In the third and final part of Grant’s harvest blog series, we rejoin our grape must, about to undergo the transformation into wine…
Step 3. Fermentation
When the must has been inoculated, fermentation is kick-started to action. The yeast eat the sugar, producing byproducts of alcohol, carbon dioxide, and heat. When a fermentation batch is at its peak, temperatures in the wine can climb above 100 degrees Fahrenheit. While the must is a cookin’, the skins and seeds rise to the top and form a layer called the cap. Two to five times a day, this cap needs to be pushed back down into the liquid. This is known as a punchdown, and promotes uniform extraction of tannin, color, and flavor, as well as prevents the cap from drying out or molding. Punchdowns are also a great form of exercise! I recommend volunteering for punchdown duty at my winery this fall. You can stop by whenever you like :)
Had a few close calls, but I swear I've never fallen in!
Fermentation continues until one of three things happens:
- The wine is fermented dry, meaning all of the sugars have been consumed by the yeast and transformed into alcohol; or
- The yeast is killed by high alcohol levels. This is why you rarely if ever see wines above 15-16% alcohol by volume, the yeast just can’t handle it
- Fermentation is stopped by the winemaker, in order to preserve residual sugar in the wine. If the winemaker wants to leave a bit of sweetness in the wine, this is how it is accomplished
Step 4. Pressing
Once fermentation is complete, the grapes are pressed to remove any extra wine trapped within the skins. Less pressure is often used on more delicate wines such as Pinot Noir, in order to minimize edginess and rough tannins. Higher pressure can be used on bigger wines, such as Cabernet Sauvignon, to extract more tannin and color. After pressing, the wine is pumped from the press to the tank or barrel. In the barrel, the wine will age and go through secondary or malolactic fermentation, where the tart and rough flavor of malic acid is converted to the softer and rounder flavor of lactic acid.
Harvest is different each and every vintage, but is always an exciting time in the winery. Some years, all the grapes ripen at the same time and we work 16 hour shifts for weeks. In other years we’ll have a 3-day rest between crush days and time to barbecue for lunch. It all depends on what Mother Nature chooses to throw at you, one of the many reasons making wine is so much fun and so special.
For all of the wine lovers out there, I highly recommend volunteering at a winery during harvest. Just remember, half of winemaking is washing the equipment afterwards.
Once all of the grapes are harvested, sorted, crushed, fermented, pressed and barreled, “crush” is officially over. Time to relax, plan a surf trip, and have a beer (also known as Step 5).