18 October 2018

When is the right time to grape harvest? The “likely alcohol content” indicates it to you

If you want to produce a good wine, it is clear that, it is necessary to start from a good raw material, that is to say, the grape has to be harvested in its optimum state. A very important point in this regard is the Baume degree and likely alcohol content that the grape has to set the date of its harvest, also called vintage (there is a direct relationship between the Baume degree and likely alcohol content). As we have already told you on many occasions talking about grape harvesting, vineyards, grapes,... we are not experts in this matter because we do not cultivate this crop. For this reason, we visited our great friend Oscar Escribano at his farm in El Provencio (Cuenca) to talk about the grape harvest, likely alcohol content, optimum state of the grapes, etc.

In order to know when the winegrower must be harvested, we normally use a field or hand refractometer which helps to know the approximate sugar content of the must of our grapes. Besides, it is important to take representative samples of the vineyard (as you can see in the photos), going through the field and selecting both grapes that are in the sun (perhaps 60% of the sample) and grapes that are not exposed to the sun (40% of the sample). It should also be taken into account that the alcohol content is lower in the morning than in the central hours of the day. Once selected the grapes for the sample, they must be squeezed to the maximum to have a representative must. Then, we should use the refractometer to measure the grade. The refractometer contains inside a prism that allows us to measure the refractive index of the grape must. This is achieved once the light passes through a thin layer of fluid and enters the refractive prism, where through the angle of refraction produced, we can evaluate or identify a sample of liquid. In our case, from the refractive index we can know the sugar concentration (measured in Baume degrees) of our sample. The refractometer has inside a scale converted directly to Baume degrees to avoid the use of conversion tables (you can see photos of the Oscar's hand refractometer). The winegrower who does not have a refractometer can take a sample to the winery where it is analysed for free, as you can see in the photos. In some varieties such as Berdejo, Moscatel, Cabernet, Sauvignon Blanc,... the technicians of the winery are who monitor and set the date of grape harvest.

Oscar takes all his grape production to the Campos Reales winery, located in El Provencio. There, the technicians analyse the grapes before entering the winery (they have 6 downloading points so that they can organise all the entries of different varieties). The machine they use is much more precise than the hand refractometer we have mentioned before. This machine extracts a multitude of parameters during the 7 minutes it takes to analyse the sample. Some of these parameters (as you can see in the photos) are Ph, acidity, potassium, rottenness, probable alcohol content,... Undoubtedly, this is one of the best wineries in Castilla-La Mancha that makes extraordinary wines.

The farmer is paid for his grapes according to the kilograms delivered and the probable alcoholic strength he obtains. In this sense, it depends on the variety delivered to the winery. Here are some examples:
  • Cencibel grape (red): 
    • I Grape Category: 13.6 or more probable alcoholic grades. 
    • II  Grape Category: 12.5 - 13.5 probable alcoholic degrees. The winegrower has a penalty on the price.
    • III  Grape Category: less than 12.5 probable alcoholic grades. The grower has a penalty on the price.  
  • Airen or Macabeo grapes (white variety): The winegrower has no range of likely probable probable alcoholic degree. Normally a probable alcoholic degree is between 12 and 13 (you can see it in the photos).

From here, we invite you to taste the great selection of wines that Campos Reales winery have... surely it is an unforgettable experience.

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