SG question at crush

[wood1954]

I crushed my grapes yesterday and the Sg today is 1.092. Which is about 12% alcohol. As the must ferments will the alcohol level increase as the sugar and carbs in the skins get metabolized?
Or, will it go down as the must has lots of non sugar solids In it right after crush. What think you?

 

[Ajmassa]

12% abv “potential alcohol” unofficially. That number is based on a 1.000 endpoint (which 1.092 to 1.000 technically would be 12.5%)
But in reality if you ferment dry it’ll be under 1.000, say .993 possibly. That gives you a 13.5%abv.

and regarding your question if the SG were to move while macerating with skins and juice it’s going to move up as more goodness is released into the juice. Don’t think I ever heard it drop before fermenting. Only increase.
Just relaying info I’ve learned. Can’t state if this is scientific fact or not tho

 

[mainshipfred]

12% abv “potential alcohol” unofficially. That number is based on a 1.000 endpoint (which 1.092 to 1.000 technically would be 12.5%)
But in reality if you ferment dry it’ll be under 1.000, say .993 possibly. That gives you a 13.5%abv.

and regarding your question if the SG were to move while macerating with skins and juice it’s going to move up as more goodness is released into the juice. Don’t think I ever heard it drop before fermenting. Only increase.
Just relaying info I’ve learned. Can’t state if this is scientific fact or not tho

Agree, I don't add the yeast until at least the following day, sometimes 2 and more sugars will release from the fruit. I'll take a gravity reading at crush but what I record is prior to inoculation. AJ is also correct in the charts give you the ABV at 1.000. I use the formula (IG-FG)x131.

 

[wood1954]

Thanks guys, I was hoping for a lower alcohol wine this year.

 

[Kraffty]

My understanding is that you can adjust the must back with acidulated water to lower the ABV. No clue how much you'd water down your wine though.

 

[JoP]

12% abv “potential alcohol” unofficially. That number is based on a 1.000 endpoint (which 1.092 to 1.000 technically would be 12.5%)
But in reality if you ferment dry it’ll be under 1.000, say .993 possibly. That gives you a 13.5%abv.

and regarding your question if the SG were to move while macerating with skins and juice it’s going to move up as more goodness is released into the juice. Don’t think I ever heard it drop before fermenting. Only increase.
Just relaying info I’ve learned. Can’t state if this is scientific fact or not tho

AJMASSA,
It makes sense for SG to increase during maceration, but what about after pressing and yeast addition?
I just started fermentation on a Muscat Blanc juice only and initial SG was 1.100 (23.7BRIX)
After pitching the yeast, in the first 15 hours SG increased gradually to 1.117 (27.6 BRIX)
Three hours later it went down to ISG of 1.1,
Last year happened also, with different yeast.
How can this be explained?
Thanks,

John

 

[stickman]

Bubbles collecting on the hydrometer possibly.

 

[JoP]

Bubbles collecting on the hydrometer possibly.

Possible, but I'm not convinced yet.
The hydrometer is a wireless Tilt floating in the fermenter all the time, need to monitor closer next time.
Thanks
John

 

[stickman]

It's very possible CO2 is an issue for a short time early as the fermentation gets going. Below is from the Tilt site.

Q. How do bubbles from CO2 affect the Tilt?


A. We recommend putting the Tilt in your beer prior to pitching yeast, this will ensure any bubbles will not affect initial readings. Bubbles from dissolved CO2 may cause higher than expected readings for a short time if placed in an active fermenting brew. However, this can be sped up if washed with alcohol (i.e. Everclear).

 

[GR!]

Could it be the start of the fermentation?

 

[JoP]

It's very possible CO2 is an issue for a short time early as the fermentation gets going. Below is from the Tilt site.

Q. How do bubbles from CO2 affect the Tilt?


A. We recommend putting the Tilt in your beer prior to pitching yeast, this will ensure any bubbles will not affect initial readings. Bubbles from dissolved CO2 may cause higher than expected readings for a short time if placed in an active fermenting brew. However, this can be sped up if washed with alcohol (i.e. Everclear).

Stickman, thank you for the feedback.
Before your reply, I just emailed to Marcus from Tilt about this., but you just found the answer, thank you!
John