DUGi

Estudi dels processos de conservacio i tractament dels vins negres al Celler la Vinyeta

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The oxidation during the vinification is an important problem for the production of wine because it affects to the organoleptic propertys of wine, it changes the flavour and the colour. A research study is made from La Vinyeta winery about its wine-making procedures strating from the barrel to the bottle following the steps of transfer, clarification, estabilization (with CMC or in cold temperature) and filtration with the intention de find possible mistakes that causes an important oxidation in wine. The selected sample is the wine called Llavors, a red aged wine. To be able to study the oxidation on every step of the process, different experiments are performed: – The dissolved oxygen is analyzed because of its capacity to oxidize the wine if it isn’t controlled. The analysis is performed with two different sounding lines. – The amount of free SO2 is analyzed because it is the main character to protect the wine from oxidation thanks to its antioxidant properties. The analysis is perfomed with an automatic titrator. – The wine browning is analyzed to control if the oxidation is enough to cause changes in the colour. The analysis is performed with an spectrophotometer UV-VIS. – Volatil esters that can be used as reference of oxidation are analyzed using a gas cromatography connected to a mass spectrometer with an ion trap and using head space solid phase microextraction as an extraction technique. Except the estabilitzation procedure, the wine-making procedures have proved its fiability. This procedures aren’t affected by a huge oxidation. The dissolved oxygen levels remain constant throught the process as the levels of free SO2 do, that proves a good protection for the wine. The suffering oxidation isn’t enough to change the coulour of the wine. Volatil esters that decrease their own concentration when the oxidation is growing up are determined like the hexanoic acid ethyl ester or the isoamyl acetate. In the end, this study has been compared to other similar studies watching differences on the results due to the different variety of the grapes and in the followed procedure