Saturday, April 10, 2010

Double Concentrated Brewing

Double-Concentrated All Grain Brewing

When I began all-grain brewing I started out doing five gallon batches. Six hours later I had five gallons of wonderful homebrew. However, I found that five gallons just wasn’t enough to sustain a healthy supply of homebrew on tap at all times in my house, especially when I was only brewing once a month, if that. And, I found that trying to schedule a brewing session around running a business and raising a family was not as easy as I had first thought. I had to figure out how to brew more in one session with the equipment I already had on hand and I didn’t want to go back to doing extract brewing. What I had been using was a 7.5 gallon aluminum pot (turkey fryer) and an additional five gallon stainless steel hot liquor tank (HLT). After a few homebrews and some more quiet pondering a light bulb clicked in my head *ding*: Double-Concentrated all-grain batches is conceived.

What is a double-concentrated batch? Basically what you are doing is brewing up a concentrated batch of all-grain (think partial boil brewing from the extract days) and splitting that between two fermenters and topping up to five gallons of finished wort in each fermenter.

When brewing concentrated batches, generally speaking, all you need to do is double your grain bill for two batches. Now, because you are doubling your grain bill you must also have a mash tun that can handle the extra grain. The best part about double concentrated brewing is that you’re only doing a five gallon post boil volume. This means that if you batch sparge, you can still do it. All I had was a five gallon HLT and the 7.5 gallon pot and it worked great. I have a 12 gallon rectangular cooler which holds a maximum amount of 28 lbs of grain. Depending on your efficiency, this can yield you a final gravity (after dilution) of 1.060. Not bad!

Figuring IBUs

The tricky part with brewing is figuring out how much hops you need to attain your IBU (International Bittering Unit) range within the style your making. An easy way to get around this is using brewing software like Beersmith, Beer Tools or Promash. As your sugar concentrates in the wort, your hop utilization decreases. In other words, the more sugar you have in your wort, the harder it is to chemically break down (isomerization) the essential oils in the hops that impart bitterness and flavoring to your beer. Doubling the amount of hops doesn’t necessarily mean you’re going to get the same IBU’s that you would get from a full wort boil. If you don’t have a software program but have internet access, there are plenty of free sites that have IBU calculators: rooftopbrew.net and realbeer.com are just two of many.

With a concentrated batch, the IBU’s will be limited. Given that our palates only perceive 100 IBU’s, we need to factor this into our recipe and since we are boiling one batch of beer and splitting it in half, logic tells we will only have a maximum of 50 IBU’s into each batch of beer. Now because our senses only perceive a maximum of 100 IBU’s, that does not mean that you can’t add more to your wort. The sky is the limit when it comes to homebrewing.

Here is how it breaks down. Collect 6.5 gallons of wort, boil that down to 5 gallons over 60 minutes and split that between two fermenters. Dilute this by half by adding 2.5 gallons of water; leaving you with 50 IBUs in your final product.

Keeping in mind the bitterness limitations inherent with double-concentration brewing, it is not always the best choice. If you want to brew an Imperial IPA, this technique is not the way to go. However, one can brew plenty of other styles that fall under the 50 IBU range: Pale ales, Lagers, Milds, Browns, Stouts, Porters . . . really, the list is long.

Here is a simple recipe that has become a standard must-have on tap at all times in my house. You’ll see the high gravity readings; bitterness this is your final Starting Gravity BEFORE dilution. In order to understand your final Original Gravity, just divide that number in half and you’ll have it. Concentrated S.G.: 1.125/2 = 1.056. That’s the original gravity of your beer.

Batch size: 5 gallons
Boil size: 6.5
Efficiency: 75%

21.00 lb Pale Malt (2 Row) UK (3.0 SRM) Grain 89.82 %
1.00 lb Cara-Pils/Dextrine (2.0 SRM) Grain 4.28 %
1.00 lb Caramel Malt - 40L (Briess) (40.0 SRM) Grain 4.28 %
0.38 lb Chocolate Malt (450.0 SRM) Grain 1.63 %
2.00 oz Amarillo Gold [8.90 %] (5 min) flavoring 8 IBU
2.00 oz Amarillo Gold [8.90 %] (60 min) (First Wort Hop) Hops 40.3 IBU
2.00 oz Cascade [6.60 %] (60 min) Hops 27.2 IBU
2.00 oz Amarillo Gold [8.90 %] (10 min) Hops 13.3 IBU
2 Pkgs Safale (DCL Yeast #US-05) Yeast-Ale

Est Original Gravity: 1.125 After you dilute: 1.056
Est Final Gravity: 1.031 After you dilute: 1.015
Bitterness: 80.8 After you dilute: 40
Color: 23.4 After you dilute: 11.7

Mash in 7.3 gallons of water at 166 degrees
Batch sparge with 2 ¼ gallons of water.

So, the next time you do an all-grain batch, why not try a double-concentrated batch? It takes the same amount of time as a five gallon batch, and your yield is twice as much. Why settle for one, when you can get two for one in a single batch!