Glass or plastic?

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Calder

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I've got 6 gallons of a base beer fermenting and a gallon starter (wild) that I am planning on combining this coming weekend.

I do not want to contaminate my normal fermenters so I'm going to be using some smaller ones I have available. I have lots of Imperial gallon glass fermenters (1.2 US gallons) and several 2.5 gallon HDPE containers (thick, food grade) that I occasionally use for small batches and ciders.

Which would be the better ones to use. Up to now I've used the glass carboys with standard rubber bungs and airlocks, and have been pleased with the results, but the beers have not gotten as sour as I would have likes. For a few gallons, I've moved the beer into HDPE containers to put the beer on fruit for 6 months, and those have gotten noticeably more sour; pretty good actually, but it might have been some acids from the fruit itself that I was tasting.

Would like to hear other's thoughts; Use the almost airtight glass, or the 'breathable' plastic?

I think I'm going to try and experiment and put 2.5 gallons in plastic, and 4.5 gallons in glass, and compare them at 6 months (thought I would make a decision at that time as to whether to move it to glass or leave it in the HDPE container).
 
From what I've read, no experience, the plastic has oxygen permeability which will allow more acids to be produced. I heard jamil say on his Flanders red show that he like the plastic better. Hope that helps
 
I think splitting them would be a great idea. And helpful for others to learn.

To be honest I don't know what will work better. I have always used glass or stainless (corny kegs) because I am afraid of too much oxygen and producing acetic acid. I personally don't mind some acetic acid in my sours. But what I'm afraid of because I only taste every 3 months is that I give the beer plenty of time to turn into vinegar.

Please update with your results and tastings.
 
With greater oxygen permeability you are going to get more acetic acid. That's good for a flanders red but not for lambic or oud bruin, so it depends on what acid flavors you want.
 
@ReverseApacheMaster
I have heard all the debates about the oxygen permeability, but I have yet to read someone actually doing a side by side test on sour beer. If you have some experience or a reference, that would be nice to read.

I know the oxygen permeability is much higher in HDPE, but do we know that it is too much?
 
I think splitting them would be a great idea. And helpful for others to learn.

To be honest I don't know what will work better. I have always used glass or stainless (corny kegs) because I am afraid of too much oxygen and producing acetic acid. I personally don't mind some acetic acid in my sours. But what I'm afraid of because I only taste every 3 months is that I give the beer plenty of time to turn into vinegar.

Please update with your results and tastings.

Will post updates as I learn anything. I too have heard that HDPE allows a lot more O2 than the traditional barrels, but have never seen anything saying that it is too much.

APM, strange you should say that about Lambic vs Flanders and the acid type. I always thought it was the other way around, with the Lambic having the more harsh acidity. I also think Flanders barrels are kept topped up, so should be good and tight, whereas Lambic aren't and therefore can dry out at the top allowing more air to enter. Maybe I've got them switched around, but that's what I thought. Probably go and look that up later.

Edit: Checked in Wild Brews, and based on their limited evaluation of beers, Flander's does have higher acetic acid over Lambic. Apologies to APM.
 
Update on glass vs HDPE (#2).

Background: Brewed 6 gallons Lambic base 9/24/11 (Gravity 1.056). Racked 10/6/11 (Gravity 1.018) to four 1-gallon glass fermenters and to one 3-gallon HDPE fermenter and added bug mix starter (6 pints) evenly to all. Topped up with fresh wort.

Bug mix is a mix of Brett, and dregs from several sour beers; mostly JP. Starter was made 2 weeks before adding to base. 6 pieces of toasted oak dowel was also in bug starter, and then added to each gallon.

12/25/11. 11 weeks after racking. Checked HDPE and one of the glass fermenters. Both had a thin pellicle. Both were 1.013 gravity. Both tasted identical. Lots of acidity in both samples, clean with no evidence of vinegar. Both seemed thin on body, little to no Brett flavors had developed.

Will top-up both fermenters with 6 ozs of freshly fermented beer (fermented sacc base for a Flanders Red), and check again in about 3 months. Will be conducting the same experiment with latest Flanders.

Conclusion: For this beer, at 3 months, glass vs. HDPE seems to make no difference in souring beer.
 
Thanks for the update.
So the HDPE bucket is using the same style airlock as the glass jugs?
And all the containers had the same small amount of head space?
 
Thanks for the update.
So the HDPE bucket is using the same style airlock as the glass jugs?
And all the containers had the same small amount of head space?

All use an 'S' type airlock with vodka. Glass jugs use a traditional rubber stopper. HDPE has a grommet in a drilled hole in the plastic cap which holds the airlock (similar fashion to a bucket).

Due to the shape of the HDPE container, it has more headspace than the gallon glass carboys.

All-in-all everything points to things being a lot worse/different in the HDPE container.

Thus far all the containers have had positive pressure, so that might enable CO2 to be retained in the airspace, minimizing any O2 entering.

In the end I topped up both containers with 6 ozs of starter wort (unfermented). To replace the sample taken out, and to create some small amount of fermentation to re-fill the headspace with CO2.
 
Update on glass vs HDPE (#2).

Background: Brewed 6 gallons Lambic base 9/24/11 (Gravity 1.056). Racked 10/6/11 (Gravity 1.018) to four 1-gallon glass fermenters and to one 3-gallon HDPE fermenter and added bug mix starter (6 pints) evenly to all. Topped up with fresh wort.

Bug mix is a mix of Brett, and dregs from several sour beers; mostly JP. Starter was made 2 weeks before adding to base. 6 pieces of toasted oak dowel was also in bug starter, and then added to each gallon.

12/25/11. 11 weeks after racking. Checked HDPE and one of the glass fermenters. Both had a thin pellicle. Both were 1.013 gravity. Both tasted identical. Lots of acidity in both samples, clean with no evidence of vinegar. Both seemed thin on body, little to no Brett flavors had developed.

Conclusion: For this beer, at 3 months, glass vs. HDPE seems to make no difference in souring beer.

4/21/12. 7 months after pitching bugs. Checked HDPE and a glass fermenter (Same HDPE container, but different glass fermenter than previous check). Glass was 1.012, HDPE was 1.010. Both tasted identical; I could not detect any difference in sweetness, and sourness was the same in both. Tasted samples back and forth several times.

Acidity was clean with no evidence of vinegar. Both tasted great, and would make a great beer being served without carbonation now. Still had little to no Brett flavors.

Conclusion: For this beer, at 7 months, glass vs. HDPE seems to make no difference in souring the beer.

This is the last update for this beer. I have moved the beer from the HDPE container onto some fruit so cannot make any future comparisons.
 
Thanks for running this test. I was debating with myself between the two. I will probably go with the glass carboy, since i like to peek on the beer and pellicle without removing the lid of a plastic bucket etc.
 
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