Open fermentation experiment

[pocketmon]

In a brewery fermentation CO2 production and sometimes CO2 pressure is inevitable. How are you going to determine what CO2 vs pressure effect? I know an English ale fermented under pressure as low as 5 psi is a very bland affair compared with its equivalent fermented open. I wonder what effect periodic N2 pressure has on yeast in an open fermentation?

THE BRÜ LAB podcast Episode 041 | Pressurized Fermentation w/ Dr. Andrew Macintosh might answer your question.

 

[bracconiere]

beer fermented in Denver should have a perceptible difference compared to beer fermented in San Diego

well coors says that all the time!

 

[McMullan]

@HighVoltageMan!, I'm still not convinced CO2 is the primary driver. There are several factors, including other stress factors, that reduce biomass production during fermentation to affect ester profiles. In my open (Yorkshire square) fermentations I control esters by repitching freshly cropped yeast relatively cool (17°C) at high pitching rate. Admittedly, recirculating the actively fermenting wort periodically knocks out CO2. if I pitch at a low rate to promote biomass production esters get a bit overwhelming in a poorly balanced beer.

@pocketmon, that was interesting, thanks. I'm going to read the publications to get a better idea about the experimental designs and their research. From what I could tell so far it sounds like pressure itself might be a confounding variable. Obviously, very difficult to tease apart the effects of CO2 vs pressure in a brewery fermentation. What we do know is under relatively unreactive N2 pressure the yeast gene expression profile changes.

 

[Oleson M.D.]

Pilsner Urquell still does open fermentation today.
Here are couple photos from their brewery, taken when we did a tour:

 

[McMullan]

Right, they haven't published much and, after listening to another podcast, I'm here: interesting theory to explain a correlation. Looking forward to some actual science to test and confirm what's being proposed.

Disclaimer: insufficient data to fact-check.

 

[McMullan]

I found this interesting, and, better still, it's publicly accessible. I'm thinking of messing around with a weak vacuum in yeast starters, although it's not clear if it increases biomass - I suspect it doesn't - it appears to keep more yeast cells in suspension, where we want them. The proposed benefits for fermentation are more for commercial brewers, I imagine. Pay attention to the methods and results for yeast propagation. They used dry Diamond Lager yeast. Their findings confirm what I've observed with dry yeast. Viability <50% and best propagated before pitching, preferably repitched, imo, to get them conditioned properly. I'm not sure why their wort gravity range was so narrow. Bit of a missed opportunity, like not measuring total biomass, before and after.

Here's the other podcast:

https://www.masterbrewerspodcast.com/230
If anyone has a copy of the MBAA article I could 'borrow' that would be very nice.

 

[FoodScienceBrewer]

Update: I put the airlock on the open fermentation vessel on Friday after observing consistent gravities over 2 days in the main bucket. I've been monitoring the gravity of the main (I tasted those samples and they are incredibly delicious. Banana, clove, and no off flavors. Exactly what I would expect from a Hefeweizen) which makes me excited to try the open fermented version. I have more bottles and caps arriving on Wednesday and I plan to bottle as soon as they arrive. If anyone is interested I will post tasting notes from the main batch vs the open fermented batch.

 

[Miraculix]

Update: I put the airlock on the open fermentation vessel on Friday after observing consistent gravities over 2 days in the main bucket. I've been monitoring the gravity of the main (I tasted those samples and they are incredibly delicious. Banana, clove, and no off flavors. Exactly what I would expect from a Hefeweizen) which makes me excited to try the open fermented version. I have more bottles and caps arriving on Wednesday and I plan to bottle as soon as they arrive. If anyone is interested I will post tasting notes from the main batch vs the open fermented batch.

That is too late, you will have already oxidised the batch. The trick is to airlock it before fermentation finishes.

 

[jambop]

Air lock shamare lock! Take a look here www.samuelsmithsbrewery.co.uk/ this is how proper beer has been made for centuries !

edit
I notice you are making a wheat beer... Again this style of beer has been made for centuries using open fermenting vats . As a very experienced brewer has told me there are very few air borne infections that can do much to a wort that has been supplied with adequate active yeast starter .

 

[CascadesBrewer]

Air lock shamare lock! Take a look here www.samuelsmithsbrewery.co.uk/ this is how proper beer has been made for centuries !

Note that the picture of open fermenters also shows a very active krausen. Once fermentation starts to slow, breweries will transfer the beer into a closed fermenter (well, centuries ago they may have transferred into a wooden vessel and the beer had some level of oxidation and sour character).

 

[FoodScienceBrewer]

That is too late, you will have already oxidised the batch. The trick is to airlock it before fermentation finishes.

There was still some airlock activity and a 1 inch Krausen layer after I put it on. I have a feeling it's gonna be fine. I'll follow up with tasting notes in a couple weeks and note if I detect any oxidation.

 

[cire]

There was still some airlock activity and a 1 inch Krausen layer after I put it on. I have a feeling it's gonna be fine. I'll follow up with tasting notes in a couple weeks and note if I detect any oxidation.

Not all yeasts can be used in open fermentation. Those suitable for this process produce a very thick coating and often need rousing to return yeast to the wort. Before fermentation is completed, they can be top cropped for the next brew, leaving a covering which lasts until the beer is racked.

