It is said that harvesting grapes is the most crucial time of the winemaking process, as well as the busiest!!! Grapes have to be harvested at exactly the right time, depending on the varietal (think sugar, acid and tannin levels) and the weather during that particular growing season (think too much rain, frost, to little rain) Another consideration when harvesting is whether to hand pick grapes or utilize mechanical harvesting. The usual picking of the grapes is between August and November above the equator and between February and April below the equator.
The precursor to this most important time in the winemaking process is veraison. Veraison [vay-ray-ZON] according to Ken's Wine Guide, is defined as the point in the growing season when ripening grapes begin to soften and change color from green to either red or yellow, depending on the variety. In the northern hemisphere, veraison typically occurs anywhere from late June to mid August, depending on the climate. (http://www.kenswineguide.com/wine.php?word=86) This process does not necessarily happen at the same time throughout a vineyard, or, for that matter, even for all grapes on a vine or within an individual bunch. Grapes exposed to more sun and warmth can begin to change before the grapes in shadier, cooler areas.
Wikipedia.org
Interestingly, and contrary to what common sense might indicate, if during veraison, the crop appears too large, the decision may be made to thin the yield. The reason for this reduction of grapes is to speed the ripening process by removing unripened grapes, so as to allow the vine to devote its resources to the remaining grapes. A vineyard may also decide to thin the leaves, so as to increase sun exposure, as well as aiding air flow.
As we said, the varietal is an important point to consider when deciding the proper time to harvest. For example, sparkling wines are typically highly acidic and, thus, the grapes are harvested early while late harvest ice wines are at the other end of this spectrum. According to Wine.About.Com, sparkling wine grapes are harvested first, then Chardonnay and Pinot Noir (to allow for decreased sugar levels or brix), then white wine grapes, red wines come next, then ice wines that have highly concentrate sugar for dessert wines.
So, how will the grapes be removed from the vines? There are two traditional methods, by hand or by machine, or a combination of the two. Obviously, harvesting by hands allows for the most precise selection of the very best grapes. However, for larger vineyards with an enormous crop, it may just not be possible. Also obvious, is the fact that mechanical harvesting is a more cost effective and efficient method of harvesting. Ultimately, the winemaker's style will likely be the deciding factor. High quality, smaller production boutique wines are typically hand harvested. With harvesting comes sorting the grapes, which is an important task that removes lower quality grapes from the bunches. This has typically been done by hand, however, WineSpectator Magazine reports, that some of the top Bordeaux Estates have optical laser sorters! As the grapes come down a conveyor, if they are not of the exact specifications desired, a puff of air from a cannon blows them off the conveyor. (http://www.winespectator.com/webfeature/show/id/45607) Amazing!
Shutterstock.com
Finally, the grapes are crushed and destemmed. The grapes are not smashed during this processed, but opened gently so as to allow the juice to flow as quickly as possible. Typically, wineries utilize an automated crusher/destemmer which opens the grapes, but does not crush the stems and seeds. The stems and seeds contain the tannins. Destemmers can remove the stems before or after the grapes are crushed, it just depends on the winemaker's preference and the wine being made. Tannins, add to structure and texture, but also contribute to the sense of astringency or bitterness in wines. If the winemaker prefers a less tannic wine, the stems are removed sooner in the process. For white grapes, they may go first to a press which separates the juice from the skins to avoid a contribution of color or tannins, or they may go through a crusher/destemmer.
Thevintnervault.com
This is an exciting and exhausting time for wineries. A lot of work and manpower goes into this process and it is extremely important that things go well. Harvest season typically ends with a large party to celebrate this most wonderful culmination of hard work!
Stay tuned for Part III when we discuss the next step in winemaking, fermentation!
Cheers!
Mary Jo
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