Yeast in the wash/boiler charge

[Hillbilly Popstar]

So...
I have always felt it was most beneficial to have a wash that was as clear as possible.

In the past, early in my exploration into this hobby, I have ran muddy looking washes and swear I remember getting distillate that had a yeast flavor I didnt like. Likker tasted like bread. One time I even got a scorch from burnt yeast. But scorching aside, I remember tasting off flavors (not scorching), just yeasty and bready off flavors that I didnt care for.

I was reading an article shared by Cayers the other day.
https://www.bostonapothecary.com/from-f ... de-simple/
This article suggests that having dead and/or dormant yeasts in the boiler can generate ester production.

But maybe not all esters are good esters?
Or maybe the particular esters produced from hot yeast in the boiler are only beneficial to certain types of likker?

So now I'm curious. How much yeast is beneficial to leave in the boiler, if any... and when is it beneficial?
Also, should there there be certain precautions taken, like in how you run the still, or how you treat the wash, in order to maximize desireable flavors and eliminate undesirable flavors?

[cayars]

Keep in mind what the author does say "Many of the ideas are speculative."
#2 & #3 are good points to understand. #3 is part of the reason for rerunning feints.

"Esters are very volatile and their fatty acids precursors are also volatile, even though they have boiling points higher than water. Many fractions of the distillation process are recycled into subsequent runs to give more opportunity for esterification. The recycling phenomenon means that you cannot just produce one batch of product because the final distillate is actually the product of many integrated batches."

The author does mention "off flavors" that can happen for the use of yeast.
Freeze distillation is something I've done in the past and did end up with full flavors. This is something I want to explore this winter when freezing comes for free.

The author says fusel oils do not benefit from being recycled and are often only desired in low concentrations. This almost makes it sound like it would be beneficial to not recycle tails but only heads.

I'm going to have to read this a few more times. So much information and ideas present.

[still_stirrin]

So...an article shared by Cayers the other day: https://www.bostonapothecary.com/from-f ... de-simple/

But maybe not all esters are good esters? Or, maybe the particular esters produced from hot yeast in the boiler are only beneficial to certain types of likker?

So now I'm curious. How much yeast is beneficial to leave in the boiler, if any... and when is it beneficial?

Also, should there there be certain precautions taken, like in how you run the still, or how you treat the wash, in order to maximize desireable flavors and eliminate undesirable flavors?

That article takes a somewhat “holistic” approach towards esterfication...a lot of ideas, but not a lot of facts. But, it is noteworthy that the ferment plays a roll in the potential for ester development, and possible whether or not those esters are desireable in the spirit. Brandy, eau de vie, rum and other “sweet spirits” often benefit from ester development post fermentation.

So, “what you make” matters. And when aiming for enhanced ester formation, process matters. Reduction of the acids into esters is catalyzed by elevated temperatures, so as discussions here have presented, ester development benefits from pre-heating the must, wash, or mash during the early phase of the distillation process. Similarly, ester development will occur post distillation if the product is acidic and “time aged” in a cask where the spirit undergoes thermal cycles over time. Certainly, the yeast cannot be blamed for the esters developed in the cask.

If you’re interested in the pursuit of the esterfication science, there are a few treatise on it on this site. A search should produce a few threads worth your time.

If instead, you’re trying to reduce the “yeasty” and “bread-like” flavors from your spirit, it would help to understand better how you got those qualities and whether or not they’re desireable to your paradigm....ie, “what did you make and what ar you trying to emulate?”
ss

[Hillbilly Popstar]

Keep in mind what the author does say "Many of the ideas are speculative."
#2 & #3 are good points to understand. #3 is part of the reason for rerunning feints.

"Esters are very volatile and their fatty acids precursors are also volatile, even though they have boiling points higher than water. Many fractions of the distillation process are recycled into subsequent runs to give more opportunity for esterification. The recycling phenomenon means that you cannot just produce one batch of product because the final distillate is actually the product of many integrated batches."

The author does mention "off flavors" that can happen for the use of yeast.
Freeze distillation is something I've done in the past and did end up with full flavors. This is something I want to explore this winter when freezing comes for free.

The author says fusel oils do not benefit from being recycled and are often only desired in low concentrations. This almost makes it sound like it would be beneficial to not recycle tails but only heads.

I'm going to have to read this a few more times. So much information and ideas present.

Yes, but I am much more concerned with yeast and other suspended solids in the boiler.

It frustrates me that the article states that having yeasts in the boiler during distillation can both create desired esters and unwanted off flavors, but the article states very little about how to nurture or mitigate either phenomenon.

Which is kinda the point StillStirrin just made.

[Hillbilly Popstar]

If you’re interested in the pursuit of the esterfication science, there are a few treatise on it on this site. A search should produce a few threads worth your time.

If instead, you’re trying to reduce the “yeasty” and “bread-like” flavors from your spirit, it would help to understand better how you got those qualities and whether or not they’re desireable to your paradigm....ie, “what did you make and what ar you trying to emulate?”
ss

Well, I mostly make corn mash or sweet feed gumball heads.

It would be quite beneficial to know exactly where the yeasty/bready flavors are coming from. I just assumed it was too much yeast in the boiler. But it seems you're suggesting there could be other culprits?

I am mostly curious about under what conditions and in what amounts having yeast in the boiler could actually be beneficial and what sort of benefits should we expect?

