This is our second year of red wine-making. Last year after primary fermentation was complete (@0 Brix), the wine was put into carboys and there was very aggressive CO2 bubbling coming through the air locks for some weeks. This year we did everything pretty much the same except this year almost no action at all in the air locks from day one onward. SO2, TA and pH all look good and the wine tastes fine at this stage.
Why the difference? What would cause little or no CO2 activity?
If the fermentation was finished, the bubbles could be the CO2 gas (fizz) released by the racking into the secondary vessel.
Last year you probably had a lot of dissolved CO2 left, as did many winemakers in Canada in 2002. This year it all came out during the primary fermentation.
The real rule is to stir the heck out of the wine before you add the fining ingredients. Some years it will take 5 minutes and some years it will take 30 minutes. Blame this one on the weather.
Maybe you should try a clinitest to measure residual sugar too; it could be all fermented out this year (I use < 0.2% as a rule). If your wine is pretty cold the CO2 tends to stay in saturation too. As it warms the CO2 can be expelled by stirring.
0 brix is not necessarily dry, it may have had some residual sugar fermenting out last year. Regards, JoeLet's see this step by step:
The yeasts are always excreting the CO2. It dissolves in the must.
The must/wine does not always release CO2 from solution (as your bubbles). In cold weather, it stays in solution. Under high barometric pressure, ditto.
Last spring I had a very hard time degassing, even with two rackings. The wine never got above 21C. The customers who were brewing with heat at 25C had no trouble at all. This May it was fine at 25C: in fact, I had no trouble in getting a perfectly clear, CO2 free batch.
Final step: The CO2, if left in solution, acts as an elevator for the tiny particles. Hence you get it out of there to help the good sedimentation of clarifying agents like kieselsol or isinglass.
Irene
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