Harvesting

harvest photoThis season in wine development consists of harvesting, destemming and crushing.

Harvest

harvest photoThe harvesting of wine grapes is one of the most crucial steps in the process of winemaking. The time of harvest is determined primarily by the ripeness of the grape as measured by sugar, acid and tannin levels with winemakers basing their decision to pick based on the style of wine they wish to produce. Harvesting is not only the next step in wine production, but it is also the busiest time of the year for a winery. August through October mark the prime time for the annual grape harvest for most wineries in California. The grapes are typically left on the vine to increase the sugar content and may be harvested up to a few months after the traditional harvest.

harvest photoThe order of grape harvest, in general, would begin with sparkling wine grapes (Chardonnay and Pinot Noir) to ensure lower sugar levels. Next, most of the white wine grapes make their way to the crush. The red wine grapes are typically next in the harvest line, as they take a bit longer to reach full maturation. Finally, the late harvest wines make their way to the crush after undergoing some serious dehydration on the vine to produce a raisin-like grape with highly concentrated sugars - perfect for dessert wines.

Traditional hand-harvesting and mechanical harvesting are the two routes that a winery can take to get the grapes off the vine and ready for destemming and crushing. The question of using mechanical harvesting versus traditional hand picking is a source of contention in the wine industry.

mechanical harvesterA mechanical vine harvester works by beating the vine with rubber sticks to get the vine to drop its fruit onto a conveyor belt that brings the fruit to a holding bin. As technology improves mechanical harvesters have become more sophisticated in distinguishing grape clusters from mud, leaves and other particles. Despite the improvement many harvesters still have difficulties in distinguishing between ripe, healthy grapes and unripe or rotted bunches which must then be sorted out at the wine making facility. Another disadvantage is the potential of damaging the grape skins which causes maceration and coloring of the juice that is undesirable in the production of white and sparkling wine.

hand harvest photoHand picking of grapes are traditionally picked in 30 pound boxes, and in many cases these boxes are consolidated into 1/2 ton bins or two-ton bins for transport to the winery. Manual harvesting has the advantage of using knowledgeable labor to not only pick the ripe clusters but also to leave behind the clusters that are not ripe or contain bunch rot or other defects. This can be an effective first line of defense to prevent inferior quality fruit from contaminating a lot or tank of wine.

Destemming and Crushing

dumping grapes into crusher When the grapes arrive at the winery from the fields they are dumped into hoppers that feed the grapes into a machine for destemming and crushing. Depending on the winemakers objectives, destemming and crushing can be done separately or they can be done at the same time. Destemming is the process of removing the grapes from the stem which holds them.

crusher feeder photoCrushing is the process of gently squeezing the berries and breaking the skins to start to liberate the contents of the berries. Some small amount of stem particles are usually desired to be kept with the grapes for tannin structure. Most white wines are processed without destemming or crushing and are transferred from picking bins directly to the press. This is to avoid any extraction of tannin from either the skins or grapeseeds, as well as maintaining proper juice flow through a matrix of grape clusters rather than loose berries.

The harvest of the grapes is an amazing thing to watch. The grape's intrinsic values of vine type and care have had to deal with the environment and the timing of the harvest to contribute to this year's harvest. We now move on to the fermenting process.

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(This site was created as the final project in Jeff Diamond's Dreamweaver A class.)

© 2009 Ron Boles (updated 3/2/09)