Character given to must and to wines by free acids. It is the important element in the balance of wine, in the right measure it brightens the colour, gives freshness to the flavour and promotes conservation (Cited Veronelli). When we talk about fixed acidity we mean the difference between total acidity and free volatile acidity; what is obtained is expressed in grams of tartaric acid per liter. But when we talk about effective acidity, better known as pH, we mean the concentration of hydrogen ions present in the solution and coming from the dissociation of the acids.
