Saturday, October 24, 2015

Steps to Consider After Fermentation is Over

Measuring Residual Sugar
So far, we have managed to conduct a constant temperature (60o Fahrenheit), slow fermentation, resulting in a decrease of 1 oBrix a day. We are approaching the end of the fermentation and we are giving careful consideration on how to proceed. When the fermentation was evolving a lot of carbon dioxide, we felt comfortable in opening the fermentation lock to check on the Brix, but now, with most of the sugars converted to alcohol and the carbon dioxide evolution is on the decline, what do we do?
We want to make wine in the style of Domaine Huet and we found a Domaine Huet Fact Sheet published by Europvin. In that fact sheet is the following information:
  • Sec: 11.5 - 12% alcohol; 3 - 5 g/L residual sugar
  • Demi-Sec: 12 -13% alcohol; 10 - 20 g/L residual sugar
  • Moelleux: 13 - 14 % alcohol; at least 30 g/L, but can be anything up to 200 g/L residual sugar
Vinification of the Chenin Blanc grape is about the proper balance of alcohol, acid and residual sugar. Without some residual sugar, the acids take over, so we do want to have a bit of residual sugar in our wine.
To measure the sugar left in our fermentation, we purchased the Accuvin Residual Sugar Test to get an approximate idea of how much residual sugar we have that is below the level of 1 oBrix since:
1 oBrix = 1% sugar (wt/vol) = 1 gram sugar/100 mL = 10g sugar/1L
The range of the test goes from a low of 100 mg/L to 2000 mg/L and if we want to test for 5-8g/L (5000-8000mg/L), we would have to do some dilutions:
Stay tuned!
References:
1. UC Davis Online Course: Wine Production, VID252, Lesson 3, page 6.
2. Daniel Pambiachi, Measuring Residual Sugar: Techniques, WineMaker, April/May 2002.

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