For many wineries, August, September and October are the busiest time of the year. Why? Well it’s grape harvest season of course! Often, the harvest season is celebrated with festivals and events centered around the harvesting of grapes. It keeps old traditions alive and emphasizes the excited anticipation of next years’ batch of wine! Our Wine Blending Workshop is a perfect way to celebrate harvest season by teaching you all about wine making and blending.
Usually, the grapes are picked from the vines when they are deemed ‘ripe’. The ripeness is essentially determined by multiple factors such as sugar levels, acidity and tannin levels. Depending on the type of wine that will be produced from the grapes, these levels may vary along with the optimal picking time. Before modern technology, winemakers would simply taste the grapes to determine if it had reached the proper mix of sweetness and acidity. However, this technique leaves much room for error since taste is a somewhat individual thing and may vary from person to person.
Nowadays, winemakers use refractometers to measure exact sugar levels and specialized tests to measure acidity levels within the grapes. Only recently have tannins started to play a part in the ripeness (or the picking deadline) of wine grapes. Currently, the only way to measure tannins are by taste which obviously takes skill and experience.
Grapes used for sparkling wines, such as Chardonnay and Pinot Noir are generally the first to be harvested in order to ensure lower sugar levels. Most white wine grapes usually follow. As red wine grapes can take longer to reach full maturation, they are picked after white wine grapes. Finally, Icewine grapes are the last to be picked since the process requires them to dehydrate on the vine, making them extra sweet and almost raisin-like. They are picked after a hard freeze which means they must stay on the vine until the weather drop to below 8C.
The weather is probably one of the most determining factors in the harvesting timetable. Too much heat, rain, hail or frost can all have an impact on damaging the grapes and they also make the vines more prone to diseases. The ideal weather conditions for optimal grape growing starts with a cool winter with good moisture. A dry spring, however, is better than a humid one and a temperate Summer with cool nights is optimal. Winemakers generally prefer a dry harvest period in order to bring the grapes home without problem.
Another important factor to grape picking is getting the grapes from vines to crushed as quickly as possible so that the fruit gently splits to let the juice flow out rather than to smash the juice out. It can sometimes be a challenge to get this process done swiftly without the grapes becoming too warm from being transported from the vineyard to the crusher. Often times, the picking takes place in the very early morning where the weather is generally cooler. This helps keep the grapes’ astringency to a minimum.
Since mechanical technics have entered the market, they have been a bit controversial within the industry. Although certain vineyards prefer to keep traditional hand picking technics, within last 50 years, many have preferred to adopt mechanical harvesting. For various economic, labor and winemaking reasons, some winemakers have been forced to apply these modern technics as a result of a reduction of the work force in the wine industry such as in Australia.
Mechanical vine harvesters 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. The sophistication of these machines never ceases to improve and are now able to differentiate grape clusters from mud, leaves and other particles. However, there are still issues with most mechanical harvesters for the distinguishing of ripe healthy grapes and unripe or rotten ones. Therefore, picked grapes often have to be sorted out manually at the winemaking facilities. Another disadvantage of using a mechanical harvester is the potential damage the grapes’ skin can suffer. Damaging the skin of the grape can cause maceration and an undesirable color to the juice in white or sparkling wines. There is also a risk of oxidation and loss of certain aromatic qualities of the wine.
On the other hand, mechanical harvesting is relatively low cost and is able to pick grapes quickly, which can be a definite advantage in for vineyards located in hot climates. The mechanical option can run 24 hours a day and can pick 80-200 tons of grapes in comparison to the 1-2 tons that an experienced human picker can usually harvest in a days work.
However, some wineries prefer the use of human workers as they can better determine which grapes are ripe enough to pick and they are generally more gentle with handling the grapes. Certain dessert wines require each individual berries to be picked from botrytized bunches; a process that can only be done by hand. Also a factor in using human labor is the land where the grapes are grown. In Mosel, where the terrain is steep, it is almost impossible to use mechanical harvesters. It’s also interesting to note that in many wineries, the majority of the pickers are migrant workers along with students and itinerant workers.
Looking to host an event highlighting the harvest for business or pleasure? Contact us for some great ideas or try the ideas above to see for yourself.
*All images from Siebe Warmoeskerken.
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