Agriculture Reference
In-Depth Information
Adjusting Sugar Levels
As I mentioned earlier, in order for a wine to be
self-preserving, it should have at least 9% alcohol. The
following table gives you the potential alcohol based upon
specific gravity, and how much sugar is present in a gallon of
must to give you that much alcohol if it is completely
fermented by the yeast.
Because water may be added to the wine at some
rackings—thereby diluting the alcohol—you should also aim
for a starting specific gravity that exceeds 1.080,
corresponding to 10.6% alcohol. Also, even though a
particular strain of yeast might have a theoretical alcohol
tolerance exceeding 20%, such yeasts will not thrive in musts
containing enough sugar to make that much alcohol. Higher
levels of alcohol like that are achieved by fortification or by
adding small amounts of sterile sugar syrup as existing sugars
in the must are depleted. In order to avoid a fermentation
failing due to excessive sugar levels, you should limit the
initial specific gravity of your musts to no greater than 1.100,
which corresponds to 13.6% alcohol. So, aim for a starting
gravity between 1.080 and 1.100. In practice, I use 1.090 for
almost all of my wines.
Almost all of your musts made from pressed or juiced fruits
will contain insufficient levels of sugar to reach the minimum
necessary alcohol content. Even though I am about to cover
the math in more depth, the following shortcut equation will
work fine:
Ounces of Sugar = (Desired S.G. - Measured S.G) x 360
