The harvesting period varies between July and October (in the northern hemisphere), and depends on many factors, even if in a generic way it identifies with the period in which the grapes have reached the desired degree of ripeness, that is when in the grape the ratio between the percentage of sugars and that of acids has reached the optimal value for the type of wine to be produced. If this parameter is generically valid for table grapes, in the case of grapes destined for the production of wine it is necessary to consider further parameters to decide when and how to harvest.
The time of harvest may depend on:
climatic conditions: as the latitude increases, the grapes mature later;
METHODS OF HARVEST
There are two methods of harvesting grapes:
Manual: it is used for the production of high quality wines and classic method sparkling wines, as it is necessary to make a selective selection of the bunches; this leads to an inevitable increase in production costs;
Mechanical: there are the facilitating machines, which speed up the manual work, and the grape harvesting machines. For plots of less than 50 HA are generally towed machines coupled to a tractor; for larger vineyards they are self-propelled machines. The grapes are harvested in two ways: vertical shaking in machines of American origin, which require a GDC (Geneva Double Curtain) wire and lateral shaking for the machines.
The product that comes off the plant is harvested before it touches the ground, cleans it of any impurities and put it in a hopper which is then emptied into suitable trailers. The mechanical harvest offers some advantages, among which the economy compared to the manual one. For productions that qualitatively satisfy the winery, a manual elimination of those clusters that present diseases or are not yet ripe is necessary.
A practice used is that of the so-called scalar harvests, which consists in collecting the grapes of
the same vineyard at successive times, depending on the degree of ripeness of the individual bunches.
Another practice used is that of the so-called late harvest, which consists in delaying the harvesting period in order to increase the sugar content of the grapes; this procedure is used for the production of sweet wines.
Regardless of the method used, during the grape harvesting phase some rules must be respected: it is necessary to
avoid collecting the wet grapes (from rain, dew or fog), as the water could influence the quality of the must; the hottest hours of the day should be avoided to prevent the onset of unwanted
fermentations; the bunches will be placed in containers that are not too large, to avoid crushing them; finally the grapes must be transported (conferred) to the premises where
vinification will be carried out as soon as possible, to avoid unwanted fermentation or maceration.