[still_stirrin]

Well, I mostly make corn mash or sweet feed gumball heads.

It would be quite beneficial to know exactly where the yeasty/bready flavors are coming from. I just assumed it was too much yeast in the boiler. But it seems you're suggesting there could be other culprits?

Well, if your “corn mash” is a full grain mash (not a UJ-style sugar wash with cracked corn added), then I’d suppose the yeasty an bread-like flavor is from unconverted starches in your wash. And likewise, when making a gumball-head with more grain mix on a sugar ferment base, the flavors in the wash hold a lot of starches which carry to the boiler.

And I’d speculate that you get a lot of foaming in the boiler as well which can actually produce some “puking” which will entrain the potential for off flavors into your spirit.

I am mostly curious about under what conditions and in what amounts having yeast in the boiler could actually be beneficial and what sort of benefits should we expect?

Again, I speculate that there is little “benefit” to yeast in the boiler because of the greater risk of “the consequence” of it. There would always be the risk of a scorch because of the solid matter. And that will create a taste detectable at very low flavor thresholds and it is very, very difficult to eliminate those flavors (and aromas, which is much more common) once encountered.

And restating my previous point, if you truly want to develop more esters post ferment (many esters are produced during the ferment any way), then warming the wash and holding the temperature for a duration (well below boiling point, however) will augment the esterification development. But, it does require that the wash’s pH fall within the range for this process.

Again, do a search for “esterification” to learn more.
ss

[Hillbilly Popstar]

This post isnt about how to achieve esterification.

It's about yeasts in the wash. How much is allowable and how much is unacceptable, and what, if any, benefits might there be.

I see you are of the "wash needs to be clear" school of thought. But that's highly debatable. Many craft and commercial distillers do distill murky washes, as do many hobbyists. This is evident here,
viewtopic.php?f=15&t=29504

So I thought it would be beneficial to have a thread discussing/debating the merits of the differing protocols.

[Hillbilly Popstar]

Here's another thread in which opinions (many from very reputable members of our community) vary wildly.
viewtopic.php?f=1&t=57057

[cayars]

I wouldn't say the article was about yeast in the boiler per say. It was only one of many things mentioned.
There is little if any scientific proof behind the article, just speculation and observation which is what a lot of threads around here are. Just one guys opinion.

I do find a lot of the ideas with merit and have tried some and do find it a good read for ideas.

If you are interested in the yeast in the boiler, setup and do some trials. For example rack off your wash to get it clear. Then capture a good amount of lees. You can then run a few gallons clear, then with X amount of lees added, then 2X lees added, etc. Run them all the same with a slow ramp up to heat and on the slower side to get full affect.

At least this way you can see if there is any notable impact on your setup and environment.

[Hillbilly Popstar]

Currently doing exactly that right now.

My last corn mash still ended up rather thick after squeezing the grain and letting it rest for a day.

But first I got about 6 gallons of cleared wash that I racked off the top.
So I am gonna run each and see the difference.

Heating up really slow to avoid a scorch. This is gonna be a long strip.

Also, I never said that the article was about yeast in the boiler. But it does mention it and that is what this thread is about.

[StillerBoy]

On the subject of yeasty smell and or flavour, what I've come to do with the sugar wash, and that is with both bread and 1118 yeast, is to properly clear it..

My process now is to allow the wash to start clearing itself on it own.. at that stage, I rack it into another fermenter, degas it very well and add two part clearing agent used in the wine making process, and allow it clear completely which takes about 7 - 10 days.. then strip it at a slower pace that I normally strip at..

The finished spirit has no yeasty smell or flavour carried over.. in comparison, a friend who does the same wash recipe and process, but not the clearing step, and has both the smell and flavour carry over when compared, using basicly the same stripping process and equipment..

Mars

[Hillbilly Popstar]

I find sugar washes very easy to clear.
Mine settle into a dense yeast cake a few days after fermentation is done.

It's the all grain or partial grains that I am putting more time into processing.

[Hillbilly Popstar]

So you mean to tell me, that whilst discussing something nearly all craft and commercial distillers practice, nobody has a shred of input on how or why it could be beneficial or detrimental on the hobby level?

All I've gotten is, "it could scorch" and everyone who seems do it with out it scorching (mine scorched yesterday btw) says they dont notice any bad flavors.

[cayars]

Personal opinion, but I'd think it would be impossible for anyone to say what YOUR verdict would be or what mine would be. So many factors come into play. The grain bill and source of grains, yeast used, the ABV of the mash, pH of mash, nutrients that were present, nutrients that didn't get used by yeast and still present, the temperature of the mash, on/off grain, amount of unfermented sugars present, proteins present, acids present, days of ferment, allowed to clear, etc...

On one batch the yeast being present (in some number) could be quite pleasing and add nice tastes/aromas and the next batch with just the slightest of change could produce off-tasting aromas. Short of fermenting a large batch and harvesting the yeast to be able to add back in some controlled proportion it would be hard to even test. Doing it this last way would give you a control for THAT BATCH to know...

[Fredistiller]

Not so long ago I read an article about this topic. In Cognac, the use of yeast in the still is commonly used. It would help to develop that typical "rancio" taste that you can find in some older cognacs. But it takes years for the "yeast given tastes" to develop into something nice. So they don't use yeast in the still for the VS or *** type for example, because this would give unwanted flavors.