How to Know When to Harvest?
Harvesting is a very delicate procedure, as is choosing when to harvest. This task is laden with responsibility as choosing the right time can mean the difference between having an excellent wine and one which is just a tad overripe or in the opposite case, too green.
To choose the perfect time, winemakers make use of a refractometer. Refractometers, measure the index of refraction of a solution. In the case of winemaking, it is used to measure how much sugar content ais in the grapes which will then be converted into alcohol once the fermentation process is complete.
A selection of 100 Pinot Noir grapes will serve as a representative sample of the vine.
In order to measure the approximate amount of sugar contained in the grapes of a specific vineyard, a representative sample must be collected. The sample is constituted of 100 grapes from different areas around the plot in order to have the most realistic sample possible.
The grape samples are crushed to reveal their juices
Pouring the grape juice over the refractometer lense
Once the grapes are collected, they're crushed to reveal all their juices. These juices are then poured over a refractometer in order to measure the index of refraction which will detail the amount of sugar contained in the juices.
The refractometer is held up to the sky against the light, to measure the sugar content
After closing the flap, the refractometer is held up against the sunlight to measure the index of refraction. With the help of a chart, this index can then be converted into the future alcohol content after fermentation. This number is crucial to knowing when to bring in the harvest, as the longer the grapes stay on the vine past the optimum alcohol percentage than the more tonnage you loose.
The perfect time will differ depending on the wine region as well as the varietal but in general terms for the northern hemisphere, the harvest takes place from the end of August to the end of September. This year the harvest has started particularly early due to the unusual climatic conditions. The word is still out on whether this year will be a particularly good vintage, more is yet to come...