Robert – October 14th, 2012
According to my wine book, a single teaspoon of fermenting grape must can contain 400 million active yeast cells. That means we have about 12 trillion yeast cells in our 40 gallons of must. It’s a party over here, you guys, and everyone’s invited!
On Friday evening, we had a lot going on. To you, “have a lot going on” might mean a hot night out on the town. To us, “have a lot going on” means standing around watching our wine ferment. It’s pretty exciting. There are bubbles!
When I signed off on Thursday, the Vidal Blanc juice had just started showing the initial signs of fermentation. The Cabernet Sauvignon and the Cabernet Franc grapes were still in their cold soak. As of Friday evening, here are the major developments:
The fermentation of our white wine is no longer cause for concern. We should have known. Slow and steady wins the race.
Our white is now fermenting quite nicely, as evidenced by the bubbles coming up through the ferm lock, which you can see in the animation I’ve included in this post. Our objective going forward is to keep the temperature very low, so the fermentation continues at a slow and steady pace. When I measured the juice on Friday morning, we were at a yeast-friendly 64 degrees. As long as the juice stays below 70 degrees, we should be in good shape, although the 60 degree range is closer to ideal.
We are storing the carboy containing our white in the coldest part of our house. The room is about 61 degrees right now. This is helping to keep the carboy cool…for the moment. Unfortunately, the temperature in the room alone will not continue to provide us with the control we need. The juice will rise in temperature as the yeast convert sugar into alcohol and carbon dioxide. It literally warms itself up. If we simply left the carboy in the room at 61 degrees, we could reasonably expect it to be above 70 degrees within the next 48 hours. To keep the temperature down where we want it, we plan to move the fermenter to a large turkey roasting pan full of ice water. Added bonus: ready for Thanksgiving!
I also took a Brix reading on Friday morning. We were down to 19 Brix (which means the juice was about 19 percent sugar by weight, as discussed earlier). This was down from 22 Brix, meaning that about 14 percent of the sugar in the juice had now been converted to alcohol or carbon dioxide by the yeast. The Brix will continue to fall until it actually drops a bit below zero (more on how that’s possible coming to a post near you very soon), at which point the fermentation will be complete. All in, the white will ferment for approximately 10 to 14 days.
Our red must was infiltrated by wild yeast, accelerating our fermentation timetable.
On Thursday night, the red must that had been in a cold soak was starting to fizz. This meant that the wild yeast present on the grapes and in the air had started to take hold. Insidious bastards. I imagine the wild yeast wearing tiny bandit masks and brandishing tiny six shooters. Not in my town. It was time for us to start the fermentation on our red, ready or not.
For the red, we’re using Red Star’s Pasteur Red yeast, which is perfect for powerful red grapes like Cabernet Sauvignon and Cabernet Franc. At about 6:00PM on Thursday night, I rehydrated the yeast in six doses (one for each fermenter) for about 30 minutes, then added them to the fermenters along with five grams of yeast nutrient each.
Fermentation temperature is very important for a red wine. While we’re spending lots of time and energy trying to keep the white cool (and its fermentation slow), we want the exact opposite for the red. At the peak of fermentation, our red will ideally reach 90+ degrees.
We have a trick to get the red up to correct temperature after completing the cold soak. The spare room we use to store our red fermenters is equipped with an electric heater, which is perfect for heating up the room to aid fermentation. When I added the yeast on Thursday night, I cranked up the dial. By Friday morning, the red must had already increased to 68 degrees (from 45 degrees at cold soak, to 53 degrees when the yeast was introduced). The red fermenters are going like gangbusters; lots of fizzing, bubbling, and some serious whiffs of carbon dioxide. There ain’t no party like a fermentation party, ’cause a fermentation party don’t stop!*
*Yes it does.