IPA: Plastic fermenter vs corney keg

[Burquebrewer]

I brewed a batch of American IPA using Calypso and El Dorado hops. Total IBU's are at 69 on this one. I brewed up 10.5 gallons then split it into two different fermenters, 4.5 gallons went into a corney for fermentation and 6 gallons into a plastic 7 gallon big mouth bubbler.

Here is the thing that I find interesting...

When I opened the primary for each to test gravity, etc, the keg has a strong hoppy smell but the plastic smells flat, no beautiful, hoppy aroma? They both taste good, no off flavors or anything other than those from still being green and needing a little more time on the yeast to clean up.

A few more facts:

The keg was filled first and pitched at 66.
The plastic was filled second and the chiller was struggling a little. I pitched at 71 and cooled quickly to 68 after in an ice bath.

Both were well aerated with a aeration stone and pump. I split three packs of US-05 split between the two fermenters. Temp control used for both and fermentation took place at 68 F. No dry hops placed in either yet. Both are at 9 days in primary.

Could the plastic have allowed the hop aromas to escape? Could the shape of each fermenter have anything to do with it?

Anyone else have any similar experiences? Thanks in advance for the input.

 

[kh54s10]

I can't imagine the material of the vessel had anything to do with the difference. At least not in that time-frame. Plastic is somewhat gas permeable, but it would take a lot longer than that.

Was the airlock system the same for both?

 

[TheHopfather]

I can't imagine the material of the vessel had anything to do with the difference.

You would think that it wouldn't matter. The Brulosophy guys have done 4 xBmts on fermentation vessel type/size and I think 3 of the 4 reached statistical significance. Apparently the type of fermentor used does impact the final taste of the beer. Here is a link to the glass carboy vs corny keg xBmt, closest one to what you've done;

http://brulosophy.com/2017/02/13/fe...orny-keg-vs-glass-carboy-exbeeriment-results/

 

[kh54s10]

You would think that it wouldn't matter. The Brulosophy guys have done 4 xBmts on fermentation vessel type/size and I think 3 of the 4 reached statistical significance. Apparently the type of fermentor used does impact the final taste of the beer. Here is a link to the glass carboy vs corny keg xBmt, closest one to what you've done;

http://brulosophy.com/2017/02/13/fe...orny-keg-vs-glass-carboy-exbeeriment-results/

I just read that and I think you need to look at again.
" all factors I was convinced would have a noticeable impact but didn’t, while such an oft dismissed issue as the type of container beer is fermented in actually appears to have a qualitative impact. Crazy."

It appears the material makes no difference.

 

[Dcpcooks]

Fermentor shape/size/ surface area all play a role in the final product. That's one of the big challenges a brewery faces when they expand.

I'm surprised your seeing that big of a difference.

Did you ferment under pressure in the keg?

 

[TheHopfather]

I just read that and I think you need to look at again.
" all factors I was convinced would have a noticeable impact but didn’t, while such an oft dismissed issue as the type of container beer is fermented in actually appears to have a qualitative impact. Crazy."

It appears the material makes no difference.

I'm not sure how you are getting that out of the linked article... From the "Results" section of the xBmt;

"While the minimum number of correct responses required to reach statistical significance is 15 (p<0.05), a total of 16 tasters (p=0.013) accurately identified the unique sample. These results suggest participants in this xBmt were able to reliably distinguish a beer fermented in a corny keg from the same beer fermented in a glass carboy."

Plus there are 3 more xBmts linked off of that first one, all about fermentor type. 2 of those 3 also reach statistical significance. I think you may have misread something.

 

[kh54s10]

I'm not sure how you are getting that out of the linked article... From the "Results" section of the xBmt;

"While the minimum number of correct responses required to reach statistical significance is 15 (p<0.05), a total of 16 tasters (p=0.013) accurately identified the unique sample. These results suggest participants in this xBmt were able to reliably distinguish a beer fermented in a corny keg from the same beer fermented in a glass carboy."

Plus there are 3 more xBmts linked off of that first one, all about fermentor type. 2 of those 3 also reach statistical significance. I think you may have misread something.

Look further down. The quote is from the same page. In the discussion.

Besides that there is this: "The carboy fermented beer was preferred by 6 tasters, 3 reported liking the keg fermented beer more, 3 had no preference despite noticing a difference, and 4 felt there was no difference."

So even it statistically they could pick the right one really there is little difference. Because some liked one over the other, others felt there was a difference but had no preference, and others thought there was none.

The author also said in his testing he only picked the right one the amount of times consistent with the number of samples.

 

[Burquebrewer]

I can't imagine the material of the vessel had anything to do with the difference. At least not in that time-frame. Plastic is somewhat gas permeable, but it would take a lot longer than that.

Was the airlock system the same for both?

The airlock system was the same for both, a standard one-piece airlock filled with tap water; however, I noticed quickly that the lid on the keg was not a tight seal and there was little activity in the airlock on the keg indicating that the pressure was escaping through the O ring in the keg lid... however, the gravity in both is the same at this point, so fermentation was the same in both. I can also see the krausen ring just above the liquid in the keg.

 

[Burquebrewer]

Fermentor shape/size/ surface area all play a role in the final product. That's one of the big challenges a brewery faces when they expand.

I'm surprised your seeing that big of a difference.

Did you ferment under pressure in the keg?

No I did not. Fermentation was the same for both, other than the vessels being different, all procedures the same.

