A tentative model to describe the evolution of phenolic compounds during the maceration of Sangiovese and Merlot grapes

The maceration of solid parts (dregs) of grapes represents a fundamental step of wine-making not only for the production of high quality red wines but often also of structured white wines characterized by a high content of aromatic compounds. A mathematical model able to describe the time evolution of phenolic fractions during grapes maceration is reported and discussed. While the accumulation of total phenols and catechins in the must/wine during grape maceration can be described by the mass transfer equation introduced by Fick to evaluate the diffusion occurring between two heterogeneous phases, a more complex mathematical approach is introduced to describe the time evolution of anthocyanins. The extraction rate of different phenolic compounds, does not seem to vary significantly with the kind of fermentor or the wine-making technology used, but both the yield and the chemical composition of the extracts appears to be significantly affected by extraction time.