Grapes, picking

Various grape-picking strategies and techniques are applied in botrytized wine making. Regardless, a prolonged or late harvest is necessary a factor which implies risk of losing the crop to bunch rot, other infections or frost under adverse weather conditions. 

Mechanical harvesting facilitates the realization of the above recommendations. Progress in harvest machine technology has helped to avoid berry alteration and excessive vegetal debris. Thanks to its speed and ease of use, the harvester permits a rapid harvest of grapes at their optimal quality level and at the most favorable moment. Manual grape-picking can be even more selective and qualitative, but its cost is not justifiable in all wineries. 

Vine-growers in certain viticultural regions (Champagne, for example) are required to follow these strict rules. Small perforated containers, preferably plastic, are used for grape-picking to ensnre grape quality from the first step of the harvest. These containers are stacked on an open trailer and gently emptied at the winery. 

Certain fruits, notably grapes and dates, may have some surface contamination or infestation when first picked, and they are fumigated with sulphur dioxide or some other gas. They must, of course, then be thoroughly ventilated before going into storage. 

Exploratory studies indicate that 64 mature Valencia oranges per sample, when picked in a consistent manner with 16 fruits from each of 4 randomized normal trees, suffice to give fair (10%) agreement between replicates such a sample ordinarily weighs from 18 to 24 pounds. Very cursory tests with Thompson seedless grapes demonstrate... 

Temperature. The must may have to be chilled immediately after crushing to remove excess field heat. Grapes should be delivered to the crusher as soon as possible after picking and at as cool a temperature as possible. Early morning picking is almost always best. 

Foreign Matter. Leaves, excess stems, dirt clods, and clusters of unripe second crop grapes cannot be tolerated because they can downgrade wine quality significantly, even in small amounts. Rocks, tramp metal, and lost picking knives can damage equipment. 

However, an examination of published worker reentry cases presents a frustrating problem. A compilation of incidents from 1949 to 1955 described cases of organophosphate intoxication from workers in pears, apples, grapes, citrus, and hops (18). Workers were picking, thinning, cultivating, and irrigating. 

Correspondingly, from picking to vatting, handling of the fruit with the least physical alteration is required for maximal development of CM. For example, the pressure exerting by the grape mass on the fruit at the bottom of the vat increases considerably, when tank height is doubled. This increases the quantity of harvest immersed in the must from 15% to 25%. 

Once picked, the grapes are left to dry indoors under ambient conditions. This continues for as long as is necessary to achieve the sugar concentration that is required for each specific style of Vin Santo (26% minimum, up to 45-48% sugar). The dried grapes are then pressed and... 

The less labor intensive, but still expensive, harvest method involves waiting for as long as possible, and then picking the botrytized and healthy grapes together as whole bunches. This method is used all over the world in the making new-style botrytized wines. 

Two basic types of mechanical harvesters are operating in the vineyards. One type uses a set of fingers to beat the grape directly off the vine onto moving conveyor belts. The other hits the trunk of the vine, shaking the grapes off the vine indirectly. The machines normally pick about one acre per hour. Since North Coast pickers harvest 0.5-2 tons per day, the machine can pick the equivalent of 12 to 15 men in an eight-hour day. 

Grapes are picked at optimum °Brix/acid ratio to ensure that the fruit has the best quality characteristics as to sugar, acid, and, in the case of black grapes, color. The intent is to receive the fruit in the best possible condition. 

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