Physicochemical characterization of 'Pinot Noir' grapevine (Vitis vinifera L.) fruit during its growth and development under high altitude tropical conditions

Although native of temperate climates, grapevines are grown in Colombia in the department of Boyaca, between 2,200 and 2,560 m a.s.l. Under these specific conditions, both the physicochemical behavior of the fruit and its optimum harvest time as measured in growing degree days (GDD) had remained unknown so far. On these grounds, in the municipality of Nobsa (Boyaca, Colombia), grapevines of the variety Pinot Noir were physico-chemically characterized during their growth and development. Since day 21 after anthesis (DAA) until overripening, the physicochemical characteristics of 20 berries from each of three clusters we collected every week were carefully assessed. A total of 826.2 GDD accumulated during fruit growth and development, thus completing 126 DAA. The accumulation of both fresh and dry mass followed double sigmoid curves. During early growth there was a decrease in pH, total soluble solids (TSS) and technological maturity index (TMI=TSS/TTA), coupled to an increase in total titratable acidity (TTA). After this period and until harvest, pH, TSS and TMI increased while TTA declined. Based on fresh mass, SST and TMI it was possible to set optimum harvest time at 800.6 GDD.