Towards the definition of optimal grape harvest time in Grenache grapevines: Nitrogenous maturity

Must nitrogen composition plays a key role on wine quality, affecting the development of alcoholic fermentation and the formation of volatile compounds. In order to provide additional information about the optimal time of harvest, we studied grape amino acid evolution pattern in relation to the accumulation of soluble solids along ripening. Additionally, we evaluate the amino acid profile of Grenache (Vitis vinifera L.) grapevines. The results showed that the degree of berry maturity strongly influence the evolution patterns of all amino acids. Grenache behaved as an arginine accumulator variety. This amino acid was found to model the total amino acid concentration in Grenache musts. Generally, soluble solids maturity coincided with the nitrogen maturity at 25 ºBrix. Therefore, in Grenache grapevines, when amino acid composition is aimed to be maximized, the optimal grape harvest time, in terms of nitrogenous maturity, matches the timing at which berries reach their sugar maturity at 25 ºBrix.