TOTM, 6/07: Fermentation

[jeff]

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]

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]

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]

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]

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]

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]

Barton = Closed

Woodford = Open

Don't know the rest

[Gillman]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

Four Roses makes notably fruity whiskeys.

Gary

[bobbyc]

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]

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]

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]

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]

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]

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]

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.)