Dumb It Down For Me??

[firejohn03]

Alright I need some help. Can someone explain specific gravity and its importance? I am kind of lost. I would like to know the alcohol volume of my wine. Does SG play into this? I think it has something to do with sugar content? When is this measured, or what is being measured? Thanks for any help for a complete novice......

 

[novalou]

Alright I need some help. Can someone explain specific gravity and its importance? I am kind of lost. I would like to know the alcohol volume of my wine. Does SG play into this? I think it has something to do with sugar content? When is this measured, or what is being measured? Thanks for any help for a complete novice......

A hydrometer is used for two purposes. It is first used in juice to determine the sugar content. The sugar content gives you a good idea how much alcohol you'll end up with. For example, if you measure a SG of 1.095, it will be a 12% wine.

The hydrometer is then used to track the progress of fermentation. Once it hits 0.990, or does not change for a few days, fermentation is done.

 

[Deezil]

Specific Gravity is a number-based reading scale for determining how much sugar is dissolved in your must (future wine). As you add more sugar to a liquid, the SG number gets higher... As fermentation proceeds and the yeast convert said-sugar into alcohol and CO2, the number falls back down.

Water has an SG of 1.000
Alcohol is "lighter" than water, which is how we get SG's in the .990-.999 range

Readings are taken prior to fermentation, during fermentation and after fermentation

Prior to fermentation, the SG is measured to know the 'starting point' for how much sugar there was to begin with. Post-fermentation, it's measured again to determine just how dry the wine has become... A mathematical formula can be used to determine the alcohol content of the wine, by using these two numbers.

(StartingSG - FinalSG) / .735 = .#### = ##.## % ABV

That's the one I use most often, although there are varying formulas, they're all basically the same

Readings are taken during fermentation, to gauge the speed of the fermentation and to make sure it hasnt 'stuck' for any reason

 

[firejohn03]

I get it somewhat. So I want a drier wine. Do I work toward a lower SG? Does the lower SG increase or decrease the ABV?

 

[Pumpkinman]

(Taken from Beer-Wine.com)
The specific gravity is the ratio of the density of a liquid to the density of water. Water has a specific gravity of 1.000. In case of wine, as you add sugar (water soluble) the specific gravity increases, for example 1.015. The specific gravity indicates the amount of fermentable sugar or potential alcohol in the must (or wine).

 

[Deezil]

Drier wines end with lower SGs

Sweeter wines are fermented the same as drier wines, only they have potassium sorbate + potassium metabisulfite (k-meta) added to 'stabilize' them.. The sorbate keeps any yeast from budding, to make more yeast, to consume all the sugar. So when the wine ferments dry, you add sorbate + k-meta, then sweeten the wine.. The yeast that were exposed to sorbate may eat some of the sugar before dying off but they wont be able to reproduce the next generation of feasters... But this is all for a sweet wine; just throwing that out there.

Dry wines, you ferment down as any other wine and then 'stabilize' with only k-meta, no sorbate.

To keep wine from spoiling, its generally recommended to start with an SG of atleast 1.080

Just to show ya how this works..

Say I'm starting a new wine, with that SG - 1.080
And it ferments for a week
Then it reads right at 1.000 for 3 days consecutively

1.080 - 1.000 = 0.080
0.080 / .735 = 0.10884
= 10.88 % ABV

The 3-day consecutive part is to determine that the yeast have actually stopped feeding on the sugars; without measuring multiple days in a row for the same SG, it's a "shot in the dark" on whether or not the wine has actually finished fermenting or not

 

[firejohn03]

Deezil the formula is putting a lot of this in perspective for me now... Thanks , from a guy with a whole lot more passion than knowledge. I know future runs of wine are only going to get better.

 

[Loner]

If you have a smart phone there is a free app called Brew Majig that will calculate the abv for you.

 

[firejohn03]

SWEET!! or dry the way I like it lol. I have to check out that app. Thanks.

 

[Turock]

firejohn----what kind of hydrometer do you have? If you have the triple read hydrometer, all you have to is turn it to see what brix reading will give you the potential alcohol, and what the SG reading is in relationship to the other two. It's very simple and is really good for a new winemaker. Who needs an app????

If you start with a high SG, you can see on the triple read hydromter that the potential alcohol will be very high. You don't want that. You should shoot for an alcohol content of between 12-13.5% We shoot for 12.5 Alcohol content helps preserve the wine. But too high, especially on fruit wines, can destroy the flavor. Most people don't like high alcohol wines. You want FLAVOR from the fruit or grape--not so high an alcohol content that THAT is the predominate sensation.