WineXpert SG correction from grape skin pack

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Seke

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I started making the LE 14 Super Tuscan kit yesterday, and I am wondering about the contribution to the fermentable sugars from the grape skin pack.

Of course I know that the grape skin pack contains sugars which will gradually dissolve during fermentation. What I would like to know is how much, so I can make a reasonable correction to the SG in order to calculate the ABV.

When I measured SG after mixing the kit to the specified volume, but before adding the grape skin pack, I read 1.075. I then added the grape skin pack, stirred well again, and measured 1.081. After 24 hours, fermentation is well on its way, and I read 1.087.

I figure that if there is a known amount of sugar in the grape skin pack it should be possible to specify an SG correction. Any thoughts?
 
I started making the LE 14 Super Tuscan kit yesterday, and I am wondering about the contribution to the fermentable sugars from the grape skin pack.

Of course I know that the grape skin pack contains sugars which will gradually dissolve during fermentation. What I would like to know is how much, so I can make a reasonable correction to the SG in order to calculate the ABV.

When I measured SG after mixing the kit to the specified volume, but before adding the grape skin pack, I read 1.075. I then added the grape skin pack, stirred well again, and measured 1.081. After 24 hours, fermentation is well on its way, and I read 1.087.

I figure that if there is a known amount of sugar in the grape skin pack it should be possible to specify an SG correction. Any thoughts?

Well, I also did the LE Super Tuscan. My SG was 1.078 before adding the grape pack. It went up to 1.096 before it started decreasing. (I used a slow-starting yeast, BM45, which gives a little more time before the SG starts decreasing.) This delta_SG of 0.018 is in line with what I have observed in other kits, too. (I have seen a bump of anywhere from 0.016 to 0.020.)
 
Similar experience here. And the same with last year's LR from WE. There's a TON of goodies in those packs that never has a chance to show up on the hydrometer. There's also a boatload of solids that make their way out of that mesh bag.
 
I got similar results adding an M&M grape pack to a wine kit, about .02 increase. The sugar isnt what matters, its more grape solids to make better flavor.
 
Of course it is the total solids and not only the sugars that contribute to the added extract. I expect the majority by weight of the solids that are extracted from the grape skin pack to be sugars - that's why I was referring to the sugars in my original post.

After 48 hours I read 1.083 and after 36 hours 1.078. So, the "bump" I registered was 0.012 (1.087 - 1.075, from 0 to 24 hours). However, this is just an indication, and an underestimate, of the extract contribution from the grape pack. As fermentation is taking place at the same time, the SG is reduced because of the fermentation, and the real extract contribution is not easily measured this way.

The point is that I think the grape pack contains a certain amount of soluble solids, which should be known to the kit manufacturers, and which will contribute a certain amount to the "real extract" of the kit (this is brewers' terminology, but I trust winemakers could understand it). If one wants to calculate the ABV of the wine from the difference between the original gravity and final gravity, there should be a correction to the original gravity caused by the grape pack. It can't be measured easily by the winemaker, as fermentation is lowering the SG during the time the solids are dissolved.

Kit manufacturers should know about this. So why shouldn't we?
 
If you want to know more exactly, I would advise you to just delay pitching the yeast for a day or two. Mix everything up, but don't add the yeast; this would allow most of the sugars to dissolve.

For a rough estimate, I would just add 0.020 to your SG.
 
I waited almost 24 hours to pitch the yeast. Still didn't get much of a bump. The best I can go on is to trust WineXpert, who states this is a 14% ABV wine. I believe it will be at least that.
 
Manufacturer lists finished 14% ABV. if you follow their directions, so it sounds like you could figure roughly 1.105 sg to make that 14%. Ball park 0.03 additional sugar from your grape pack by subtracting the difference.
If I'm anywhere close on my math that is.....
Mike
 
Using fermcalc and putting 1.105 as the starting gravity and .990 as the ending gets anywhere from 15.3 to 15.8% abv depending on the method used. I'd guess that 1.095 is closer to the starting gravity, with some more sugars coming out as the ferment progresses.

With the new kit I'm doing the grape skin bag did go down in volume pretty quickly, but even now when I squeeze it there is a viscosity running between my fingers that is heavier than the rest of the must. Might just be solids (yummy).
 
1.100 to 0.995 and 1.098 to 0.993 both result in 13.8% using standard method or 14.2% using Duncan Acton method. Sounds pretty close to what WE says.
 

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