The timing of the harvest is determined once veraison occurs (the transition between grape growth and the beginning of the ripening process, which involves a change in the colour of the berry). Regular checks are carried out to monitor the evolution of the different parameters involved in quality, which will determine the optimal time for harvesting.
To do this, 100 berries are collected at random and representative of the entire plot, following a zigzag pattern, in sunny and shaded areas and from different parts of each bunch. The analyses include measuring the probable alcohol content (ºBrix, with a refractometer), pH, malic acid, tartaric acid, total acidity, total polyphenols and the health status of the grapes (assessed using gluconic acid) with a Biosystems SPICA oenological analyser.
When the grapes reach an optimal balance between sugar, acidity and polyphenol richness (IPT), it is considered the right time to set the date for the harvest.
At the vineyard pilot project of the Institute of Vine and Wine Sciences (ICVV), at the time of harvest, all the bunches from each plant selected from the reclaimed water and conventional water treatments will be collected. Subsequently, the production components will be analysed: number of bunches per plant, production weight of 10 plants, weight of 100 berries and number of berries per bunch.
A complete analysis of the parameters that determine the quality of the grapes will be carried out on the must extracted from the samples: pH, malic acid, tartaric acid, total acidity, total polyphenols and volatile compounds responsible for the aroma.
