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View Full Version : TOTM, 6/07: Fermentation



jeff
06-07-2007, 04:08
This month we'll continue Bourbon Making 101 with a discussion of fermentation. Discussions should include a description of fermentation, different yeast strains available, propagation of "ancient" strains vs. using commercially available yeasts, open vs. closed fermenting vats and who uses what, attenuation, back-set, or any other topic related to yeasts, on their quest to turn sugar into liquid gold!

:Clever:Sound off:Clever:

BourbonJoe
06-07-2007, 06:18
I noted from many distillery tours that most distillers start with a certain gallonage (%) of backset to start a new batch. Four Roses takes a more scientific approach and bases the amount of backset on pH. Interesting.
Joe :usflag:

barturtle
06-07-2007, 06:51
Okay open v. closed:

Here's what I can recall from tours:

Open:
Makers (though not having gotten in to see the unoffical stainless fermenters, they could be different)
Buffalo Trace
Wild Turkey

Closed:
Jim Beam

I can't seem to recall What Four Roses and Woodford use...must be time to revisit them. Any one know them or Heaven Hill or Brown Forman or Barton?

I must say I like the idea of some "wild" yeast being able to get in there to add some flavor depth, but then again in some ways consistancy is key.

Gillman
06-07-2007, 07:01
Open fermenters, especially where fermentation is done at ambient temperatures as in Kentucky I understand, often would produce an estery beer, which lends a fruity taste that is noticeable in many new distillates and can show in the final aged product. Open fermenters are used classically with top fermentation yeasts (but are used with bottom yeasts too, e.g., as originally at Pilsen for its Urquel) and I think this kind of yeast still is the norm in the bourbon industry (whether jug or cultured).

E.g., Woodford and its related whiskeys seem to have a cherry-like taste which may be a product of this yeast character. I find something similar in, say, Weller 107. Some whiskeys seem to stress a peach or apricot character.

Closed fermenters would lessen the chance of estery effects although it depends too on the temperature of the fermentation. I understand that even top yeasts tend to behave like bottom ones in closed fermentation vessels, especially the tall inverted cone-type units. This would result in a more neutral character from a yeast standpoint.

Another point about liquor fermentation: you want a high degree of attenuation, you don't want residual sugars to lend taste because that represents (in distilling as opposed to brewing beverage beer) wasted alcohol.

Gary

Edward_call_me_Ed
06-07-2007, 07:42
Can I ask a dumb question?

How can they use open top fermenters without ending up with vinegar at least some of the time?

Ed

Gillman
06-07-2007, 07:52
Well, the yeasts are stable enough, and the fermentation controlled enough (including not over-prolonging it), not to have these accidents occur (although probably they do occasionally, as most brewers can state I think). The interaction though of some wild yeast with the yeast working in the brew may give some house character to some beers, you see this with a number of Belgian ales which have a sourish or acid taste. In balance though, that can be a plus.

Gary

bobbyc
06-07-2007, 08:08
Barton = Closed
Woodford = Open

Don't know the rest

Gillman
06-07-2007, 08:36
It's interesting because of the distilleries identified as using closed fermenters, their products to my taste have the least estery taste in the industry. Barton's whiskeys seem very clean in general, and so are Beam's, even Knob Creek (not to mention Booker's and Baker's) doesn't really have an estery component. True, Beam Black sometimes achieves an estery quality but I find this is the exception.

The plants using open fermenters however all seem to tend in the opposite direction: OF and WR are notably fruity, so is Rare Breed and many WT bottlings (not all, but that probably results intentionally from mingling to achieve certain profiles), yet Maker's seems (I admit) not to be (and I am assuming the current stock was all made before the sale). Probably the specific yeast used despite the open fermentation imparts little estery character or maybe they ferment at a lower temperature than the others who use open fermenters.

I think the type of yeast (even amongst the top yeast group) and especially fermentation temperature has the greatest say, yet still with little other data it is interesting that most of the open fermenter distillers produce relatively fruity whiskeys. I wonder what Trace does, I would think they must use open fermenters but possibly not, or maybe they use both types?

Gary

boone
06-07-2007, 08:37
We call them "mash tubs". Heaven Hill's is closed.

