Using a pumpkin as a fermentor?

Hey guys,

I'm a relative newbie (I've only brewed 5 or 6 times), but I have an idea that I just can't get out of my head. I want to incorporate my homebrewing into our Halloween decorations, and I'm thinking about buying a huge pumpkin and using it as a fermentor for a Pumpkin Ale.

First of all, I know that your typical jack-o-lantern pumpkins aren't the right kind for cooking with, so I plan to either bake some pie pumpkins or buy canned pumpkin for the flavoring. I just want to know if it's feasible to hollow out a pumpkin and ferment in it. I'm really excited about the decorative possibilities (creative airlock with spare tubing and food colored water bubbling away, etc.).

I'm also interested in whether a pumpkin might provide sufficient insulation to ferment outside (by protecting the beer from temperature swings while maintaining a relatively cool average temp.)

But what problems can you foresee with this?

This is the point where I place my youthful inexperience and naivete at the feet of your collective brewing experience and wait to have my idea shot full of holes.

Thanks in advance!

I have no idea if that would work or not but it sounds awesome! Please post pics if you decide to go ahead with it :rockin:

I swear I've seen pictures of someone do this once . . .

Only problem I can really imagine is finding a pumpkin large enough to hold 5 gallons... Maybe a mini batch?? Also, you'd probably want a real good yeast starter to make sure they'd be able to handle any of the nasties in the pumpkin. Is it possible to sanitize a pumpkin with starsan??

I would think it could be done with a very fresh pumpkin, but i would not leave it in there more than a week. i think it would rot quickly

" what is now in front of you may now be referred to as a ‘Tunkin’ " - That's awesome!

imperialipa said:

http://www.sloshspot.com/blog/02-25-2009/How-To-Brew-Pumpkin-Beer-in-a-Pumpkin-in-20-Easy-Steps-125

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I saw this when I googled around, but they didn't really address any difficulties they had in the process. I want to know things that might go wrong.

Sanitation was one that I had considered. I also wasn't sure if I could get the pumpkin air-tight after cleaning it out. And the insulation versus my typical BetterBottle carboy was a factor I wanted some input on. Is fermenting outside with 30+ degree temperature swings ALWAYS a beer-killer, or would the insulation negate that? Would the insulation cause the beer to heat up too much from fermentation?

These are the kinds of things I'm worried about, but the optimist in me is saying "Just go for it!"

I agree with your optimist, if you try a real simple ale and it goes bad, oh well. Otherwise you will have one sweet project around the house, a conversation starter for sure!

rancidcrabtree said:

Only problem I can really imagine is finding a pumpkin large enough to hold 5 gallons... Maybe a mini batch?? Also, you'd probably want a real good yeast starter to make sure they'd be able to handle any of the nasties in the pumpkin. Is it possible to sanitize a pumpkin with starsan??

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I was trying to decide if starsan would work, or if I could maybe use steam/boiling water. I don't see why starsan wouldn't work, but like I said, I'm certainly no expert on these things.

Also, I know lots of fruits and vegetables give off ethylene gases that help to ripen them. Do pumpkins do this? How might that affect the beer?

From http://extension.oregonstate.edu/fc...767_preserving_pumpkins_winter_squash2011.pdf

"Pumpkins and squash deteriorate rapidly if stored below 50F. Squash/pumpkins that have been exposed to freezing conditions before harvest do not keep well. Do not store pumpkin or squash near apples and pears. These fruits give off ethylene gas as they ripen which cause yellowing of the squash and shortens the storage life."

I'm guessing this means pumpkins don't give off ethylene gas, but also you'd want to make sure you found one that hasn't been in temps below 50 degrees.

Do it. That would be so Rad.

rancidcrabtree said:

From http://extension.oregonstate.edu/fc...767_preserving_pumpkins_winter_squash2011.pdf

"Pumpkins and squash deteriorate rapidly if stored below 50F. Squash/pumpkins that have been exposed to freezing conditions before harvest do not keep well. Do not store pumpkin or squash near apples and pears. These fruits give off ethylene gas as they ripen which cause yellowing of the squash and shortens the storage life."

I'm guessing this means pumpkins don't give off ethylene gas, but also you'd want to make sure you found one that hasn't been in temps below 50 degrees.

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huh, I would have thought that high temps would be worse. Anyway, I'm in Alabama, so that's not a huge problem (lows at night here rarely drop below 50 this time of year)

Monstar said:

Do it. That would be so Rad.

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If I actually do this, I'll wait until closer to Halloween, but I'll make sure to post pictures.

Now I really want to do this, only problem is that I don't think I can find a pumpkin here in Minnesota that hasn't seen a temp below 50 degrees at this time of year

Does it violate the intent to cram a fermenter into a pumpkin ? Maybe you could line the inside of the pumpkin with something ? That would fix the sanitation problem. Star San is an acid and may speed pumpkin decay

Random note: My first job was harvesting pumpkins at jones tree farm in ct hehe this sounds awesome good luck

This looks absolutely intriguing! To address sanitation, I would make sure to clean out the guts in a super clean environment, with clean tools. It's only being exposed to nasties after you pop the top off of it, just be careful when cleaning.

I would try one of the special pumpkins they actually use for pumpkin pies and stuff. They are sweeter than a regular one and might give a little more flavor. Im just not sure how big they come.

