I have been pondering about your question regarding gravity shift when adding sugar (i.e. chaptalization) and after a bit of research I think that your numbers are probably O.K. and not out of whack as I suggested earlier.

Having said that, if you want to know why, the following bit in italics goes into the details. This explanation gets a little heavy but stick with it. Hopefully it doesn’t hurt your head hurt too much.

*Claude Jolicoeur has an interesting take on chaptalization in his book (The New Cider Maker’s Handbook), He includes a table for apple juice at different SG’s showing the mass, total solids, sugar concentration, average potential alcohol etc as well as the potential variation in some of these. The table is a compilation of published data from various sources.*

Jolicoeur points out that we routinely use specific gravity (or density) as a convenient proxy for the amount of fermentable sugar in apple juice. But this isn’t completely accurate as the sugar is responsible for less than100% of the measured SG because there are non-fermentable compounds like tannins, acids, etc which also contribute to the density of the juice. For different apples the sugar content of the juice can vary by as much as 10%.

Of course, as Craft Cidermakers we aren’t easily able to measure the actual sugar content, so as a “rule of thumb” we work with what the average figures might be. For our purposes this is fine.

So, although your juice with a measured SG of 1.046 might have the average sugar content for this SG of just under 100g/L, it could really be anything from 90 to 110 g/L depending on the type and condition of the apples. By adding 2 lbs of sugar to 5 gallons of juice (i.e. around 50g/L) you could therefore end up with between 140 and 160 g/L of fermentable sugar, plus the non-fermentable solids that affect the hydrometer SG.

Just to complicate life, adding the sugar also increases the volume and mass of your cider, so the 5 gallons is now a bit more than 5 gallons and weighs 2 lbs more than it did before. A litre of your juice might now have a mass of around 1100g compared with around 1050g before the sugar was added.

So now for the arithmetic. The percent of fermentable sugar (or Brix) can therefore be somewhere between 140g of sugar/1100g of juice (12.7%) and 160g of sugar/1100g of juice (14.5%). The resulting SG range for these Brix figures from Jolicoeur’s table is 1.051 to 1.059 so your measured 1.054 is more or less right in the middle. Another “rough rule of thumb” is that °Bx=°SG/4, so you don’t really even need the table.

*Time to all calm down and enjoy the resulting 6.9% ABV cider.*

Cheers!