Measuring the density

In my previous reports I have mentioned that the natural yeasts of the Albariño in our denomination are not vigorous enough on their own to sustain the alcoholic fermentation. For this reason we are obliged to seed the tanks with selected yeasts to help convert the natural grape sugars into wine.

One of the key factors during this process is temperature control – the higher the temperature, the faster, and therefore shorter, the fermentation. Extremes of temperature, either too hot, or too cold can make the fermentation stick, and will ultimately have a detrimental effect on the finished wine. In white wine making temperature is especially critical, and we therefore analyse the grape must at least twice a day to monitor the speed of the reaction.

The method we use is quite simple, measuring the density of the must – in effect looking at the rate at which the sugar is being consumed. Examining the results gives us the information that we need for temperature control – if the sugar is being consumed too quickly we lower the temperature a little.

Depending on the temperature used, fermentation can take anything from one, to three or four weeks.