Jklinden said:

Does it violate the intent to cram a fermenter into a pumpkin ? Maybe you could line the inside of the pumpkin with something ? That would fix the sanitation problem. Star San is an acid and may speed pumpkin decay

Random note: My first job was harvesting pumpkins at jones tree farm in ct hehe this sounds awesome good luck

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Wouldnt the pumpkin inside be clean anyway since it hasnt had any exposure with the air (before its opened up)?

As far as I know, to reiterate the comment by FubgusBrew (very cool name)- the interior of the pumpkin is aseptic (free of germs) until the skin is breached- I would take a shot at it by star san-ing the outside, wearing elbow length (or longer) gloves, sanitizing them and a good stainless spoon (for scraping out the goo), as well as the knife used to cut it open. Do this procedure immediately before adding wort and a vigorous yeast starter- place the stem/lid back on and let ferment- positive pressure during primary should keep everything out- transfer to a glass carboy in about 3-4 days. BTW-I would like to see a picture of a big 'ol punkin with an airlock in it!

i am ready to try this!

Why not carve it out then fill with starsan, then toss your wort into it?

tremorfan said:

If I actually do this, I'll wait until closer to Halloween, but I'll make sure to post pictures.

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Yesssss.

I am doing this tmrw. TMRW U HER ME!!?

underground and under the influence

Hey go ahead and try it !!!!! Do a half batch this way if it doesnt come out like you hoped then the cost isnt that much of a loss.. I'd be interested in hearing how it comes out.

That's one of the craziest, but amazing things I've ever heard! I hope it works out for you! Please post some pictures of it if you decide to go ahead!!

such an awesome idea.you will be my hero even if the beer is undrinkable

Ill drink it. Idc.

underground and under the influence

rancidcrabtree said:

Is it possible to sanitize a pumpkin with starsan??

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That cracked me up

Good luck with the experiment. If it works, it would make a great pumkin ale recipe. Or even if it doesn't work, you could have one sitting around fermenting some sugar and water just for effect when your friends come over to drink it.

How about cheap vodka? Pour a bottle in and slush it around to make sure it is sanitized?

You could try emailing Cambridge Brewing Company if you have any questions, every year they take a massive 400-500lb pumpkin and age some of their great pumpkin ale in it until Halloween where they tap it and serve it at their brewpub festival. It's freaking amazing.

It's a new craze, vegetable/fruit fermentors!

Just think what you could do with a wheat in a watermelon?

Kind of a bizarre idea but as long as the fruit flies don't get the better part of the beer it seem quite possible!

My inner voice still is asking, why

I am not a wine drinker, but if you made wine this way you could serve directly from the pumpkin since wine is not carbonated. Just need a valve at the bottom. Now that I think about it I may do this the week before thanksgiving to serve the family wine with thanksgiving dinner. ooooooo I can elevate it in the middle of the table and put three or four valves around the sides so everyone can serve themselves. Then again.....maybe not.

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My friend and I were talking about doing the same thing yesterday. I believe -- and am encouraged by the "How to brew a pumpkin beer" article's pictures -- that the trick may be to have zero headspace.

Fill the liquid all the way up to your carved opening so that when you put the lid on, the lid touches beer. I think it will be much less likely to rot within the primary fermentation time if none of the innards are constantly exposed to air.

mrmekon said:

My friend and I were talking about doing the same thing yesterday. I believe -- and am encouraged by the "How to brew a pumpkin beer" article's pictures -- that the trick may be to have zero headspace.

Fill the liquid all the way up to your carved opening so that when you put the lid on, the lid touches beer. I think it will be much less likely to rot within the primary fermentation time if none of the innards are constantly exposed to air.

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I feel like that would be likely to blow the top off as well though. If there's liquid in there it should be at 100% humidity.

As has already been said, I also think that if you sanitize the pumpkin before you cut it and all the tools, and you fill it with wort and yeast asap, there shouldn't be any chance of infection.

But maybe you can somehow burn the pumpkin's interior a bit ;this should take care of nasties and add a different, maybe more interesting, flavor. I'm just saying.

sculpin said:

As has already been said, I also think that if you sanitize the pumpkin before you cut it and all the tools, and you fill it with wort and yeast asap, there shouldn't be any chance of infection.

But maybe you can somehow burn the pumpkin's interior a bit ;this should take care of nasties and add a different, maybe more interesting, flavor. I'm just saying.

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I had considered charring/caramelizing the flesh on the inside, but I don't really have any equipment for doing that. I assume I would need a blowtorch. But it's not a bad idea. I can't really think of another efficient way to cook the inside surface without weakening the structural integrity of the pumpkin.

Anyway, thanks for all of the support and interest, y'all. I talked to my brewing buddy today, and we're definitely going to do this. I plan on getting a smaller pumpkin to do a test run in the next week or so. I want to see how the internal temperature tracks over a 24-hr cycle, and I want to extrapolate that into a simplified heat transfer model to figure out what I would be looking at with a larger pumpkin with thicker walls (I'm a chemical engineering major, so I can't miss the opportunity for a real-world application of concepts). I'm also going to factor in the heat of reaction of fermentation to make sure the insulation won't hold in too much heat.

If anyone can think of other factors to check, let me know.

sculpin said:

As has already been said, I also think that if you sanitize the pumpkin before you cut it and all the tools, and you fill it with wort and yeast asap, there shouldn't be any chance of infection.

But maybe you can somehow burn the pumpkin's interior a bit ;this should take care of nasties and add a different, maybe more interesting, flavor. I'm just saying.

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I love this idea. You'd need a torch, something like a kitchen torch typically used for creme brulee would be perfect.

I think I may try that one of these days.