What is cracking?
One of the first techniques for treating the harvest to emerge in winemaking was thermovinification. Originally, the aim was to limit as far as possible oxidation of red harvests caused by Botrytis laccase. This also enabled improved extraction of colour and optimum winery management.
Thermovinification has greatly expanded over the past ten years, particularly in large structures such as cooperative wineries, and the technique has made considerable progress. It is used for the production of quality wines with a fruity and voluptuous profile.
The standard thermovinification technique consists in heating the pressed, destemmed grapes in a tubular heat exchanger at a temperature of around 65 °C to 75 °C for a short time (30 to 40 minutes).
The grapes are then pressed, and the grape juice is filtered, cooled and fermented.
In order to improve the quality of the wines obtained, alternative techniques were developed, such as applying a period of maceration after the thermovinification operation. This is known as hot pre-fermentation maceration. This operation enriches the must in aromas and tannins, thus achieving more stable colouring matter and a more complex wine. Another important development concerning heat treatment of must is the flash détente method developed by INRA in Montpellier. The technique consists in first heating the destemmed harvest, then rapidly lowering the pressure (process of release (‘détente’ in French), which causes the plant cells in the grapes to burst and the temperature to drop to around 30 °C.
This technique leads to increased extraction of the constituents of grape skin: tannins, anthocyanins and aromas, and hence better stabilisation of the colour and structure of wines.
A variation on flash détente is the thermo détente method, in which the extraction of grape compounds is increased further by applying a pressure of 5 bars followed by release.
To find out more, download the technical booklet.
Martin Vialatte solutions
Complex nutrient, for a perfect control of the end of alcoholic fermentation in case of nitrogen deficiency.
Selected pea proteins for the clarification and treatment of musts against oxidation.
Pea proteins in solution for the clarification of musts and wines.
Fish fining powder for the clarification of difficult wines.