Yeast alcohol production/tolerance

[superstock]

A few months ago I bottled a JAOM which was as per the recipe with the exception of the yeast. I used Tandaco Bakers Yeast instead of Flieshmans. The OG was 1145 and the FG was 1040 for a ABV of 14% which seemed very high for a bakers yeast,so I did a little experiment. I made a brew---
6L Woolies Apple & Blackcurrant
500gms white sugar
1/2 cup strong black tea
1/2 Tspoon yeast nutrient For an OG1086
I then split the batch in 2 and fermented one with Tandaco Bakers yeast & the other with Brigalow Brewers yeast (I had contacted Brigalow and they said that that was the yeast that they used in their cider kit and it had an alcohol tolerance of arround 6.5%)
I left them to ferment for 8 weeks to give the yeast every chance to ferment out.
Then I checked the FGs
The Bakers yeast fermented out at 999 giving a ABV 11.66%
The Brigalow brewers yeast fermented out at 1002 giving a ABV 11.26%

Am I calculating wrongly? These ABVs seem very high for what are usually considered low alcohol yeasts.

 

[indica86]

Seems correct to me.

 

[boonchu]

Can also be to do with the amount of yeast pitched / litre, high pitching rates can help to drive the abv higher.

 

[simchop84]

A bit off topic but is using bakers yeast a common thing to do or where you just experimenting?
Cheers

 

[Dunkelbrau]

I recently got wyeast Scottish ale (1728) up to 13.2%, it's tolerance is 12% on their website.

I do have a feeling yeast health and amount make a difference, look at that ghost deer from brew dog. 28% naturally fermented!

 

[mr_wibble]

A bit off topic but is using bakers yeast a common thing to do or where you just experimenting?

The JAO Mead recipe says (in no uncertain terms) that it is specifically designed to be made with bakers yeast.
So I'd guess this is why superstock used it in the experiment.

 

[superstock]

The reason I raised this matter harks back to my JAO mead. Most of what I have read about this recipe says around 6-8%ABV almost drinkable straight away, sweet with a citrus background. The only changes I made to the recipe was to convert to a 5L volume and change the yeast. What I brewed was beautifly clear between the yeast and the floating orange/raisen. I siphoned off about 3.8L of golden, citrusy, rocket fuel, which SGd out at 14%. Now, I'm sure that my grandson will thank me when he opens one of these 20 years from now and I was curious if anyone else has had the same result.
Combine this with the cider experiment and it appears that some supposedly low yield yeasts are very underrated.

 

[punkin]

I think a rating of yeast versus osmotic pressure due to alcohol is not a deadline that the yeast will all suddenly die and ferment will stop. It means that a ferment is good up to that point, that the yeast remain healthy, vialble and able to reproduce and that they will perform as desired.

Go significantly above this figure and you get unhealthy mutations, loss of function etc rather than just an end to fermentation.

So take it as a recommendation when designing fermentations rather than a tool for curcumventing pastuerising or other sweetning tactics.