Eisebeer is a rich dessert beer
Eisbier (Ice Beer) is a traditional method of making beer stronger by freezing it. Water freezes out as ice and the remaining beer is stronger because it has proportionately more alcohol left in it. This is a Northern European traditional method, which is equivalent to the American Apple Jack method of concentrating hard cider.
The method shown here is quite simple and doesn't use any fancy equipment. You can do it at home with a standard food freezer. In the UK, it is too warm to do this using natural winter cold, but if you live in a northern state like Minnesota or Ohio, you can do this outdoors in the winter too.
The resulting beer is an unusually rich and smooth malty brew. This one is based on a dark amber Bock type beer I made especially. I made it with a heavy malt and low hop content. The original batch was called Sheddage as it was brewed in my shed and was brewed to about 9% ABV (alcohol by volume).
The resulting eisbier I named Uber Sheddage and was probably somewhere between 15 and 20% ABV.
Obviously, this is not a beer to mess about with. At this strength, this is a tippling beer to be sipped and enjoyed, not a swigging beer!
Preparation - What you need to make eisbier
This is not a hard Instructable, but it is very rewarding. You will need
- to make a base beer, so I am assuming you are a brewer already (although you could apply this to a shop bought beer in principle)
- either a domestic food freezer capable of freezing to -15C (5F) or to be living in a damn cold part of the world like Iceland or Minnesota :)
- a soda stream if you want to add fizz to the finished beer
- a love of strong delicious beers
Step 1: Brewing the Initial Beer to Transform Into Eisbier
Start by making your favourite beer
Eisbier is a technique applied to an existing beer. So, first you need to make a base beer.
You should start with a type of beer you love. This is a personal thing. I like dark malty beers, but the first time you try this, I would suggest you try this with a type of beer you really like. The advantage of using a beer you know, is that you can more easily see the change it makes.
I won't attempt to describe how to brew beer here. The Internet has about a gazillion variations on this. I am assuming that you are used to brewing beer and have a favourite method. I tend to use malt extracts because I can't be bothered with malting grains, but that is a whole other discussion.
If you do like beer recipes, I have an instructable for a dark English ale here that is quite good.
Concentrating beer changes its balance
The eisbier method will concentrate the flavour, so you should consider how your original beer is balanced. If you like hoppy beers, you might want to reduce the initial hop content as this will get concentrated.
It is safer to dry hop it after converting to eisbier, rather than risk making a beer that is too hoppy then bitter when concentrated. The maltiness will also get deeper and stronger. This is great if you like heavy sweet beers, but if not, then use less strongly flavoured malts in the initial brew. I am a non-purist and will use raw sugar if needed, not just barley malt. Using some sugar is a good way to increase strength without making the flavour too rich.
To recap, the first step is make a beer you like and possibly change the balance a bit.
I personally love rich beers, so I made my original beer (Sheddage) with a lot of dark malt extract and made it strong (9% ABV).
Step 2: Freezing Your Base Beer
Once you have brewed your initial base beer, the next step is simply to freeze at about -15C (about 5F). This will form what looks like a solid block, but actually is a combination of solid water ice and liquid concentrated beer. This is the alcohol that does not freeze at this temperature combined with dissolved flavourings.
TIP - use a flexible container!
Ice expands as it freezes and can burst bottles, so you should use a container with a bit of flexibility in it. Here I'm using an empty 3 litre cider bottle here. I also did not fill it completely, to allow for expansion. You can test the temperature of the freezer using a thermometer. My freezer is about -16C
Once filled with my base beer I left the bottle it in the freezer for a day until it was frozen solid.
Step 3: Collecting the Eisbier From the Frozen Base Beer
Let it drip...
Once frozen, the rest is patience. You just take the cap off your bottle of frozen beer and turn it upside down so that the top is inside a separate container to catch the eisbier. Then you just let the concentrated beer drip out.
Here you can see the original frozen beer in its bottle upside down on top of a wider-mouthed Soda Stream bottle
It takes a few hours.
I have found that beating the bottle gently with a rolling pin helps break up the ice inside and release the eisbier.
