TECHNOLOGICAL POTENTIAL OF PIWI AND COMPARATIVE GRAPE GENOTYPES BASED ON A COMPREHENSIVE ASSESSMENT OF PHYSICOCHEMICAL AND STRUCTURALMECHANICAL CHARACTERISTICS
Abstract
Purpose. To determine the technological potential of the studied grape genotypes through an integrated assessment of physicochemical maturity indices and structural-mechanical characteristics of clusters and berries, and to identify parameters suitable for differentiating primary processing approaches. Methods. Twelve grape genotypes were analysed. Sugar concentration was determined refractometrically, titratable acidity by NaOH titration, and pH potentiometrically; all determinations were performed in triplicate. The study also evaluated cluster mass, berry number, mass of 100 berries and 100 seeds, proportions of stems, skins, seeds and pulp, pulpto- skin ratio, and structural index. Potential alcohol and a sugar-to-acidity maturity index were additionally calculated. Descriptive statistics, Pearson correlation analysis and principal component analysis after z-standardisation were used to summarise the data; owing to the sample size, the multivariate analysis was interpreted as exploratory. Results. Sugar concentration ranged from 160 to 250 g/dm³, titratable acidity from 6.8 to 11.6 g/dm³, pulp proportion from 53.09 to 67.73%, and skin proportion from 12.43 to 29.30%. Zoloden 12.09 showed the highest sugar concentration and structural index, 250 g/dm³ and 6.22, respectively. Sauvignon Rytos showed the highest titratable acidity, pulp-to-skin ratio and pulp proportion: 11.6 g/dm³, 5.45 and 67.73%, respectively. Within the available dataset, the correlation between cluster mass and sugar concentration was r = 0.67, while the first two principal components explained 66.0% of total variability. The scientific novelty consists in the integrated comparison of physicochemical maturity indices with cluster mechanical structure for technological differentiation of the studied grape genotypes. Conclusions. Combining physicochemical and structural-mechanical characteristics provides a more comprehensive assessment of grape technological potential than using individual maturity indices alone. The observed differences in the balance between juice and solid fractions support a differentiated choice of crushing, pressing and juice-to-solids contact regimes. The results provide a basis for subsequent validation of the proposed approach in multi-year studies and controlled microvinifications.
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