I took these pictures at Maker's Mark. Open mash tubs and view of how they monitor and control the work area in the distillery.

The PLC is the heartbeat in today's distilling industry. The "old distillery-DSP #31" had very little "new technology". Craig told me that they spent a lot of time "redoing" Bernheim. The entire process was controlled by PLC. They have modified Bernheim it so that certain elements are "turn key" or "human hand" operation so to speak.

Gillman
06-07-2007, 08:41
Bettye Jo, is the fermentation stage done in a different vessel or do they mash in and add yeast to the one tub?

Gary

boone
06-07-2007, 08:55
Bettye Jo, is the fermentation stage done in a different vessel or do they mash in and add yeast to the one tub?

Gary

Actually, the process goes like this...From the mash cooker to the fermenter for 4-7 days then to the "beer well"...and then fed to the still. All different holding tanks.

Gillman
06-07-2007, 09:01
There is therefore another variable, open vs. closed mash tubs, and I wonder what effect either has on mash characteristics. One would think, using an analogy from stove-top cooking, that more "flavor" is preserved in a closed mash tub.

Gary

boone
06-07-2007, 09:15
Here's a good "Visual" from Craig, describing the entire process from start to finish...

http://www.heaven-hill.com/virtualTour/virtualTour.html


There is therefore another variable, open vs. closed mash tubs, and I wonder what effect either has on mash characteristics. One would think, using an analogy from stove-top cooking, that more "flavor" is preserved in a closed mash tub.

Gary

Gillman
06-07-2007, 09:54
Great video, I've been to the site many times but never saw that!

The fermenters too appear to be closed, or once the hatch is shut.

Gary

bobbyc
06-07-2007, 10:22
Not to go afar but I'd like to throw this into the mix. Once Jimmy Russell was at Turnpike Liquors signing bottles. I had him sign my split label 12 year and bought the 101 RR there and he signed that too. I asked him about fermentation, brought on by a recent visit to Makers Mark where they told us on tour that they sent the fermented mash to the Beer Still before the fermentation was 100% done, another caveat that "Made" Maker's better and more expensive. He said they had no practice as such at Wild Turkey and for them the key was to control the fermentation from start to finish with their yeast and not to have a secondary fermentation begin in the tubs.

boone
06-07-2007, 10:44
Thanks Bobby :grin: :grin: I just love those "extras" folks add :grin: :grin: :grin:

We no longer use the "old style" cypress mash tubs aka fermenting tanks. The distillery burned and they were history. Not completely destroyed though. The "cypress" lumber was recycled. It lives again except in another form :grin: :grin: :grin: When you visit the Bourbon Heritage Center, go inside the "barrel tasting room"....The counter top on the bar is made from the old cypress mash tubs from the distillery that bruned...

As of late, the lumber has started to dry, cracks in the "see your face shine" counter top are everywhere. I guess being used to ferment all those years it will take a long, long time for the lumber to completely dry. This has been accepted and gives "good character" to the bar :grin: :grin: :grin: When the drying is complete and the cracks subside, another seal will be added to the counter top...

Just beautiful :grin: :grin: :grin:


Not to go afar but I'd like to throw this into the mix. Once Jimmy Russell was at Turnpike Liquors signing bottles. I had him sign my split label 12 year and bought the 101 RR there and he signed that too. I asked him about fermentation, brought on by a recent visit to Makers Mark where they told us on tour that they sent the fermented mash to the Beer Still before the fermentation was 100% done, another caveat that "Made" Maker's better and more expensive. He said they had no practice as such at Wild Turkey and for them the key was to control the fermentation from start to finish with their yeast and not to have a secondary fermentation begin in the tubs.

BourbonJoe
06-07-2007, 10:48
Okay open v. closed:

Here's what I can recall from tours:

Open:
Makers (though not having gotten in to see the unoffical stainless fermenters, they could be different)
Buffalo Trace
Wild Turkey

Closed:
Jim Beam

I can't seem to recall What Four Roses and Woodford use...must be time to revisit them. Any one know them or Heaven Hill or Brown Forman or Barton?



You can add Four Roses to the open list.
Joe :usflag:

Gillman
06-07-2007, 13:50
Four Roses makes notably fruity whiskeys.