 

[Burquebrewer]

Is it possible that the amount of trub in the plastic could have had an effect? Since the keg was filled first, I suspect everything that went into it was very clear; however, the carboy was filled second and the wort was not as clear toward the end of filling.

I'm sure it wasn't a lot of trub, but then again, there was essentially none in the keg...

 

[Staticsouls]

I notice that my plastic vessels used to take on the smell of the beer brewed in it,no matter how much I soaked or cleaned em. I have since gone all ss.

 

[d3track]

the part that jumps out to me is that you had ~1/3 more wort in the plastic fermentor as the keg, with the same amount of yeast in both. I'd think that could have a fairly significant impact in the flavor.

 

[Burquebrewer]

the part that jumps out to me is that you had ~1/3 more wort in the plastic fermentor as the keg, with the same amount of yeast in both. I'd think that could have a fairly significant impact in the flavor.

Maybe, I would think though, that if anything, I just over-pitched the 4.5 gallon batch. From what i've read, overpitching on a homebrew level has very little impact....

I wouldn't suspect that 1.5 packs of us-05 in 6.5 gallons would be under-pitching?

 

[d3track]

Maybe, I would think though, that if anything, I just over-pitched the 4.5 gallon batch. From what i've read, overpitching on a homebrew level has very little impact....

I wouldn't suspect that 1.5 packs of us-05 in 6.5 gallons would be under-pitching?

While it may not be under-pitching, but I suppose it could cause a difference in flavor.
Your trub theory could be interesting too, especially if there was a lot of hop material.

 

[Upthewazzu]

This is interesting to me since I just started using a 6.5 gal plastic big mouth bubbler as my primary fermentor. Previously I had used plastic buckets (for 5gal batches) or glass carboys (for 3 gal batches).

My first batch in the BMB was an IPA that was a lot more muted than some of my previous IPA's. I haven't been able to determine if it was an equipment issue or recipe issue.

 

[Burquebrewer]

This is interesting to me since I just started using a 6.5 gal plastic big mouth bubbler as my primary fermentor. Previously I had used plastic buckets (for 5gal batches) or glass carboys (for 3 gal batches).

My first batch in the BMB was an IPA that was a lot more muted than some of my previous IPA's. I haven't been able to determine if it was an equipment issue or recipe issue.

The wall of these fermenters are so much thinner than any other fermenter I've used, so I am curious if they do allow more to escape. I guess it is time to whip up another IPA and separate it into multiple fermenters again as an experiment to test this. Perhaps I'll brew 14 gallons and split into three vessels... a Big Mouth Bubbler, a SS keg, and a glass carboy. See if the difference in still there in terms of the hop aroma.

This time, I will fill them each in equal one gallon increments to try to keep all other factors as close as possible.

As for this batch, I just kegged it today, so I'll know in a few weeks if there is a difference in taste as well as smell...

I'll update the post here with the findings...

 

[Burquebrewer]

While it may not be under-pitching, but I suppose it could cause a difference in flavor.
Your trub theory could be interesting too, especially if there was a lot of hop material.

There was a bit of hop material in the trub, but most of it wound up in the plastic, which had very little hop aroma?

When I kegged today, the batch from the keg definitely still smelled a lot hoppier...

 

[Burquebrewer]

Update on this, after 9 days in the keg and force carbed at 25 psi for three days then 12 psi for three days, here is the situation.... The beer fermented in the plastic has a lot less hop flavor and aroma. It is significant.

Here are my conclusions:

There was less trub in the keg, and less hop material as a result, but the keg has more hop flavor/ aroma...

There was less volume in the keg - 4.5 gallons fermented in a SS corney and 6 gallons in 7 gallon plastic BMB...

There was less headspace in the keg during fermentation, but again, it was not as airtight as I never saw much airlock activity on the keg. I'm guessing pressure was escaping through the O ring on the lid of the keg....

There was more yeast per volume in the keg... I split three packs of US-05 between both batches

Obviously, the shape/ size/ and material of the two fermenters were different.

 

[Burquebrewer]

Recipe and schedule as follows:

10.5 gallon batch

21.5 lbs of us 2-row
1 lb 60 Crystal
1.5 oz Maltodextrine
.5 oz Calypso at 60 min (14 AA)
1 oz Calypso at 40 min (14 AA)
1 oz El Dorado at 20 min (12.2 AA)
.5 oz El Dorado at 15 min (12.2 AA)
1 oz Calypso at 5 min (14 AA)
.75 oz Cascade dry hopped in keg for 7 days

I mashed in at 152, boiled for 90 minutes, came out with 10.5 gallons.
The keg was filled first with 4.5 gallons and pitched at 66.
The plastic was filled second with 6 gallons and the chiller was struggling a little. I pitched at 71 and cooled quickly to 68 after in an ice bath.

Both were well aerated with a aeration stone and pump. I split three packs of US-05 split between the two fermenters. Temp control used for both and fermentation took place at 68 F.

I put 4.5 gallons of the beer from the plastic fermenter into a keg after 15 days. Drawn through the spout.

I also transferred the 4.5 (4.25 gallons after loss to yeast sediment) into a second keg after 15 days in the first keg acting a primary fermenter.

Waited three days, then put in the keezer at 40. Dry hopped with .75 oz of Cascade spilt equally by weight between the two ( hops in SS tea balls).

What the heck?!? Why so much difference the hop flavor and aroma between the two batches?