastic job at quickly clearing beer, there's still no substitute (unless you filter) for cold conditioning if you want your beer to truly sparkle. If I fine my beer with gelatin, and then leave it for a week in the kegerator, I can obtain commercial level clarity.
That wraps up the easy, but detailed process of using gelatin as a fining agent. Cheers to clear beer!