The grapes have been cold soaking for 3 days now. During that time I diligently exchanged frozen water bottles into and out of the must to keep it cold and prevent any “bugs” from making themselves at home. It’s time to make any adjustments to the must and begin fermentation!
In anticipation of inoculating the must with yeast today, I let the must warm up overnight. Yeast don’t like cold must! Must should be at least 60°F for yeast to be comfortable and start doing their thing.
The must looks very different now: The juice is a deep, rich purple color and the skins are much softer. The must smells delightful and the juice tastes amazing, so I have to think, “so far so good” with the cold soak!
While the grapes were soaking, I got numbers for sugar and acid levels back from the lab:
- Brix: 26.0 (Measured again today for accuracy)
- TA: 5.25
- pH: 3.49
With a Brix of 26, I see that the must’s sugar level is a little on the high side. The ideal range is somewhere between 22–24.5 brix. So I’ll add half a gallon of water to dilute the sugar to about 24.5.
When I add water, I also dilute the acid level, so I have to add tartaric acid to bring the acid level back up. Because the must’s TA (total acid) was a little on the low side to begin with (ideally it is somewhere between 6.0 and 8.0), I added 57 grams of tartaric acid, which brought the must up to about 7.0.
Adding the tartaric acid also has the effect of bringing the pH down. But I’m not worried about that because the ideal pH range is 3.0−3.5. Since the must was on the high end of that scale, it should fall halfway in the ideal range now.
Finally, I’m going to give my yeast some food so they can multiply and have everything they need to ensure a clean and smooth fermentation. When yeast struggle, they can give off noxious aromas that I don’t really want in my wine. I used about 10g of Fermaid K and will add two more smaller doses to the must as the fermentation goes along.
Yeast time! I broke out a packet of Pasteur Red yeast and mixed it with half-a-cup of warm (about 100°F) water. Half an hour later I thoroughly mixed it into the must and covered it in cling wrap to keep air out while the fermentation gets started.