Alcohol and Sugar levels

[Antonio58]

I just finished crushing and destemming my grapes, I am going to press grapes in 4 days. When should I measure for sugar and alcohol levels using my Hydrometer?

 

[NorCal]

Measure immediately to know your starting point. I then check once or twice a day to monitor progress.

 

[Antonio58]

Is there a specific starting number with crushed grapes

 

[NorCal]

It depends on the varietal, but generally I like my whites/rose between 22-24, my reds between 24-26.

Ken

 

[CDrew]

Why do you think you will be ready to press in 4 days? It seems like your fermentation will take longer than that. Unless it's really warm, fermentation is about a 7-10 day process.

You use the hydrometer to know where you started, and when you approach dry. You press when you are dry or nearly dry ie when brix are 0 or below. For instance, I started Primitivo on Saturday, at Brix 23.5. Today after 3 1/2 days I'm at Brix 10.

You can only measure alcohol indirectly, making assumptions about how much of the sugar becomes alcohol. An approximation is Delta brix X 0.55.

So if brix at the start is say 24 and you end at -1, the change(delta) is 25. 25 x 0.55 = 13.75% ABV. I have found it's actually just a bit less than that but close enough.

 

[earlmcnelly]

I then check once or twice a day to monitor progress.

Why do you check once or twice a day to monitor progress.

 

[winemanden]

This may be of interest regarding residual sugar in wine!

 

[sour_grapes]

This may be of interest regarding residual sugar in wine!

I would imagine that they are referring to YOUR kind of gallon?

 

[Ohio Bob]

Why do you check once or twice a day to monitor progress.

Speaking for myself...
When fermenting fruits, I stir twice a day to get oxygen into the must. I have my refractometer handy to get a few droplets from the stirring spoon. A free check to make sure things are kicking off. When the Brix change starts to get smaller I’ll take a true SG reading.

 

[winemanden]

I would imagine that they are referring to YOUR kind of gallon?

Yes, you're right. UK Imperial gallon. 4.5 Litres app!

 

[BigDaveK]

Why do you check once or twice a day to monitor progress.

It's important to know that fermentation is still active. Sometimes they'll stop prematurely, become "stuck", and will need help to continue to completion.

 

[NorCal]

Why do you check once or twice a day to monitor progress.

Probably more than necessary, however, the 10 minutes it takes gives me the information I need to have the confidence that things are tracking as expected.

 

[BarrelMonkey]

Probably more than necessary, however, the 10 minutes it takes gives me the information I need to have the confidence that things are tracking as expected.

...and to take action if things aren't on track. Also I think helpful to have as a reference for future fermentations.

I measure baseline brix and temp in juice before starting, then every day during fermentation. Here is my white pinot noir profile from last year:



Ideally I would prefer to keep white wine ferments a bit cooler - definitely below 70 F. Next time I think I'll try to rig up some sort of ice water jacket system for my kegs/carboys.