After a while, you will be left with a whitish block of ice in the bottle and a container full of lovely rich eisbier - it is really just that simple. The leftover ice is really just very weak beer with most of its alcohol and flavour removed. It is not worth keeping.
How strong is this?
This method is not very scientific. I started with 3 litres (about 6 and a bit US pints or just over 5 UK pints) of my base beer. This had a strength 9% ABV. I obtained about 1 litre of resulting eisbier or one third of the original volume.
It is tempting to imagine that the eisbier would be three times stronger than the base beer, but it probably will never be, because the water starts to melt as well. The initial drips when you start will be very strong. The drips after several hours collecting will be much weaker as water starts seeping out as well as alcohol.
I believe my attempt here was probably about 1.5 to 2.5 times as strong, so something like 15% to 20% ABV. Assume it is very strong when drinking to be on the safe side. Sip, don't guzzle.
If you have access to alcohol testing equipment you could just measure it!
Step 4: Adding CO2 to Give a Head
With a head or not?
Normally you would bottle or cask condition your beer to produce a head and give it some fizz. Because you are converting a completed beer that has been concentrated to 15+% ABV, this isn't going to work. There will be very little yeast left in it to re-ferment and even if there was, it would be hard for most beer yeasts to ferment a beer with that much alcohol.
Of course, this is a dessert beer. It doesn't need to be fizzy, or have a head. It is still deliciously syrupy like a liquour.
Having said that, it is quite amusing to add a head, so that the finished eisbier looks and feels just like normal beer. When you serve it, it is a surprise to discover the intense richness and sweetness.
I do like a bit of fizz and so I use a Soda Stream to carbonate it. It works a treat. Just fill it up and zap it. You should chill the beer first, so it takes more CO2. A simple and very effective trick.
TIP - Leave it to stand for 10 minutes before removing from the Soda Stream or it can froth over.
Step 5: Before and After
And so, here it is...
On the right (confusingly) is Sheddage, my original strong dark beer (9% ABV) and on the left is Uber Sheddage, the lush eisbier (15-20% ABV) that was made from it, using this method. You can see how much darker it is.
The original beer Sheddage was lovely. The eisbier version was skull-blowingly strong, rich, liquorice-ey and even bloody lovelier!
That is all there is to it. It really is that simple and it is delicious.
If you try it, you should read the disclaimer in the next step before doing this :)
Step 6: Is This Safe?
There is some debate over whether concentrating beer in this way is safe to drink or legal. Here are some thoughts on this to help you decide.
Health risks - opinion is divided
On the safety, there are varying opinions of the health concerns about this method. I side with those who think it is mainly about the risks of drinking beer that is deceptively strong. You could accidentally drink too much alcohol, which is a risk in itself. As for chemical risks, the risk is that any dodgy chemicals that can be present in the original beer in trace amounts are concentrated when making eisbier. At best this is only three time stronger, so drinking one glass of eisbier is unlikely to be any worse than drinking 3 glasses of the original beer. Unlike distillation, this method does not use heat so there is no real risk of heat-induced chemical decomposition introducing dodgy chemicals.
For the chemical science of how freeze separation works best, this experiment featured in the Journal of the Institute of Brewing from 1947 gives some research findings about the process:
R. E., Gane, R. and Morris, T. N. (1947), THE CONCENTRATION OF BEER BY FREEZING. Jnl Institute Brewing, 53: 204–208. doi: 10.1002/j.2050-0416.1947.tb01328.x
Legality - opinion is also divided!
The legality of fractional freezing is a grey area. In the UK, it is assumed to be legal, but it is not something that i am aware has been tested as case law. It would definitely not be legal to sell it and possibly not distribute it.
Having said that, for home brew in your own home, it would be rather OTT to be pursued for this.
Here is a lengthy and occassionally heated discussion on the matter of https://www.brewuk.co.uk/forums/viewtopic.php?f=24&t=47682
Obviously, this is an Instructable intended to inform based on having tried it and liked it. I'm still standing, so for me the risks seem acceptable. What you choose to do is entirely up to you. I am not endorsing this, nor claiming it to be either safe nor legal in your country. Feel free to use it to decide for yourself.
Do so at your own risk, abiding by your local laws.