open fermentation

dave althouse

dave althouse

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I watched a program (Brew Dogs) where they brewed a batch of beer on the roof of the Anchor brewery. It was an all grain and once they sparged the wort it was placed in an open barrel and the yeast was pitched. Left open to ferment on the roof. So, with all the precautions that one is suppose to take to keep the brew as sterile and free from outside "bugs" how does the open fermentation do that. I was just wondering

thanks

davea
 
They are taking some risk to ferment in open air, or they may want an odd bug or two for lambic barnyard notes. That is how it was done in olden times.
 
Open fermentation is a subject for experimentation and caution. You don't know what you're going to get when you open the fermentor to air. Yes, Belgian brewers once did so regularly but two things happened: Single-culture fermentation began and the cherry groves that harbored the beneficial wild yeast were cut down. Now most use cultured fermentation. So the caution: Who knows what funk you will get in your beer from a wild fermentation. It might be something great, it will likely be something worse than swamp water. You are far more likely to have a bad batch than a good one. That said, you might get something really great. If you do, be sure and keep a culture. Good luck with it, though, and by all means let us know how it turns out.

p.s. Any equipment that comes in contact with your open-fermented wort should not be used for regular beer making unless you can sterilize it completely.
 
believe it or not yeast cells are always floating around in the air, most likely they will join the colony and cause an off flavor, this technique will most likely cause bacteria to start to grow after the fermentation stops in 5 to 10 days.

People go crazy trying to seal the lids and keep it air tight but in reality not needed until after the fermentation stops because C02 is driving everything out
 
I brew in an open 10 gal. crock. I use a cover of saran wrap and a clean brew room. This works well for me with a vigorous fermentation and no funky flavors. The beer gets transferred to a closed secondary fermentor as soon as the activity dies down and the yeast starts to drop. The crock is easy to clean, allows air to the wort in the beginning of fermentation , allows easy SG measurements during the early fermentation, and allows top cropping of the yeast.

I have not had any issues with my open fermentor yet. Time will tell
 
I'd guess, if it's the kind of crock I'm familiar with, you have some of your own "house yeast" growing in the cracks and crevices in there! Likely whatever you pitch is going to overwhelm the small number of cells hiding out in your crock and as long as you don't pick up any anaerobic bacteria or wild yeast, you should be successful. My friends who make wine on the Mosel River only use wild yeast, the yeast growing naturally in the grape skins, and they seldom have any fermentation problems. Open fermentation works, it's just not predictable enough for some of us....
 
My fathers home brewing in a crock is what got me into brewing. He used a piece of plywood (with a hole in the middle for the hydrometer to stick out) for a lid. Every batch was different. some were awesome, some not so, but all were drinkable. Would batch it up (Premier prehopped Malt and cane sugar), drop in the packet of bread yeast, and wait for the hydrometer to say it was beer. He was always careful with cleaning bottles though, so all bottles from each batch stayed consistent. Batches varied a lot.
 
My crock is new with no cracks and no extraneous biology. It is cleaned and disinfected after each batch. All of my beers are fermented with a single culture starter of the recommended strength and develop into beers that are true to their standard.

It is possible to use old techniques with out being primitive. It is, however, necessary to be clean, sterile with the yeast, and to understand the biochemistry of beer making.

I will agree that it might be easer to get poor results from a crock then to get good ones. However, in my experience, there are brewing, and flavor advantages to a good open fermentation. A good crock is far superior to to an old scratch plastic bucket.

Tom
 
Crocks do have advantages as you point out. They would hold temp well also. I have talked to people who do the saran wrap and have to put a pin hole in it so it won"t bubble up. Dad didn't sanitize proper so he ended up with inconsistency. The mention of the crock brought back some good memories. I lost my dad last July, but still have the crock. Maybe I should try a few old school batches in it with a little more sanitizing? Hmmm
 
Considering that 'closed' fermentation is a relatively new thing (300 years or so) in the brewing history of the world (10K-12K years depending on which experts you believe), I'm kinda thinking that the layer of CO2 covering the beer in an open fermenter does a really good job of protecting the beer from airborne nasties. If not, then our ancient brewing brothers and sisters would have given up the art years ago. I just wish I had a dedicated brewing area (not the carport) in which to try an open fermentation. My single vessel brewing would be perfect for the process, but the BOSS would not like her car in the yard for 10-14 days. And the brew pot (25 gallon with 10-15 gallons of wort in it) is too heavy for transport.
Our modern airlocks and the knowledge of wild yeast and bacteria has given us much greater control of the brewing process and more consistent results. These (and the microwave oven) make me glad I'm a modern brewer.

http://byo.com/fermentation/item/1918-b ... -mr-wizard
 
I'm sure beer served from a moldy barrel with a leaky bung tasted goaty 300 years ago... However it was better than nothing.

This is equivalent to bars today that don't regularly clean their serving lines.

Open fermentation is done by some pro breweries like Anchor Steam. If I remember correctly on a documentary I was watching, a brewery that did this used air filtration systems and it was in a sealed room to keep insects out. Open fermentation doesn't mean open to contamination. It just means a shallower primary fermentor without a lid (this is how most red wines are fermented). As soon as fermentation is over, that beer is transferred and put under CO2 for cold conditioning.

This article talks about it more, and how it can lead to different ester profiles:
http://byo.com/stories/item/1211-open-f ... m-the-pros
 
Thanks Larry!

A very nice article on open fermentation with all of the major do's and don'ts.
 
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