Science of yeast. Exactly how much sugar is too much?

[DWelsh]

After loads of research I still am unable to find out specifically how much sugar is too much in a wash. I've always used one pound of sugar with 1.5 teaspoons of yeast nutrients for every gallon of water. The results always taste good after distilling. I have read many recipes which use two lbs of sugar for every gallon and herd of people using more. I have read that too much sugar can actually kill the yeast, but how much is too much? I'm interested to hear anyone's detailed experiences with this.
I did an experiment and put 2.75 lbs of brown sugar in a one gallon wash. According to my hydrometer, the potential alcohol by volume for that much sugar was only 15%, so I'm curious to find out why what should be too much sugar didn't give an excessively high potential ABV. I'm using a mixture of 2/3 bakers yeast and 1/3 champagne yeast. I'm still waiting to see how it turns out since I only made it today. I'll post the results after its finished fermenting and again when I distill it.

*This is just an experiment to see EXACTLY how much sugar will start to kill off yeast in a sugar wash. If anyone out there is a yeast expert, I'd like to hear as much as you know.

[der wo]

2lbs per gal will be the maximum for bakers or wine yeast. With port wine yeast perhaps 2.3lbs. Turbo yeast 2.7lbs.
What is the FG on your 2.75lbs experiment?
The FG should reach for 2lbs 0.950 and for 2.7lbs 0.980. If it's higher, too much sugar is not fermented (too much sugar for the yeast or problems with pH or nutrients or temperature).

[still_stirrin]

Baker's yeast can actually "tolerate" up to 12-14%ABV potential before attenuating. However, is will be extremely stressed, producing many off-flavor constituents ("yeast poop" is what some call it).

The point being, "why push the yeast to the extremes"? You would be better off shooting for 8%ABV potential and make a ferment that tastes good. Then, the distilled product will have a nice flavor and less distasteful by-products, thereby reducing your good hearts. As said many times here, "quality over quantity".

Your experiment shows all the signs of a rookie endeavor...go for it...but remember, you were warned. Some learn best "the hard way".

Be safe. Be responsible. And be discrete.
ss

[der wo]

I thought, he thinks about it more theoretically.

And he will loose time. A bakers yeast wash 14% will need double than a 10% to ferment dry.

But in my experience a tpw with added nutrients 13% tastes same than the same wash with sugar only for 10% after stripping. Without the nutrients the fermentation of the 13% wash stalls before the end and the taste is worse.

[DWelsh]

2lbs per gal will be the maximum for bakers or wine yeast. With port wine yeast perhaps 2.3lbs. Turbo yeast 2.7lbs.
What is the FG on your 2.75lbs experiment?
The FG should reach for 2lbs 0.950 and for 2.7lbs 0.980. If it's higher, too much sugar is not fermented (too much sugar for the yeast or problems with pH or nutrients or temperature).

I only made it yesterday so I will post the FG next week.

[DWelsh]

Baker's yeast can actually "tolerate" up to 12-14%ABV potential before attenuating. However, is will be extremely stressed, producing many off-flavor constituents ("yeast poop" is what some call it).

The point being, "why push the yeast to the extremes"? You would be better off shooting for 8%ABV potential and make a ferment that tastes good. Then, the distilled product will have a nice flavor and less distasteful by-products, thereby reducing your good hearts. As said many times here, "quality over quantity".

Your experiment shows all the signs of a rookie endeavor...go for it...but remember, you were warned. Some learn best "the hard way".

Be safe. Be responsible. And be discrete.
ss

I understand that this will not be a drinkable distillate. I explained that this was JUST an experiment to see how much sugar yeasts can withstand before they are killed by it. This is not an endeavor to produce quality with quantity and, as I also explained, far from how I ever make sugar washes that are drinkable. I am interested in the biology of the yeasts here.

[DrMalt]

The point being, "why push the yeast to the extremes"? You would be better off shooting for 8%ABV potential and make a ferment that tastes good. Then, the distilled product will have a nice flavor and less distasteful by-products, thereby reducing your good hearts. As said many times here, "quality over quantity".

Your experiment shows all the signs of a rookie endeavor...go for it...but remember, you were warned. Some learn best "the hard way".

Be safe. Be responsible. And be discrete.
ss

+1

An easy ferment (for the yeast) makes more usable and better tasting product. Why bother spending time and money on stuff you throw away or have to run several times to make useful? Even doing it to make fuel doesn't make sense when you have to use more energy to clean it up.

[rgreen2002]

Baker's yeast can actually "tolerate" up to 12-14%ABV potential before attenuating. However, is will be extremely stressed, producing many off-flavor constituents ("yeast poop" is what some call it).

The point being, "why push the yeast to the extremes"? You would be better off shooting for 8%ABV potential and make a ferment that tastes good. Then, the distilled product will have a nice flavor and less distasteful by-products, thereby reducing your good hearts. As said many times here, "quality over quantity".

