meadmaker1
Member
When adding fruit or juice to mix after pimary fermentation, what is the prosses to adjust sg calc for an accurate end result
hydrometer ?
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Scooter68
Fruit "Wine" Maker
We need to first assume that the batch will ferment dry at an SG of .990
Subtract your current SG from the Initial SG.
Once you have completed the process of adjusting the SG (Assuming increasing it) you can add the difference of Initial SG and the SG at the point where you added more sugar to the new adjust SG and then calculate your ABV.
e.g Initial was 1.080 but you decided to add more sugar for a higher ABV when the SG had dropped to 1.060. The difference is .020 to be added to the new SG once you have increased the SG.
If you increased the SG for 1.060 to 1.075 then add .020 to 1.075 for an SG of 1.095
If the batch ferments dry the final ABV will be 13.79%.
BUT - this will not be 100% accurate because in all likelihood you added some liquid to batch increasing the volume and slightly diminishing the existing ABV. None-the-less unless you added a lot of liquid then the quantity will not have a dramatic impact. In the example an addition of 1 quart would mean that the volume increased by 5% and subtracting 5% from your ABV would mean the ending ABV should be 13.1% a net increase of 1.98% from the original 11.81%
IF you do this addition while early in the primary fermentation process there should not be an issue with stirring up the lees. If the batch is already in the secondary phase or nearly ready to be racked into a secondary fermentation carboy you might want to wait until it's been racked.
Someone else may have worked up a formula to allow for the volume increase - we'll see if anyone chimes in here.
Subtract your current SG from the Initial SG.
Once you have completed the process of adjusting the SG (Assuming increasing it) you can add the difference of Initial SG and the SG at the point where you added more sugar to the new adjust SG and then calculate your ABV.
e.g Initial was 1.080 but you decided to add more sugar for a higher ABV when the SG had dropped to 1.060. The difference is .020 to be added to the new SG once you have increased the SG.
If you increased the SG for 1.060 to 1.075 then add .020 to 1.075 for an SG of 1.095
If the batch ferments dry the final ABV will be 13.79%.
BUT - this will not be 100% accurate because in all likelihood you added some liquid to batch increasing the volume and slightly diminishing the existing ABV. None-the-less unless you added a lot of liquid then the quantity will not have a dramatic impact. In the example an addition of 1 quart would mean that the volume increased by 5% and subtracting 5% from your ABV would mean the ending ABV should be 13.1% a net increase of 1.98% from the original 11.81%
IF you do this addition while early in the primary fermentation process there should not be an issue with stirring up the lees. If the batch is already in the secondary phase or nearly ready to be racked into a secondary fermentation carboy you might want to wait until it's been racked.
Someone else may have worked up a formula to allow for the volume increase - we'll see if anyone chimes in here.
Last edited:
BernardSmith
Senior Member
This is an interesting question. Technically, you simply add the additional volume to the starting volume and the additional quantity of sugar to the starting quantity of sugar and then divide the total amount of sugar by the total volume of liquid. If you then multiply that number by 1.040 you will obtain the total equivalent of the starting specific gravity. If you started with one gallon and you had dissolved one pound of sugar your specific gravity would be 1.040. If you simply added another lb of sugar the gravity would be 1.080. If you added another 1/2 gallon of water the total volume would be 1.5 gallons and the gravity would be .080 divided by 1.5 = 1.053 . To determine the potential ABV you then multiply this quotient by 131 (1.053 *131 (or about 7% ABV)
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meadmaker1
Member
Thank you for replys
As usual a certain amount of theory holds the answer, of course based on science math and practice.
But what ive come to believe is that I would test sg change and add it to change after completion.
But because I am adding fuit and it contains water I may not acualy be increasing sugar due to volume.
And because I started this wine thing because I prefer less dry to sweeter wine, straight juice from the fruit has tested lower than original but super Close so I don't believe it will vary much any way..
As usual a certain amount of theory holds the answer, of course based on science math and practice.
But what ive come to believe is that I would test sg change and add it to change after completion.
But because I am adding fuit and it contains water I may not acualy be increasing sugar due to volume.
And because I started this wine thing because I prefer less dry to sweeter wine, straight juice from the fruit has tested lower than original but super Close so I don't believe it will vary much any way..
meadmaker1
Member
New question
Since I expect residual sugar can I expect my alcohol lvl to max out at the threashold of the yeast I choose.
Since I expect residual sugar can I expect my alcohol lvl to max out at the threashold of the yeast I choose.
It would be easiest to do a weighted average. This takes in to account the added volume of your juice and requires no assumptions of when you're batch will go full dry.
So take you initial Sg, your Sg going into secondary and determine your current alcohol. Write this number down and call it 1. Subtract your current alcohol from your original potential alcohol, and you have your current theoretical potential. Call this A.
Prepare your addition at secondary and take a Sg reading to determine the potential alcohol of your addition. Call this B
Now multiply A by the size of your original batch in ounces C, and multiply B by the size of your secondary addition in ounces D.
Add AC to BD, and divide by C+D. Call this E.
E is your new potential alcohol moving forward in secondary.
At the end, take a Sg reading and determine your final alcohol potential. Call this F.
E minus F equals your alcohol production in secondary. Call this 2
Your TOTAL final alcohol is 1+2.
(edit)NOTE: this will be as accurate as you can get for a juice addition. for a fruit addition, crush and cold-soak the fruit to get the most accurate sugar reading possible, then treat it like a juice addition. most fruit are more water than solids, so the fruit itself won't skew your numbers too much.
Last edited:
Scooter68
Fruit "Wine" Maker
Actually, No - the tolerance of the yeast is just part of the equation - there are also variety of other factors. You could have a yeast capable of a high ABV stop before that point if something prevents the yeast from converting all the sugars. Yeast is a living part of the wine process and just like people, things can disrupt its life cycle. Nutrients, Temperature, Acid Level are the major elements that could stop the fermentation along with additives that prevent further reproduction of the yeast bacteria.
I had a yeast capable of 18% that stopped completely at 16.67% - Starting SG was sufficient to support an ABV of 18.37%. Despite efforts to get it to complete it never moved. The upside was that the finished out at an AG of 1.005 -sweet enough and with a Strong Black Currant flavor that made it a great dessert wine.