 

[Nate R]

Back in the 1960's Dad would ferment his illegal beer in a 15 gallon crock with a towel over the top. I guess you would have called it open fermentation. The smell was fantastic!View attachment 780294

Do you still have this?!?!?
If so... well, you know.
And post pre, during, and post results and photos, etc..

 

[FoodScienceBrewer]

Just bottled it all yesterday. I wish I could've done it earlier but I was waiting on a shipment from Northern Brewer. I bought the dark star burner 2.0, a case of 22oz bottles, and caps. Lo and behold only the burner arrived with the shipment (was not notified of this). I said screw it and took the bus all the way to my local home-brew shop. Serves me right for not buying local I guess

 

[mamajack]

Hey @FoodScienceBrewer, notice this thread went dead before you posted comparative results on your beer. I'm curious to know what happened!

 

[cire]

Just to comment that I open ferment because my yeasts need any closed fermentation vessel to be at least 3 times the wort volume, while can be open fermented in a vessel of twice the volume. Even so, the yeast has to be returned to the wort to keep it within the vessel and also to maintain fermentation progress.

Such yeasts should not be allowed to drop to the bottom as primary fermentation finishes, but for they that do, the vessel needs then to be covered. It is usual to harvest such yeast by top cropping when fermentation reaches its maximum rate, leaving enough to cover the surface and when that flocculates provides a complete cover that will stay intact while the green beer is gently cooled and the active yeast clean up and drop out so the beer can be racked.

Open fermentation is not necessarily a suitable process for all yeasts.

 

[jerrylotto]

IMHO, the most important thing for an open fermentation is to eliminate air movement in the fermerntation area . If you put insulation strips around a closet door so it seals well, that should be sufficient. A plexiglass window would help to manage the curiosity factor and allow you to respond to unexpected things Maybe a small greenhouse?

 

[cire]

IMHO, the most important thing for an open fermentation is to eliminate air movement in the fermerntation area . If you put insulation strips around a closet door so it seals well, that should be sufficient. A plexiglass window would help to manage the curiosity factor and allow you to respond to unexpected things Maybe a small greenhouse?

That might work for the hobbyist, but in a commercial environment where it is not unusual, there can be dozen upon dozen of open fermenting vessels, each with 2 to 6 feet of wort covered by 2 or 6 feet of yeast. A brew might take 8 hours, but primary fermentation typically takes 7 days needing forced ventilation to disperse all the CO2 so produced to avoid killing any nearby workers.

 

[hottpeper13]

Check out Bell's Stairway to Heaven.

 

[jerrylotto]

That might work for the hobbyist, but in a commercial environment where it is not unusual, there can be dozen upon dozen of open fermenting vessels, each with 2 to 6 feet of wort covered by 2 or 6 feet of yeast. A brew might take 8 hours, but primary fermentation typically takes 7 days needing forced ventilation to disperse all the CO2 so produced to avoid killing any nearby workers.

This is Homebrewtalk, not Commercialbeertalk!

 

[bracconiere]

not Commercialbeertalk!

lol, depends on if you're a supporting member and have ads turned off!

 

[Nate R]

lol, depends on if you're a supporting member and have ads turned off!

Braccy- bravo! One of your best yet, Sir!

 

[cire]

This is Homebrewtalk, not Commercialbeertalk!

If the workers in Sam Smiths Brewery can observe their beer while it is fermenting,

have a pint and pose for a picture while standing by fermenting beer holding the side of an open fermentation vessel,

why shouldn't a homebrewer do similarly?

He could even provide a picture of an extant crust on day four when primary has finished and beer cooling gently while the yeast cleans up. This beer will be racked in 3 days time into a sealed vessel and naturally carbonate at ~50F in a week to ten days.

 

[beersk]

Check out Bell's Stairway to Heaven.

You mean New Glarus Stairway to Heaven

 

[FoodScienceBrewer]

Hey @FoodScienceBrewer, notice this thread went dead before you posted comparative results on your beer. I'm curious to know what happened!

My apologies. I did forget to post a followup. I stole a little from the main batch before I bottled it and noticed the banana/clove flavor characteristic of a Hefeweizen. This made me very excited. When I finally got to compare the two side-by side fully carbonated I did notice a significant difference in the phenolics/esters in the open fermentation batch (higher presence of the banana and clove flavor). The difference I noticed was mainly in the smell. I do remember noticing the open fermented batch did oxidize more quickly overtime and did not remain drinkable as long as the main batch. How much longer? I couldn't say. I've been committed to taking more detailed notes in my more recent brews.

 

[hottpeper13]

My bad, and I was there on a brew masters tour!

 

[mamajack]

My apologies. I did forget to post a followup. I stole a little from the main batch before I bottled it and noticed the banana/clove flavor characteristic of a Hefeweizen. This made me very excited. When I finally got to compare the two side-by side fully carbonated I did notice a significant difference in the phenolics/esters in the open fermentation batch (higher presence of the banana and clove flavor). The difference I noticed was mainly in the smell. I do remember noticing the open fermented batch did oxidize more quickly overtime and did not remain drinkable as long as the main batch. How much longer? I couldn't say. I've been committed to taking more detailed notes in my more recent brews.

Very interesting! Seems like this makes logical sense from what I've heard about open fermentations before - more ester & other flavor compound production but the threat of oxidation. Thanks much for the update!