These instructions are for a volume 19 Litres of base wine, but formulas at the end of this article will provide successful results with other volumes.
Advance preparation before starting yeast culture
Requirements for the base wine: The wine should fermented dry, have sulphite levels below 20 ppm, it should be heat and cold stable and to assure the best results it is recommended it be filtered.
Preparation of culture solutions
Step 1.Pull off wine for starter.
From 19L draw off 475 mL of base wine (ie 2.5% of total wine volume) into an appropriate container. The base wine should have an alcohol content of about 11% based on Brix of 18 in grapes when picked.
Step 2. Make a water/sugar syrup
Put distilled water into another container equal to the volume of starter wine (ie. 475 mL). Dissolve enough sugar in the water to get to 10 Brix; in other words 100 g /L. (.475L x100 g equals 47.5 g ) of sugar. Note: if possible heat the syrup close to a boil and allow to cool overnight.
Step 3. Make a 50/50 solution for step 4 below
Take one half of the wine ( 237.5 ML) and combine it with one half of the syrup (that is 237.5 mL). This will result in 475 mL of a 50-50 solution and 11% alcohol in the base wine now will be reduced to 5.5% alcohol and used in step 4 below.
Reserve: There will still be 237 mL of wine and 237.5 mL of the water/sugar syrup left which will be used in step 5
Starting the yeast culture
Step 4. Prepare the yeast
Rehydrate 5 g of EC 1118 yeast using 6 g of GoFerm. Use standard yeast rehydration procedures using GoFerm.
When the yeast is sufficiently hydrated start adding some of the 50/50 solution from step 3.
When the fermentation is underway add the yeast to the remaining 50/50 solution prepared in step 3.
The yeast will start fermenting and consuming the sugars; not much will happen during the first 12 hours, but in approximately 24 hours the Brix should be down to 2.5. Stir a couple times during fermentation. Note: ambient temperature is important so keep the temperature at 72 or higher during the fermentation. Optimally monitor the Brix, adding sugar, during the process so that it doesn’t drop below 2.5.
After 24 hrs.
Step 5. The second phase of growth; completing the Liqueur d’tirage
This step will raise the Brix of the yeast starter from 2.5 to 5.
Take the remaining reserve of 237.5 mL of the wine from step 3 and combine it with the remaining 237.5 mL of syrup from step 2 to make 475 mL at 5 Brix.
As the yeast culture is now reduced to 2.5 Brix add enough sugar to it to increase it back to 5 before combining it with the reserve above. This amount should be about 12g. Stir to dissolve.
Combine the culture with the reserve. The volume will now be 950 mL
Add yeast nutrient DAP to the starter at the rate of 0.1 g/L.
Allow it to ferment back down to 2.5° for about another 24 hrs. Monitor Brix as in step 4and adjust as necessary.
After 48 hrs
Step 6. Prepare the base wine (cuvée) for the liqueur d’tirage.
Sweeten the base wine by 24 g/L of sugar to it. (24g x 19L =456g) Dissolve the sugar in the wine not in water
Add 0.1g/L or 1.90 g/19L of DAP to the cuvée.
You may also wish to add an agent to assist with riddling as an option.
Add the yeast starter (liqueur d’tirage) to the cuvée and stir thoroughly. Bottle immediately.
Bottling
Stir the cuvée continuously when bottling to make sure that the yeast and riddling agents are uniformly distributed during bottling.
Formulas for volumes other than 19L
Calculated volumes are dependent on drawing 2.5% of the base wine. Match it with an equal volume of distilled water. Both the base wine and water/sugar are divided equally and recombined as in steps 1 through 3 above.
In step 5 to calculate the amount of sugar to add to the fermenting culture after 24 hrs. to bring it to 5 Brix from 2.5 Brix the formula simply is: (V in L to be adjusted X change in degree of Brix required X 10g sugar for each degree).
Therefore for the above19L base wine volume: Sugar addition in grams is 0.475L X 2.5 X 10 = 11.875g or about 12g
Contributed by Mike McInnis