Alcohol content questions

[perrypainter]

I had a couple concerns regarding controlled alcohol percentage:

First, I was under the impression that beer yeasts have been cultured and engineered to die off in certain alcohol-rich environments. So...does anyone know what this percentage is for white labs yeast?

Also, to reach this potential volume, is there a simple calculation for pounds of grain for mash to use/extract syrup?

Lastly, is there a way to achieve a more vigorous and longer fermentation?

 

[Cape Brewing]

There is a lot here...

I had a couple concerns regarding controlled alcohol percentage:

First, I was under the impression that beer yeasts have been cultured and engineered to die off in certain alcohol-rich environments. So...does anyone know what this percentage is for white labs yeast?

It depends on the specific yeast. White Labs produces a huge range of different yeasts and they will all vary a bit in their tolerance. You can look on White Labs' website and they provide a short summary (including abv tolerance) for each yeast they make.

Also, to reach this potential volume, is there a simple calculation for pounds of grain for mash to use/extract syrup?

I am not sure whqt you're asking here... Do you mean is there a calculation that will tell you what to expect for abv out of a given amount of grain? Any brewing software will do this for you very quickly and easily.

Lastly, is there a way to achieve a more vigorous and longer fermentation?

i guess I would ask why you want more "vigorous" or "longer fermentation"? Again... Not sure what you're driving at. You should simply be looking for HEALTHY fermentation and that doesnt neccessarily mean vigorous or long. Healthy fermentation can be helped by good sanitation, appropriate levels of fermentabl sugars in the wort for that style, healthy viable yeast pitched at the proper rates, proper fermentation temps for the style and the yeast, good aeration providing proper oxygen levels. If with all of these thigs dialed in perfectly though... Depending on the yeast and the beer you're making, fermentation may not be vigorous or long... And that wouldnt be a bad thing at all.

 

[COLObrewer]

I had a couple concerns regarding controlled alcohol percentage:

First, I was under the impression that beer yeasts have been cultured and engineered to die off in certain alcohol-rich environments. So...does anyone know what this percentage is for white labs yeast?

Also, to reach this potential volume, is there a simple calculation for pounds of grain for mash to use/extract syrup?

Lastly, is there a way to achieve a more vigorous and longer fermentation?

There are too many variables to track concerning fermentation, most every fermentation will be different in some way (unless you live on a planet with no moon in a chamber with controlled barometric pressure, in a vaccuum with exact temperature and humidity control, suspended with zero vibrations, etc, etc).

There are certain yeasts that go dormant at different levels of alcohol, they don't neccessarily die, for instance the yeast I cultured in this thread:
https://www.homebrewtalk.com/f163/can-i-culture-yeast-juniper-berries-169156/
Stopped producing at 15%, the sample I tested that had sugar to go to 20%+ also stopped at 15%, some are tollerant to 12%, 8%, etc, you just have to look at the details regarding the specific yeast you're using, you should be able to discern what % any White Labs product is good for.

As far as "controlling" alcohol percentage, you simply formulate your brew with the amount of fermentable sugar it takes to achieve the desired alcohol %, profile,etc.

I hope this answers some of your questions as I'm not sure exactly what you are asking.

Brew on my friend

 

[Captain Damage]

1 - Each strain of yeast, regardless of the manufacturer, will have a different alcohol tolerance. Check the manufacturer's website for this information re your specific strain. Most strains are good until you get over 7-8% abv afaik.

2 - BeerSmith tells me that if you replace your grain with 62.5% DME by weight then you get roughly the same gravity.

3 - These are completely dependent on the qualities of the wort, strain of yeast and temperature. I'm not sure I understand your question. Are you trying to get more alcohol out of a given wort/yeast combination? The way to get more alcohol is to add more fermentable sugars to your wort - either more malt or just plain old sugar. When the sugar is fermented, it's done. You can't tease more alcohol out of it after that. A certain percentage of the sugars in a given wort will be unfermentable by any given strain of yeast. Some strains are more attenuative than others, meaning there are a few more sugars they can ferment. Again check the manufacturers' websites. They list the average attenuation by percent.