Variability in Volatile Composition of Crimson Seedless (Vitis vinifera) in Association with Maturity at Harvest

Abstract

Crimson Seedless is a popular table grape cultivar worldwide because of its appearance, balanced sugar and acidity, and excellent texture. In this study, we assessed variability of volatile compounds in berries among different vineyards and explored its association to maturity at harvest. Volatile composition of Crimson Seedless was analyzed in berries sampled from six vineyards in two adjacent regions. The volatile composition consisted of 43 compounds that were identified in all vineyards tested, and 12 compounds showed variable patterns. This analysis enables differentiation between vineyards based on location of the vineyard, berry acidity, or total soluble solids (TSS), but not according to berry weight. To eliminate environmental or horticultural effects, berries from another vineyard were separated by density into categories of higher and lower maturity (>17.5 Brix and <16.0 Brix, respectively). Clear differences were observed among the volatiles of the two berry groups, corresponding in large part to the pattern observed among the vineyards. Many volatile compounds derived from fatty acid metabolism increased, but linolenic acid derivatives decreased, in association with TSS. Among the volatile compounds identified from the seven vineyards, 1-octanol, methyl hexanoate, and 1-octen-3-ol were associated with higher TSS levels, and (E)-2-hexenal was associated with lower TSS levels. In conclusion, while regional conditions affect berry composition, maturity at harvest is a major, well-defined factor that can account for the observed variability. Compounds that accumulate or decrease in mature berries may serve as additional markers for assessing table grape maturity.