Earlier this month we talked about the easiest of the many fining agents that can be used to clarify (or “fine”) your homebrew: Irish moss.  In the commercial brewing industry, particularly in the United Kingdom where cask ales are still produced in larger volume, the most common fining agent is Isinglass.  Irish moss works to remove proteins from the beer which may cloud it, and is added during the boil.  Isinglass is added to the beer as it goes into the secondary fermenter.  As you know, we recommend a two stage process as recommended in our guide.  As with all fining agents, this is not something a complete beginner should worry about.  Make some batches, get things working well and then play around with clearer beer.  Start with hazier styles where this is not a factor.  But back to the topic at hand.  When the Isinglass is in the secondary it helps contribute to the flocculation of the yeast the clumping helps it drop out of suspension in the beeer, yielding a clearer brew.  But what is it and how do you use it?

First lets say this is not a product for strict vegetarians or vegans.  And it’s controversial (what isn’t these days?) as some people feel adding an animal product to the process, even if it doesn’t end up in the final product, is a pollution of the beer.  But rest assured it has been used for centuries in producing clearer beer and it’s harmless.  Isinglass is basically the swim bladder of a fish.  Originally it was exclusively that of the Beluga Sturgeon, but in modern times it’s made from many different kinds of fish, largely tropical and sub-tropical.  It’s similar to gelatin, but with different amino acids that give it enough different chemical properties to work better than gelatin for this purpose.

Because this is an animal-derived product it’s more sensitive to temperature and acidity than other additives.  Generally it should be fairly fresh and refrigerated if possible.  Often it’s not refrigerated and it works just fine, but the reality is that the fresher it is kept the more effective it is.  As with everything else, there is no point worrying too much about it.  Just make sure it’s not too old and hasn’t been stored in the sun, etc.

It’s sold either as a “liquid” which is more like a jelly, or as a powder.  Really the liquid is easier to use as it’s ready to go as-is.  But in the event that you need to use the powder you need to boil about a pint (500 mL) of water to sanitize it, let it cool, then mix in the appropriate amount of powder for your batch.  The instructions on the package will tell you the exact amount.

So here’s what to do with it:

• At the coolest point in your fermentation process, usually just as you’re going to move to the secondary, you will add it to the fermenter (the secondary one).  You don’t want to significantly cool the beer after this as it can re-cloud from chilling.
• Put the Isinglass in the secondary fermenter before you start to siphon in the beer from the primary.
• Siphon the beer from the primary onto the Isinglass.  This will help it mix well into the batch.

That’s it!  Proceed as normal with the rest of the fermentation process.  When you move the beer from the fermenter to the bucket for bottling, the Isinglass will be left behind with the yeast sediment.  You will not be drinking fish bladders.

Are there any drawbacks?  The main drawback is that it can sometimes take a little longer for bottle conditioning when using Isinglass.  This is because you are leaving behind more yeast than you might otherwise and that means those that are left have to work harder and that takes longer.  This is a small difference, and the tradeoff is clearer beer.  It’s your call!