Gary

bobbyc
06-07-2007, 17:57
Actually Barton has a very interesting set up on their fermentation tanks as they are free standing and most of the tank is outside in the weather and a small portion of each is inside a building with a walkway and roof arrangement.
I just looked, I don't have a picture of that part of their building.

This is not to infer any effect on the mash just a design characteristic of the building.

cowdery
06-07-2007, 19:36
I can only speak to what I've been told and just about every distiller at some time or another has told me there is no difference between open and closed fermenters. The people with closed fermenters chose them so they would be ready to capture the carbon-dioxide by-product if it ever becomes necessary or desirable to do so. Obviously, all of the closed fermenters are stainless steel. I assume closed gives a little more control over temperature, but not much since they aren't insulated. A lot of people understand the science of fermentation better than I do, but it appears to me that people with open fermenters don't have any problem preventing the environment from becoming contaminated.

Gillman
06-07-2007, 20:08
From my beer knowledge, I understand that in a sealed fermenter, the yeast tends to behave differently than in an open fermenter. Many closed systems are designed to allow the yeast to collect and form at the bottom, for easier removal. When the yeast does this, it tends to act as a bottom yeast and tends to form rounder, less estery beers. When the yeast works at the top (and I understand most bourbon distillers use top-ferment yeasts), it has to be skimmed off or the liquid drained from under it. Exposure to open air seems to result in more "characterful" styles and non-precipitation tends to produce more estery beers, at least at ambient temperatures. Whether all this applies to distilling fermentations, I do not know, but I find it interesting that of all the systems mentioned, the closed ones except for Maker's tends to produce notably non-fruity distillates (or at least, that is my experience). As for Maker's, the factors mentioned by Bobby may play a role too, I think what was meant was, by not doing a full attenuation, they retain more flavor in the mash but the yield of course is less. Jimmy's concern is very valid because multiple uncontrolled ferments can damage flavor.

Gary

Edward_call_me_Ed
06-07-2007, 20:13
Betty Jo said that the fermentation takes 4 to 7 days. Is that the norm? If that is so it must be a very vigorous ferment which might go a long ways toward explaining why it is rarely contaminated.

Anyone know how much yeast is added to the beer?

Ed

barturtle
06-07-2007, 20:17
Okay so it now stands at:

Open:
Four Roses
Buffalo Trace
Wild Turkey
Makers Mark
Woodford Reserve


Closed:
Jim Beam
Heaven Hill
Barton

That just leaves Brown Foreman to be accounted for (and I guess those two in Tennessee, as well as a few micros, for the completists in the crowd)

barturtle
06-07-2007, 20:27
Betty Jo said that the fermentation takes 4 to 7 days. Is that the norm? If that is so it must be a very vigorous ferment which might go a long ways toward explaining why it is rarely contaminated.

Anyone know how much yeast is added to the beer?

Ed

I know there is a "recipe" based off of actual process in Regan's Bourbon and other Fine American Whiskies, but my copy is about 800 miles away right now...anyone else wanna look this up?

barturtle
06-07-2007, 20:31
The people with closed fermenters chose them so they would be ready to capture the carbon-dioxide by-product if it ever becomes necessary or desirable to do so.

This seems reasonable, and BT for sure, even though the fermenters are open, does have a ventilation system that draws the CO2 from right below the rim of the fermenters...otherwise the room would fill with the gas and walking in would suffocate you(at least that's my take on it.)

cowdery
06-08-2007, 12:41
A "short beer" fermentation is 3-4 days. A "long beer" fermentation is 6-7 days. The result is the same. The timing differences have to do with still scheduling.

nor02lei
06-11-2007, 12:55
Okay so it now stands at:

Open:
Four Roses
Buffalo Trace
Wild Turkey
Makers Mark
Woodford Reserve


Closed:
Jim Beam
Heaven Hill
Barton

That just leaves Brown Foreman to be accounted for (and I guess those two in Tennessee, as well as a few micros, for the completists in the crowd)

Brown Formans is closed and made of steel.

Leif

cowdery
06-11-2007, 16:56
The 36 fermenters at Jack Daniel's were covered about ten years ago.

jeff
06-11-2007, 19:14
The 36 fermenters at Jack Daniel's were covered about ten years ago.

