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Harvest Journal: The First Ferments

Editor's note: Our wine writer Sarah Chappell is out in Napa this fall, working through the harvest as a laboratory intern at a winery. She'll share her experiences here so we can follow along. Take it away, Sarah!

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I started babysitting them when there were only sixteen, checking in twice a day to see what they were up to. At first they were kind of boring, just lying around doing nothing. But they are now off and gurgling, full of interesting—and disturbing—smells. It feels nice to have traveled across the country to find a new family already waiting, even if they are only barrels of fermenting grape juice.

Yep, that's right: the children that are occupying most of my working hours are the winery's first fermentations of the harvest: pinot noir. I am not the parent, making decisions and directing their future, but I do keep an eye on them to make sure they aren't misbehaving.

This small lot of pinot noir is destined to becoming sparkling wine. Different grape varieties get ripe at different times, and sparkling wine requires less-ripe grapes.

An easy approximation for when grapes will be ready is to think about the finished wine: crisp and fresh sauvignon blanc is usually ready before the richer and fuller chardonnay which requires more hang time (yes, this is a technical term, and does not refer to surfing grapes) on the vine to achieve ripeness. Lighter red grapes like pinot noir ripen before darker, full-bodied reds like cabernet sauvignon. This is not perfect, but gives a good general idea. Sparkling wines require less ripeness, leading to an early pick for the aforementioned pinot noir.

Those grapes arrived the day before I started my job, and were already pressed and lying quietly in used oak barrels when I arrived. The pinot was fermenting using native yeast, which is the yeast population that already exists in the winery or on the grapes themselves. Native fermentations can be a bit unpredictable and the transition from juice to wine can take a while.

While the juice is growing up into my favorite adult beverage, I check in twice a day to measure the sugar content. During fermentation, yeasts convert sugar into alcohol, making the amount of sugar remaining in the juice a good indication of progress. We measure sugar in degrees Brix, one of which equals one gram of sucrose per 100 grams of solution. Brix can be measured in a couple of different ways, but in the cellar we use a hydrometer. This nifty tool looks like a pear-bottomed thermometer and floats in a liquid sample, and the marking on the hydrometer at the surface of the juice tells us about the relative density, which allows us to calculate sugar levels. Fermentation has to be closely monitored to make sure that it is actually happening and that, once finished, the wine can be moved on to the next aspect of its life.

The pinot lots started slow, taking a couple of days to get the degrees Brix moving down. Soon, though, they started to give off a strong fruit-punch scent. These scents are esters, and are telltale signs that saccharomyces cerevisiae yeast (the real winemaker) has kicked into gear. This was quickly followed by eggy aromas that made it rather unpleasant to check the progress. But the stink passed, and the two most ambitious groups have pushed ahead to become wine. It was a surprisingly satisfying moment, after days of seeing the hydrometer faithfully bob back up above the surface of the juice to share the sugar level, to have it sink to the bottom. That failure to rise indicated that the sugars had been converted to alcohol, and that fermentation was complete(!) The yeasties had given up and gone home. (Or died, really. They die drunk. Not too bad, as ends go.)

Phew. I didn't kill the sparkling pinot noir.

More Harvest Journal:

Arriving in Napa »

About the Author: Sarah Chappell is a winemonger and writer living in Brooklyn Napa. She holds the Advanced Certificate with Distinction from the Wine and Spirit Education Trust and has contributed to Foodista, Palate Press and WineChap. Follow her on Twitter @chapsholic.

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