Your experiment shows all the signs of a rookie endeavor...go for it...but remember, you were warned. Some learn best "the hard way".

Be safe. Be responsible. And be discrete.
ss

I understand that this will not be a drinkable distillate. I explained that this was JUST an experiment to see how much sugar yeasts can withstand before they are killed by it. This is not an endeavor to produce quality with quantity and, as I also explained, far from how I ever make sugar washes that are drinkable. I am interested in the biology of the yeasts here.

+1 for curiosity. “To ask the 'right' question is far more important than to receive the answer. The solution of a problem lies in the understanding of the problem; the answer is not outside the problem, it is in the problem.” -Jiddu Krishnamurti

This problem will cost little time...and about $2 in materials... cheap in the grand scheme of things.

That being said, here is a little info on yeast (your specific question is not answered here...sorry): http://www.yobrew.co.uk/fermentation.php" onclick="window.open(this.href);return false;" rel="nofollow

For everyone else... This is some great information about fermentation and troubleshooting. All stuff you can find scattered through the pages of HD in one place. http://www.yobrew.co.uk/stuck.php" onclick="window.open(this.href);return false;" rel="nofollow
Interestingly this page states :"Sugar (not more than 1 KG per 4.5 litres or 2 lb per gal)" but I have no idea where this data comes from

[raketemensch]

Chris White has a great book called Yeast. It's one of those books where you can learn a little very quickly, but learn a ton the more you read it.

[Kegg_jam]

I guess a better experiment would be how much sugar ('yeast poop') can you take.

Seriously though, what the yeast can take is sort of irrelevant if you can't drink the final product.

So yeah, find your upper limit for your protocol. Nothin wrong with that. I think I can get a pretty clean 12%. But that's just me.

[DWelsh]

I have another question for anybody out there. There are yeasts that are advertised to achieve up to 20% ABV in just 5 days. Has anyone used these before? What has your experience been? I've seen that half of these yeasts are turbo yeasts, which I am well aware taste awful. But I've seen some that are without nutrients and probably take a bit longer. Also, which yeast is everyone's favorite? I'm about to do a large wheat mash along with a molasses rum wash. I've always had good results with bread yeasts, but I'm just curious whats best in other people's opinions.

[rgreen2002]

I have another question for anybody out there. There are yeasts that are advertised to achieve up to 20% ABV in just 5 days. Has anyone used these before? What has your experience been? I've seen that half of these yeasts are turbo yeasts, which I am well aware taste awful. But I've seen some that are without nutrients and probably take a bit longer. Also, which yeast is everyone's favorite? I'm about to do a large wheat mash along with a molasses rum wash. I've always had good results with bread yeasts, but I'm just curious whats best in other people's opinions.

I've never used a turbo yeast but most here will tell you......don't...just don't (unless you're making rocket fuel or something not for sipping)
I've learned the hard way that bread yeast is great for rum (cheap, easy and works well)
Ive used a lot of EC-1118... It is a very SLOW yeast (even though it bills itself as fast) with a wide temperature tolerance and a theoretical yield of 18% EtOH (I've never gone there with it as I believe in off flavoring with stressed yeast as mentioned above)
I think others will be more experienced to help you with a choice for the wheat...

[Hillbilly Popstar]

Most brewers yeasts will advertise a plethora os stats about each yeast strain, such as: ideal temps, flavors and aromas imparted, ideal range of original gravity, and attenuation levels.

[greggn]

> Chris White has a great book called Yeast.

Thanks for the recommendation. I just picked this up ... looking forward to spending some time with it.

[greggn]

>This is just an experiment to see EXACTLY how much sugar will start to kill off yeast in a sugar wash.

It may just be semantics but it's not a matter of too much sugar will kill the yeast it's that too much sugar will result in too much alcohol which will kill the yeast. Again, maybe semantics but you may want to modify the premise of your experiment.

[cuginosgrizzo]

It may just be semantics but it's not a matter of too much sugar will kill the yeast it's that too much sugar will result in too much alcohol which will kill the yeast. Again, maybe semantics but you may want to modify the premise of your experiment.

It is not only the high alcohol percentage, but also the high osmotic pressure in the wash due to the sugars, that splits open the yeast cells, or makes it hard for the yeasties to digest sugars.

[der wo]

Yes, it is not only the alcohol, what kills the yeast, as cunigosgrizzo says.

And I don't think, he gets an exact result.
More sugar and the fermentation slows down. Even more, it will ferment slow and not finish dry. And yes, there will be a point, where not one yeast cell will start to work even with good aeration. And finally there will be one point, where each yeast cell dies.

Perhaps this is a good question:
From how much sugar not more alcohol will build?