Did they have a specific reason for doing so, or was it a simple renovation/remodel?

cowdery
06-11-2007, 23:08
I don't know for sure but I suspect they took advantage of some scheduled work to get it done. The rationale seems to be just to be ready in case capturing the CO2 becomes necessary or desirable.

mozilla
06-20-2007, 21:17
Buffalo Trace has two closed fermenters. As far as Four Roses they have stainless and cypress tanks.
BT also purchases thier yeast and Four Roses makes all five strains in house. BTW, one of them is fruity. This might account for that flavor profile in thier product. Also, I had a chance to taste the fruity yeast in the fermenter....it tasted great, good enough to bottle and drink on sight.
I posted pics of BT, FR and Bartons facilities in the tours section.
Jeff Mo

TBoner
06-20-2007, 22:03
Brew Like a Monk, by Stan Hieronymus, has an excellent discussion of the differences between open and closed fermenters in producing Belgian Trappist ales. In essence, Gary's assessment upthread of the differences between the two is in keeping with the comments in the book. However, both yeast strain and fermentation temperature play a bigger role in the finished product (as does the amount of yeast pitched - a smaller colony of yeast has to work harder in the earlier stages of fermentation, producing both more fruity esters and more fusel alcohols).

It's interesting to read descriptions of various beer and wine yeast strains and their fermentation character. There are yeast strains that specifically promote ester production or phenolic flavors and aromas (e.g. cloves), of course, but also strains that, based on the literature provided by yeast banks and on my personal experience, produce nutty flavors, mineral character (interesting to note that many UD products seem to exhibit a mineral character as discussed by Gary and others), vinous notes (even in beer yeasts used to ferment barley and not grapes), tartness, and oak/wood notes. Of course distillation probably mitigates these effects to a large extent, but I do wonder how much the yeast affects the finished product.

While I know the yeast strains used by distilleries are to some extent originally wild yeasts, and that they are optimized to produce maximum alcohol and not necessarily to yield a pleasant fermented beverage on their own, it would be interesting to brew a beer with the strain from a distillery and see what common character shows through between the beer and their whiskeys.

Oh, by the way, I just think the idea of recapturing the CO2 for other uses is cool. I have met a guy in a brewing forum who actually devised a way to recapture CO2 from his fermentation and use it to force carbonate his beer in soda kegs.

fussychicken
06-24-2007, 10:03
When the yeast works at the top (and I understand most bourbon distillers use top-ferment yeasts), it has to be skimmed off or the liquid drained from under it.

Interesting post Gary! However, it opens up all new questions for me. :)

What is done with this yeast after it has been used? Is it all used up at this point? If so, what is done with it? Or can it be reused?

How much do you think ends up in the beer anyway? Surely you couldn't perfectly separate all of the yeast out of the beer could you? I would think this could also affect the taste as well, correct?

If yeasts are either top or bottom, how can you make sure they they are exposed to all of the mash in a huge tank? Does mash fall or rise after some of it has been converted to alcohol?

Sorry for all the questions, but I have never seen any discussion for any of them. I would think that they are all important topics when it comes to making a good bourbon.

Gillman
06-24-2007, 13:14
Yes, thanks, and I should add I am not a homebrewer (although I would like to be), but simply have gained knowledge over the years by reading. I did however I attend a craft beer ale brewing once, I worked in the operation from mashing to fermentation stage. This was during a weekend at the former Newman brewery in Albany, NY.

The yeast whether top or bottom type (and there are gradations and hybrids) in fact works in the brew, in the center of it. As it completes its work, in top-fermentation (ale brewing at ambient temperature), the yeast collects at the top of the beer. In bottom ferments (for lager), it flocculates and sinks to the bottom, assisted by the colder temperature at which bottom yeasts work. (Think of how the sediment in a pond sinks in colder weather and the pond becomes more clear).

Some people think the distinction is largely historical, but it is maintained by many brewers I think to this day, i.e., that some yeasts work better at warmer temperatures and will generally rise to the top, while others work better at colder temperatures, and therefore it is valid to view them as two types (of the general yeast genus, which by the way is a type of fungus). Also, classic top yeasts do not convert as many sugars as bottom yeasts, so ales tend to be sweeter (but I am speaking broadly).

