Yeast attenuation

[Harbrook]

Hi..

Another beginner question that I hope you have the patience to answer.
I've brewed beer before but this is my first wine. I'm currently fermenting a Vineco Atmosphere Amarone.
I used the kit yeast which is EC-1118 and all is fermenting nicely.
I had a SG of 1.100 which was on the upper end of the kits target SG (1.080-1.100), The Target FG is 0.995 which gives a yeast attenuation of 105%
Is this possible, how can this figure exist? I'm sure I'm misunderstanding something...?
please excuse the basic questions, but I'm keen to learn and would like to get better at this.
I love my new hobby!
thanks in advance

 

[cpfan]

I haven't made any of these new Vineco kits but I assume that they are similar to the old Ken Ridge Showcase kits. They fermented down to .992 pretty regularly.

I'm not going to pretend to understand attenuation but it appears to be a measure of "the percentage of sugars yeast consume during fermentation". IMO, 100% attenuation is reached at .992 or even .990 not 1.000.

BTW, attenuation seems to be a beer brewing concept not a wine making concept.

Steve

 

[Johnd]

Hi..

Another beginner question that I hope you have the patience to answer.
I've brewed beer before but this is my first wine. I'm currently fermenting a Vineco Atmosphere Amarone.
I used the kit yeast which is EC-1118 and all is fermenting nicely.
I had a SG of 1.100 which was on the upper end of the kits target SG (1.080-1.100), The Target FG is 0.995 which gives a yeast attenuation of 105%
Is this possible, how can this figure exist? I'm sure I'm misunderstanding something...?
please excuse the basic questions, but I'm keen to learn and would like to get better at this.
I love my new hobby!
thanks in advance

The numbers are specific gravity units, .990 is considered completely dry, when 100% of the sugars are gone. The hydrometer measures the buoyancy of the liquid, which is affected by the amount of sugar dissolved in it, the higher the SG, the more sugar, the more alcohol that the yeast can produce. The specific gravity of water is 1.000, but alcohol is less dense than water, which is why the SG can get below 1.000. I can't tell you for certain that at .990 you have 0% residual sugars in the wine, but I've never seen one go any lower than .990. So, while fermenting down from 1.100 to .995 is a drop in specific gravity of .105, it's not 105%.

 

[BernardSmith]

Ale yeasts may be listed by attenuation but all the sugars in fruit are fundamentally fermentable so attenuation is not a wine maker's metric. We expect every yeast to be able to ferment a must down to below 1.000 (if water is 1.000 and alcohol is less dense than water then any fully fermented wine ought to be below 1.000 (unless there is a reason for the fermentation to cease above 1.000) )