Ten Things You Didn't Know About Harvest

Posted: August 29, 2002

1. Sometimes, winemakers look for a little help from above.

No, we don't mean the sun. Throughout much of Europe, the church still plays a central role in harvest tradition. A symbolic bunch of grapes is blessed before the harvest and a thanksgiving service is held at the conclusion of harvest. Senior editor James Suckling attended a harvest blessing in Tuscany in which the following benediction was read:

"God watereth the hills from above: the earth is filled with the fruit of thy works. He bringeth forth grass for the cattle, and green herb for the service of man: that he may bring food out of the earth; and wine that maketh glad the heart of man." -- Psalms 104:13-15.

Some New World winemakers follow similar traditions, holding pre- and post-harvest services or celebrations.

2. Determining a grape's ripeness isn't just a matter of taste.

How do winemakers know when the grapes are ripe? They walk through the vineyards and taste the grapes. When the grapes are ripe, they taste ripe. The structural elements of the wine -- sugar, acid and tannin -- are in balance. This means that the tannins are no longer green or tough, the sugars have climbed, and the acidity has not fallen. Pick your grapes before the sugars have climbed, and the wine will end up lean and overly acidic. Wait too long, and the acids will have plummeted, and you'll end up with a flabby wine without the structure to balance the fruit.

Growers can figure out roughly when to expect to harvest by looking at their records. Each grape variety will ripen at its own pace, depending on the weather, and different vineyards ripen at different times. If one variety grown at a certain site typically takes 110 days to ripen, for example, then the grower can count the days from the time of flowering.

Though it's not very romantic, some science goes into analyzing the grapes and figuring out when the time is right to pick. While part of this work can be done in the vineyard, some wineries also employ labs and men in white coats to determine when to give pickers the green light.

Brix -- a measurement of dissolved substances, mostly sugar, in the grape juice -- is one of the terms you may hear in this context. Most table-wine grapes are harvested at a rating from 21 to 25 degrees Brix. But even grapes that have reached the grower's desired sugar level may not be fully ripe in terms of tannins and flavors, requiring that they hang longer on the vine to develop more maturity.

3. A rose is a rose is ... an alarm system.

Grapevines are susceptible to a surprisingly large number of blights, molds and pests -- all of which represent dangers to both the vines themselves and their grapes. Winemakers need all the help they can get in fending off these attacks and getting the grapes to perfect ripeness for harvest. One of these tricks involves planting rose bushes at the end of a row of vines.

Rose bushes are even more susceptible than grapevines to a particular threat called powdery mildew. As a result, when planted at the end of a row, the roses function much like the smoke alarm in your house. If any of the roses start to die, the winemakers get advance warning that the grapes in that area may soon come under attack.

Of course, the added beauty that roses provide is no small bonus for both the winemakers and those who visit their vineyards.

4. Grape rot might be a good thing.

They might not be pretty to look at, but grapes that have been affected by a particular type of fungus (Botrytis cinerea, otherwise known as "noble rot") produce some of the world's most profound sweet wines, including Sauternes and German beerenauslese and trockenbeerenauslese.

Given a period of humid weather once the grapes are ripe, this beneficial gray mold can attack clusters of grapes, piercing the grape skins so the grapes lose moisture and become as concentrated as can be. Botrytized wines are very sweet and have a complex, honeyed character -- not at all the same result you would get if you made wine from grapes infected with other molds.

However, waiting around for botrytis is an exercise fraught with patience and peril, and the necessary conditions don't always arise. When they do, the harvest goes late into the year, often stretching into December.

5. There's a lot more to picking the grapes than simply getting them off the vine.

Grapes can be picked by hand or machine, and a winemaker must evaluate his goals and needs to determine which is best.

While using machines to harvest is quicker and less expensive (which is good for getting grapes in at ideal ripeness or before bad weather), it can be rough on the grapes. And mechanical harvesters aren't as selective as humans, so they sometimes take in unripe or moldy grapes, as well as leaves or other debris that can add an unpleasant taste to the wines if the grapes are not sorted before crushing.

When grapes are harvested by hand, they are cut off the vine in individual bunches with hooked-tip knives and gently placed into a container that can hold 10 to 20 pounds of fruit. The picker looks for the ripest bunches, leaving any that need more time to mature and eliminating those that are flawed. An experienced picker can harvest up to 2 tons of fruit a day if the crop is heavy and the fruit is at a convenient height. (Vines in some regions, such as Bordeaux or Burgundy, are traditionally close to the ground, making the task of picking them wearisome on the back.)