In distilling, you want as much sugar consumed as possible, to raise the yield, so one would think bottom yeasts would be the norm, but this is not my understanding. Maybe the distillers want the estery flavors that top-ferments produce. Maybe it is more a matter of tradition.

There are fixed ratios for how much yeast to add to a given amount of wort, and each brewer works out his own approach and refinements.

Excess yeast (and there is a lot usually) can be processed by industry for dried yeast for breadmaking and for other commercial uses. I don't know if whiskey distillers sell excess yeast or process it for such uses. Some distillers used to make commercial yeast for a broad variety of purposes, e.g., Fleischmann, as an adjunct to the distilling business.

Gary

adirondack
06-25-2007, 01:37
Jeff, being new here, can I just say that your icon made me crack up. kudos! (now I will read the thread, sorry for the interruption).

TBoner
06-25-2007, 06:01
Just a few addendums to what Gary posted above. Because yeast grows and reproduces in colonies, there is usually live yeast mixed in with the dead yeast, meaning "used" yeast can be harvested and "washed" for use in a future batch. This is frequently done in brewing on every level, though usually brewers/distillers will want a fresh colony of their yeast strains after a few generations to preserve its purity.

Also, while ale yeasts tend to leave a fuller-bodied beer behind, they are not necessarily less attenuative in terms of eating sugars (Gary, I know you said you were speaking broadly on this point). In fact, the Belgian ale strains are notoriously hungry, and will eat even some complex sugars that other yeasts won't touch.

Finally, while there are fixed ratios for pitching yeast into wort, some beer brewers when making a particularly fruity style will "underpitch," causing the yeast to produce esters during the difficult reproduction it goes through in the early stages of fermentation (a good way to ruin a lager, by the way). It's possible some distillers would do this to produce a fruitier character, as well, regardless of the fruitiness of the yeast they're using.

T47
06-28-2007, 21:59
Maybe slightly off topic, did anyone see the History Channelís Modern Marvel show Distilleries 2? I found it very interesting. They did quite a good story on Absinthe. There was a story about a restaurant/bar in Idaho that is distilling and bottling it's own rum. No aging however. Anyway, I thought it was interesting. Not nearly as in-depth as this thread, but a nice over view.
They had some ex-moon shiners (not sure how ex they really are) who were some real characters.
Hope this is not old news.

:toast:

fussychicken
07-06-2007, 19:52
Thanks for the good posts Gary and Tim. Maybe you guys can help me out with one more as I think it may be related to your posts:


A "short beer" fermentation is 3-4 days. A "long beer" fermentation is 6-7 days. The result is the same. The timing differences have to do with still scheduling.

How is this modulated? Based on how much yeast you initially put in?

TBoner
07-06-2007, 19:57
Well, I'm not sure exactly how different distillers would modulate that, but it could be done by the amount of yeast pitched, the temperature of the fermentation (generally, warmer=faster), use of extra yeast nutrient (not incredibly reliable), additional oxygenation of the mash (in beer terms, the "wort") to increase speed of fermentation, or the amount of sugar in the mash/wort (which likely, in distilleries, would always be the same).

Edward_call_me_Ed
07-08-2007, 09:03
Well, I'm not sure exactly how different distillers would modulate that, but it could be done by the amount of yeast pitched, the temperature of the fermentation (generally, warmer=faster), use of extra yeast nutrient (not incredibly reliable), additional oxygenation of the mash (in beer terms, the "wort") to increase speed of fermentation, or the amount of sugar in the mash/wort (which likely, in distilleries, would always be the same).


Yeast pitched and temp could be the explaination. On the other hand, maybe they just keep it sitting around till they get around to it.

Anybody know for sure?

Ed

cowdery
07-08-2007, 22:23
It's done by controlling the temperature, which is done by pumping cool water through pipes that line the insides of the fermenter tubs. They may also use less yeast for the longer fermentations but I don't think so. I think it is all done with temperature control. Good question, though. I try to remember to ask that next time I get a chance.

Most distilleries just have one type of set that goes about four days.