Instrumental texture analysis parameters as winegrapes varietal markers and ripeness predictors.

The texture parameters of three red grape varieties (Mencía, Brancellao and Merenzao) cultivated in Galician vineyards (Northwest Spain) were determined. Different ripening stages (A: 176 ± 8 g/l reducing sugars; B: 193 ± 8 g/l reducing sugars; C: 210 ± 8 g/l reducing sugars; D: 227 ± 8 g/l reducing sugars) were also considered. Principal component analysis (PCA) was performed for a better understanding of the differences found among grapes according to variety and ripening stage based on the skin and berry texture parameters. The parameters differentiating varieties were the skin break force and energy measured on the lateral side, whereas ripening stages can be classified on the basis of berry cohesiveness. The hardest berry skin was associated with Merenzao variety with break skin force values comprised between 0.752 - 0.811 N and break skin energy between 0.715 and 0.790 mJ for A and B ripening stages respectively. Instead Brancellao variety presented the softest skin with break skin force values ranged from 0.521 to 0.562 N and break skin energy from 0.407 to 0.475 mJ for A and B ripening stages. Ripeness grade increased with the berry cohesiveness for all the varieties studied.