As I mentioned before, I got a half ton of nice pinot noir grapes two days ago, on Saturday. I destemmed and lightly crushed them at a local facility, adding a moderate dose of sulfur dioxide (SO2) to protect the juice during a few days of "cold soak" before starting fermentation.
I brought the crushed grapes, or must, home Saturday evening in three Rubbermaid Brute bins that are now in my garage. The fruit was cold, but Sunday morning I went to the grocery store and bought several pounds of dry ice at the fish counter to add to the bins to keep things chilled. I'm also keeping the garage door open before I go to bed to let the cool night air in.
Cold soaking is the process of macerating the newly crushed grapes to gently allow the color, flavors, and aromas locked in the red grape skins to soak into the wine. Think of it as you would marinating a steak. Each day the juice gets darker and more vibrant red / purple. After maybe four or five days, I'll warm the must to encourage fermenation to begin naturally.
What I'm looking for now are sweet fruit smells, rather than nail polish or vinegar smells that can reduce wine quality. That's VA, which I wrote about last time. I gently stir the bins once a day during the cold soak, and if I smell anything bad, I might spritz the surface of the must with SO2. Anything bad that persists and I'll kick off fermentation right then, as the early signs of VA are often due to cold tolerate yeast and bacteria that quickly get taken over by a vigorous fermentation. The volatile smells even get metabolized, or at least have a chance to blow off as the fermentation produces so much CO2.
Temperatures in the bins are all 49F, actually a little high. I think I'd rather see something closer to 40F to reduce any chance of VA issues right now. In the 50-65F range, bad things can grow quickly so to "kick off" fermentation, I'll look to warm the must to 65F where good yeasts can quickly grow and dominate things.
In order to do the natural fermentation, I think I'll begin to make a starter tomorrow night, much as you would with naturally fermentated bread dough. I'll take a small amount of must in a pail and bring it inside the house to allow it to get going. Once it's going nicely, I'll use it to innoculate the bins to jump start them into fermenation. It's also a nice chance to see if I might have issues with the natural yeast on these grapes, as I haven't worked with this site before (though I know at least one winery that's made wine naturally from here for years, and done very well).
Finally, the numbers. My simple hydrometer reading shows 23 brix, or 23% sugar, in the must. That's just about ideal for elegant pinot noir, provided the flavors are ripe, and they are. That will translate into an alcohol level in the low to mid 13% range, depending on the conversion of sugar into alcohol during fermentation. Someone else with some of these grapes did more specific analysis on this block of the vineyard. The results showed 23.1 brix and 3.27ph, the latter also about perfect for my goal of acid strength being around 3.3, again assuming the good flavors are there.
All told, I'm still really excited about my wine for this year. I'll write more as I finish the cold soak, go through fermenation, and eventually press the wine. If things go well, that might happen on Election Day, which is already something I'm anticipating highly.