Determining Initial Brix / Specific Gravity
A common question on WineMakingTalk is “What should the initial brix / specific gravity (SG) of a wine be?”
The short, but totally unhelpful answer is, “Whatever you want it to be?” This is a difficult question to answer, because it’s very much situation specific.
Before continuing, please note I’m not a grape or fruit grower, so I have to purchase or forage my winemaking materials. I’ve noticed that grape growers, and the folks they train, tend to think in terms of brix, e.g., percent sugar. Knowing brix is critical to grape growers, as it’s part of how they determine the grapes are ripe.
I think in terms of SG, as it’s what I learned. Also, while knowing the initial brix is valuable, knowing the Original Gravity (OG) is the same thing, and once fermentation begins, the brix is no longer accurate. Fermentation produces alcohol, which is lighter than water and skews the brix reading, so that it’s no longer the percentage of sugar. Sure, there are tables that translate, but when I take an SG reading, I know what I have without translation. For me, it’s easier thinking, even if taking an SG reading is more effort than using a refractometer (which measures brix in juice).
Since I’m not a grape or fruit grower, I generally get what I get. Grapes are different every harvest, and there is variation within a vineyard, so measurements are not 100% accurate until I crush the grapes and stir. If the sugar is low, I’ll chaptalize, while if it’s high I may have to water back with acidulated water (water with calculated amount of tartaric acid added).
Non-grape fruits? All are low in sugar, for winemaking purposes, so all need added sugar.
The question is “how much sugar?”. It depends on the type of grape/fruit, and what style I’m making.
A “big” red is characterized by being full bodied, higher in tannin, and higher in alcohol. The higher ABV (Alcohol By Volume) both balances the heavier body and tannin, and it helps in extracting them from the grapes and oak, to produce the big red. For these I target an OG of 1.095 to 1.105, with 1.100 as the sweet spot.
I’ve made wines with a higher OG, but found them to be unbalanced with an alcohol bite. A lower OG produces a wine that is likely to fall short of the ideal — it can still make a good wine, but it won’t be a big red.
Which red grapes to use for this? Most of the red Vitis Vinifera grapes can be used, e.g., Cabernet Franc, Cabernet Sauvignon, Gamay, Malbec, Merlot, Shiraz / Syrah, and dozens of others. Some of the hybrids can be used, e.g., Chambourcin, Leon Millot, and Marechal Foch.
ANY red grape can be used to produce a lighter red. The real difference is the lighter body, tannin, and ABV. This includes red Vinifera, hybrids, Muscadine (Vitis Rotundifolia), and Concord (Vitis Labrusca).
Why make a lighter red? In many cases the grapes lack the constituents to make a big, heavy red. The grape just isn’t appropriate for that use.
There’s also winemaker’s desire — I make lighter reds are they match with lighter foods, AND I like variety. I love big reds, but don’t want to drink them all the time.
For these, my target brix is 1.085 to 1.095 (20.3 to 22.5 brix), with 1.090 as the sweet spot.
My target range for whites is the same for lighter reds, although I tend to focus more on the varietal. Chardonnay is a heavier white, so I prefer to start with a higher OG, while other whites I prefer at the lower end. Whites do not have the body of even a light red, so it’s easier to off-balance them with too much alcohol.
“Orange” wine is made when a white grape is fermented on the skins. The normal procedure is to crush and press the white grapes, then ferment the juice. Orange wine is made like reds — crush, ferment, then press. The name comes from the color imparted by the skins, and the body tends to be like a lighter red.
Note that I’ve not made orange wine myself, but have helped others do it. I’d treat this like a lighter red, having a slightly higher OG than a white juice.
Fruit / Country Wines
This is the hardest category to give advice on, as fruits vary so much. For the most part, I treat fruit wines like whites / light reds, where the lightest fruit (e.g., Apple) has a lower OG, whereas darker fruit (e.g., Blackberry) has a higher OG. As with lighter reds and whites, the body of the fruit directly affects how high the ABV can be without unbalancing the wine.
I don’t go below 1.080 for any wine, as it produces an ABV below 10%, which negatively impacts shelf life — wine is a lot more stable at 10% and above.
Conversely, I’d consider starting an Elderberry at 1.100, as it has the body to handle it.
Please note the above ranges are approximate — they are my personal guidelines, not hard-n-fast rules. I may have listed slightly different answers in threads on WineMakingTalk, and in a given situation I may go outside the “guidelines”.
Every batch of wine is distinct, and what I do in a given situation will be driven by the materials I have on hand, what I believe I can produce with them, and how experimental I’m feeling.
I have added a SG to Brix conversion table as it may be useful: