Monday, August 23, 2010

Target SG 1.090

Lots of fruit are coming into season around here, which means it is time for making fruit wine. Thing is, most fruits do not contain enough sugar to make a wine that is stable. That is to say, the sugar in the fruit becomes alcohol, but not at a high enough quantity to act as a good preserver of the wine. Therefore, more sugar should be added until a hydrometer reading comes out to be SG 1.090. This gives the wine a potential alcohol content of 12%. This process is called chaptalization, and is usually heavily frowned upon with grapes and apples, but necessary for other fruits.

I find chaptalization very frustrating.

First off, one would figure out how much sugar is in the juice that you are working with by taking a hydrometer reading. For example, maybe it reads 1.070. Based on Daniel Pambianchi’s Techniques in Home Winemaking, I was converting the specific gravity to degrees Brix, and having to do all my other calculations in metric. What a headache! However, I have recently found out from Ben Waston’s Cider, Hard and Sweet that it takes about 2.25 grams of sugar per gallon to raise the SG 5 points. So, to raise a 1.070 reading to 1.090, which is a 20 point difference, so 20 divided by 5 is 4, which is then multipled by 2.25, so it would take 9 ounces of sugar times the number of gallons you have.

But wait, it isn’t that simple!

First off, it is difficult to get sugar to dissolve into juice, so it is usually added to boiling water first and dissolved. However, the water can dilute your total sugar! Therefore, the syrup that you create should try to be the highest amount of sugar to the lowest amount of water possible.

Secondly, sugar has a volume, even without being dissolved in water. 1 kg of sugar will have a volume of about 0.7L. Therefore, if you have 1 gallon of juice and wish to add 2 lbs of sugar, those two pounds are 0.9 kg, which would have a volume of .63L, or .16 gallons. Since there are 8 pints in a gallon, one pint is .125 of a gallon, so the 2 lbs of sugar will increase your one gallon by a little over a pint! Either you have to toss some juice, or find a new container to put it in because you now have more than a gallon.

So, when chaptalizing, remember:

  • You want a target of 1.090 SG to have a stable wine.
  • 2.25 grams of sugar per gallon to raise the SG 5 points so long as there is no added water.
  • 1 kg of sugar will have a volume of about 0.7L, without water. Adding 2 lbs of sugar is like adding 1 pint.

Further reading:

The metric version of chaptalization:

  • SG 1.090 is about 21.54⁰ Brix
  • One degree Brix means that for every 100 grams of juice (1 Liter), it has about 1 gram of juice, so the juice is 1% sugar. Of that sugar, only 55% of it will become ethyal alcohol. That is to say that the Brix x 55% = the potential alcohol quantity.
  • 9.2 grams of fermentable sugar per liter will increase the Brix by 1⁰.
  • Remember to convert gallons to liters!
  • Again, monitor for volume issues: 1 kg of sugar has a volume of 0.7L

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