Tuesday, October 16th 2018
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Published on February 27, 2014 0

Mechanical Harvesting

Wine, which outlived a history of thousands of years, has witnessed its renaissance in the last 50 years. The influential changes and developments can be observed both in winemaking and in viticulture.

Basically, viticulture is concerned with variety of processes from growing grapes in the soil to taking them to the winery. Vineyard management became much more efficient with the introduction of vineyard mechanization techniques. In virtue of this development which requires much less labour for planting, pruning and harvesting, the regions with labour shortage are no longer desperate in managing the vineyards  

Over the last few years, with the vast improvements harvesting machines have become more sophisticated, more effective and gentler, hence causing less damage. Many wine regions around the world have adapted mechanical harvesting. Mechanical harvesters remove the fruit from the vine by either slapping it using paddles or by shaking the vine. Fruit is caught with horizontal conveyor belt and collected in a supporter vehicle. This innovation requires vineyards to be designed according to the machine type. The machine cannot be used in untrellised bush vines or vines with high pergolas and dense plantings. Steep slopes are also a challenge and “manufacturers recommend that harvester exceed vertical slopes of 35 degrees and a side slope of 20 degrees.”(Bill Pregler. “Making mechanical harvesting work.” Wine business monthly, November 2009)

There must be sufficient row space that allows a harvester to pass and fruit tires must be tight. Use of machines is feasible on large vineyards because machines are expensive to purchase. Mechanical harvesters are also used as a tool for precision viticulture by attaching a GPS device and yield monitor in large vineyards. (Jamie Goode. Wine Science. The Application of Science in Winemaking, Mitchell Beazley: 2005)

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Harvesting is not labour intensive if it is done mechanically. It requires only the labour of a machine driver. While in some countries such as Australia shortage of vineyard labour makes mechanical harvesting indispensable, in other countries high labour costs make it essential. Another advantage of machine harvesting is time saving. One machine can harvest in one hour what it would take at least twenty five grape workers to pick in the same period of time. Speed is very important especially when the fruit is over-ripped or in case of bad weather conditions such as rainy harvest. In these circumstances, mechanically harvested grapes result in better wines since crop can be brought to the winery urgently; otherwise the operation has to spread over several days. With this technology, it is possible to pick grapes at optimum ripping level with the ideal acid and sugar balance. It further allows harvesting to be done at night because mechanical harvesters are equipped with halogen lamps. This is extremely important for hot regions where daytime temperatures are too high. Since nights are cooler in these regions, the oxidation risks and the cost of cooling the juice before fermentation can be minimized. It is a great advantage to harvest at night for regions where the grapes are transported hundreds of miles to the wineries. Harvesting grapes at coolest temperatures retains freshness and fruit flavour. Mechanical harvesting significantly increases wine quality in large vineyards and hot regions by harvesting at night.

During mechanical harvesting, some grapes are harmed since berries are split and juice is released, which in turn give rise to oxidation. However, oxidation can be avoided at this stage by using sulfur dioxide. Another consequence of split berries and released juice is excessive skin contact in white wines. Hence, if the vineyard and the winery are located far away from each other, it is not appropriate to use white grapes that harvest mechanically for quality white wine making. Fruit selection is not possible with mechanical harvesting; ripe and unripe berries can be harvested at the same time especially if the vineyard is mechanically pruned. (James Halliday& Hugh Johnson.  The Art & Science Wine, Mitchell Beazley: 1994)

Since mechanical harvester cannot be selective, this may reduce wine quality if many unevenly riped fruit exist in the vineyard.

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Materials other than grapes have been another challenge for mechanical harvesters. Mechanically harvested grapes could contain some leaves, petioles or snails which may in turn cause some taints and have negative effects on resulted wine. However, recent developments of mechanical harvesters have decreased this problem significantly. For specific wines, such as sparkling wines where a whole bunch is used and for wines made by selective grapes with noble rot, handpicked grapes are preferable to mechanical harvesting.

Nevertheless, many top-quality wine producers still prefer the more gentle process of hand picking rather than mechanical harvesting. Evidently, as I have initially mentioned, the use of mechanical harvesting is a matter of controversy even though sophisticated mechanical harvesters has no negative effects on resulted wine. For example, vast majority of Bordeaux region prefer mechanical harvesting because of its speed, whereas some producers of Bourgogne region argue that the use of mechanical harvesting is the sign of bad reputation for their wines. (Oz Clarke. Bordeaux, Pavillon Books: 2009)


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