For certain sweet wines, such as Sauternes or other botrytized late-harvest wines, grapes are picked individually off the bunches, and pickers may make many passes through a vineyard looking for grapes sufficiently shriveled and concentrated by the botrytis. This practice, needless to say, is far more labor-intensive and raises the cost of harvesting.

6. For winemakers, crush time is crunch time.

"Crush" is the time during harvest season when grapes are picked and crushed, and a winery's activity is at its peak. "Crushing" is the winemaking step in which harvested grapes are quickly broken open so yeasts can get into the grapes and begin fermenting the sweet juice. The grapes are often crushed as soon as possible after picking, so that there is little chance for rot or unwanted bacteria to set in.

Some crushers contain two spinning rollers, set close together so that they gently break open the skins as the grapes pass through them. The trick is to not smash the grape seeds, which would add bitter flavors to the wine. Crushing is often done in conjunction with de-stemming in a machine called a "crusher-stemmer." Like the seeds, the grape stems can contain tannins, so if the winemaker feels these tannins might be too much for the wine, the stems are separated from the grapes.

7. Almost all grape juice is "white."

Doesn't red wine come from red grapes and white wine from white grapes? Actually, it's not quite that simple. After all, Merlot and Zinfandel are "red" grapes, but you can find white Merlot and white Zinfandel -- which are actually pink wines -- on store shelves. And two of the three grapes in the traditional Champagne blend -- Pinot Noir and Pinot Meunier -- are reds.

When grapes are first crushed, their juice is "white," or colorless (with the exception of a few varieties that have reddish pulp). Red wines get their color from the skins during fermentation. Like a teabag in a mug of hot water, the skins soaking in the fermenting juice color the liquid. If the winemaker is making a rosé, the juice may be kept in contact with the skins just long enough to give it a pinkish hue.

8. We've come a long way from naked Frenchmen stomping grapes.

Wine production has become increasingly mechanized. While some harvest workers still roll up their cuffs and jump in the tank for certain tasks, very few wineries de-stem and crush manually, and most machine-press their grapes.

Vintner Adam Lee of Siduri Cellars says, "We de-stem using a machine and press using a machine -- but all punch-downs are manual, and we certainly have jumped in a couple of vats." The punch-down involves submerging the "cap" -- the layer of grape skins that forms on top of the vat as the wine ferments -- to extract more color, tannin and aroma. This can be done manually, using poles to break up the cap, but technological innovations -- such as using rotary devices or pumping wine from the bottom of a vat to the top -- have made such work much easier.

A stalwart few, such as some Port producers, still do things the old-fashioned way and stomp the grapes with their feet, believing that this is gentler on the grapes and prevents the bitter seeds from being crushed.

9. Without sulfites, you might end up with a bottle of balsamic.

Sulfites get a bad rap in the wine world, serving as the leading scapegoat for the mysterious "red wine headache" and alarming people with those enigmatic "Contains Sulfites" warning labels. But sulfur dioxide plays an important part in the winemaking process.

Sulfur dioxide occurs naturally in small quantities during fermentation, but most wineries also add small amounts of sulfites during the winemaking process to prevent spoilage and re-fermentation. Without them, many wines will oxidize very rapidly. (Sulfites are similarly added as a preservative to many other products, such as dried fruit.) And certain bacteria on grapes produce acetic acid, which can lead to anything from "off" bottles to full-out vinegar.

The U.S. government requires those "Contains Sulfites" labels on any wine that contains more than 10 parts per million in order to protect severe asthmatics, who may have adverse reactions. Most wines contain about 150 parts per million, and the legal limit is 350 parts per million. In general, white dessert wines need the most protection and therefore have the most sulfites, followed by off-dry whites and blush wines. Dry white wines have less, and dry red wines have the least.

10. There are more than two and a half pounds of grapes in an average bottle of wine.

How many grapes go into a bottle of wine? A heck of a lot more than you might think at first blush. Keeping in mind that these are ballpark figures (the actual results depend on the size of the grapes and how firmly the winery presses), let's run some numbers.

A winery might produce about 60 cases, or 720 bottles, per ton of grapes. About four and a half grape clusters weigh one pound, so that works out to 9,000 clusters for every 720 bottles, or about 12 clusters per bottle. Guesstimating that there are about 40 grapes per cluster means that there are about 500 grapes per bottle. Whew! All that math can make you thirsty.

Got more questions? Check out our Harvest Glossary, and see Dan Sogg's "Inside Wine" articles on adding tannins and canopy management.