A blending idea

So I have about 20 gallons of beer souring right now and I would really like to do a blend of these. My LHBS sells an 18 gallon plastic barrel to ferment in, and I was thinking of blending about 15 gallons of my souring beer in it, then topping it off with some non-soured beer. The idea is to let it sit for some time, draw 5-10 gallons off of it for bottling, then replace those 5-10 gallons with more beer. I know that there are issues aging long-term in plastic, but I don't have the beer or the space for a full-on barrel, and I am wondering if there will be less oxygen exposure given the size of the plastic fermenter. Any ideas?

So basically you're doing a solera?

Plastic is generally very oxygen permeable. Except for the better bottles brand that is. I'd recommend finding a large demijohn, or converting a sanke keg into a fermenter.

Going that route its not really blending per se, in fact that method doesnt really allow you to blend batches to get something that tastes very good, which IMHO is the ONLY way to go about making a truly great sour

Whats wrong with leaving them in the carboys you currently have?

not really a solera either.... Since that would involve the blending through multiple ages to achieve a type of consistency... This is really just 'topping off'

ryane said:

Going that route its not really blending per se, in fact that method doesnt really allow you to blend batches to get something that tastes very good, which IMHO is the ONLY way to go about making a truly great sour

Whats wrong with leaving them in the carboys you currently have?

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You're right that it's not typical blending, but I was thinking of doing this because I could blend into one vessel and let the flavors co-mingle, and then I could add fresh non-sour beer to it. I want to add the non-sour beer to try and add some body, as that is what is most noticeably lacking in the sours I have. So if I add 3 gallons of 8-9% wort to it, I may be able to give it a little more body. Then the idea is that I can use it like a solera.

The biggest worry that I have is the oxygen permeability of this vessel.

Unless you pasteurize, new beer will be eaten just like every other bit of goodness...

el_exorcisto said:

unless you pasteurize, new beer will be eaten just like every other bit of goodness...

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+1

Andrewtherooster said:

You're right that it's not typical blending, but I was thinking of doing this because I could blend into one vessel and let the flavors co-mingle, and then I could add fresh non-sour beer to it. I want to add the non-sour beer to try and add some body, as that is what is most noticeably lacking in the sours I have. So if I add 3 gallons of 8-9% wort to it, I may be able to give it a little more body. Then the idea is that I can use it like a solera.

The biggest worry that I have is the oxygen permeability of this vessel.

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For our very relaxed purposes, we refer to this as a solera even though it is not technically operated like a solera operation it is close enough and produces something of a similar effect (you end up with a blend of beer that is multiple ages as you remove and replace beer).

The problem you have here is that the souring bacteria and brett will break down all the sugars. You'll never get more body unless you stop the fermentation process. You could change the flavor over time but anything that relies on residual sugar -- cara malts, maltodextrin, crystal malts -- won't have an effect on body. You could start with a very light beer and over time add dark beer additions to transition to a very dark sour. I'm not sure how successful it would be but it would be an interesting experiment.

I would also be concerned about oxygen permeability. If it's very thick plastic the permeability is probably much, much lower than an eight gallon bucket but I don't know how you could discover by how much.

ReverseApacheMaster said:

I would also be concerned about oxygen permeability. If it's very thick plastic the permeability is probably much, much lower than an eight gallon bucket but I don't know how you could discover by how much.

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If you measure the thickness of the plastic and find out the type, you can calculate the permeability. Raj Apte has published some numbers of some materials, and if you search enough, you can probably find numbers for different materials.

The numbers in Wild Brews (for various containers) are based on these numbers; finding the material thickness and the surface area of the container you can calculate the 'typical' permeability. Plastic (HDPE) is actually a lot less permeable than wood for the same thickness. I also seem to remember reading somewhere (maybe wild brews) that some big breweries keep their sours in large HDPE containers.

As for oxygen permeability, my thoughts are summed up fairly concisely in my signature. While the science may not be there to say that plastic is as good as glass, I have read reports of people doing year+ sour fermentations in HDPE buckets without any ill consequences.

If you are looking for more body in your sours try a different mashing method. What mashing method are you currently using?

JacobS said:

If you are looking for more body in your sours try a different mashing method. What mashing method are you currently using?

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I've use a single infusion with a batch sparge. Why would mashing affect body if all the bugs eat up excess sugars?

I guess I assumed that higher alcohol beer would add more body just due to the higher alcohol content, but I guess that isn't necessarily true?

The container is a cylinder with a diameter of 14", a depth of 26", and the thickness of the plastic is about 1/2". The surface area is about 1285 inches squared, if I calculated correctly. I haven't been able to find the graph that shows oxygen permeability given the plastics' surface area.

In addition to permeability through the walls of the plastic you also have to think about headspace. Is the design of the barrel going to result in a lot of headspace? That will also affect your beer.

It's really hard to say whether these fermenters are going to work out for you. Are they like converted trash cans or are they large HDPE demijohns (might be the wrong word to use)? The quality of construction, materials and design will definitely all be important components. Any thought on using a 15.5 gallon sanke keg instead?

It also matters how long you intend for this project to go on. If you're going to ferment a couple cycles and get 2-3 years out of it you're probably going to be ok. At worst your last batch may be strongly acetic. However if you plan to go much further your beer might get too acetic to enjoy and you'll end up with a big trash can full of vinegar.

It's actually a barrel used to store LME that my LHBS converts into a fermenter and sells for cheap. Filled up, the headspace won't be too much more than my standard carboy space. I think I'm going to try it. If it starts to become too acetic, I'll just empty it.

Andrewtherooster said:

The container is a cylinder with a diameter of 14", a depth of 26", and the thickness of the plastic is about 1/2". The surface area is about 1285 inches squared, if I calculated correctly. I haven't been able to find the graph that shows oxygen permeability given the plastics' surface area.

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What's the material (what is the recycle number on it)?

Half an inch is pretty thick. Comparing that to a barrel, I would estimate it is around 10 ccs/liter/year, which is pretty good; comparable to a large wine barrel.

O2 permeability of HDPE is about a third of that of oak.

I'll have to see what my LHBS does with their old LME barrels.

Or use a used 15.5 gal SS keg with a carboy cap.

If you are trying to build body from blending then you will want to blend your sour and big body beer and then pasteurize or inhibit the yeast w campden tablets. Ryane has some good info on his blog: http://ryanbrews.blogspot.com/2011/03/blending-and-fruiting-lambics-my.html

Calder said:

What's the material (what is the recycle number on it)?

Half an inch is pretty thick. Comparing that to a barrel, I would estimate it is around 10 ccs/liter/year, which is pretty good; comparable to a large wine barrel.

O2 permeability of HDPE is about a third of that of oak.

I'll have to see what my LHBS does with their old LME barrels.

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It's a number 2 HDPE.

Almighty said:

Or use a used 15.5 gal SS keg with a carboy cap.

If you are trying to build body from blending then you will want to blend your sour and big body beer and then pasteurize or inhibit the yeast w campden tablets. Ryane has some good info on his blog: http://ryanbrews.blogspot.com/2011/03/blending-and-fruiting-lambics-my.html

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Thanks for sharing! That was a great read.