17 brix in the must. Should I add sugar?

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Aug 18, 2023
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First time winemaker here with an unknown variety of red wine grapes from my backyard.

I measured the brix of my grapes at 22 using a refractometer, and the birds were starting to eat them, so I harvested them. Unfortunately, after I crushed them, the 4 gallon must had a brix of 17. I must have not had a diverse enough sample, when I measured the 22. Does that sound right, or is there some other reason why the brix of my must is lower than the grapes?

How can I salvage the situation? Will it even make wine at 17 brix?

Some ideas I had:
Should I add sugar? Would that taste horrible?
Should I reduce store-bought grape juice and add that?
Should I wait until primary fermentation ends, and then add everclear? My thinking here is that the alcohol concentration won't be high enough otherwise, for it to be shelf stable.

Thanks. Any help is appreciated.


wine dabbler
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Nov 5, 2006
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Raleigh, NC, USA
Welcome to WMT!

I agree with Fred, adding sugar to increase brix is perfectly normal. The following post will help you determine how much sugar to add.

Next year you may want to invest is netting to protect the grapes from birds.


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Jan 29, 2014
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* the protective effect of alcohol on a food starts at 5% and basically everything is killed above 18%. A lot of the ABV market breakdown is legal as in there are higher taxes paid on higher alcohol classes. We need to practice cleanliness and minimum oxygen exposure on all products under 18%.
* flavor? Alcohol is sweet but in the scheme of things sucrose gives more impact per gram or percent formulation.
* there are commercial concentrates out which will produce a richer flavor. When I make a syrup at home I have a lot of cooked notes. Try frozen concentrate at the grocery or liter size from Northern Brewer or a local wine supply store. Note, you can change the aromatics by adding concentrate. This may be good if the juice is green/ high acidity, etc. Ripe fruit starts with more so finishes with more.
* back sweetening on the finished wine increases fruity notes. Red wines usually build in tannin notes. While here, apples have a more bitter tannin (hard tannin) which turns to an astringent tannin (soft tannin) as the fruit matures

welcome to WMT

Cap Puncher

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Feb 6, 2021
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Brewers and Vintners - fruit puree and concentrates up to 52 gallons,…

I would do what @Rice_Guy said with concentrates.
You could try to have some concentrate expedited too if you don’t care about mixing varietal. I’ve used them to boost low Brix before but they do add some acid.

I did a Petite Sirah last year from frozen must that came in at 19 Brix. I added the coloma Zinfandel concentrate up to 23 Brix and it came out very nice.

Sugar works though too.
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