TOTM, 6/07: Fermentation

[cowdery]

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]

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]

The 36 fermenters at Jack Daniel's were covered about ten years ago.

[jeff]

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]

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]

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]

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]

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]

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]

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]

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]

Maybe slightly off topic, did anyone see the History Channel’s 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]

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]

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]

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]

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.