Varietal Compounds in Grapes: A Comprehensive Review.

Volatile compounds are major determinants of grape aroma, varietal typicity, and sensory quality. This review critically summarizes current knowledge on grape varietal volatile compounds, with emphasis on their structural diversity, biosynthetic origin, sensory relevance, and analytical characterization. The evidence reviewed indicates that grape aroma potential results from the combined influence of cultivar-dependent metabolism, precursor availability, berry development, environmental conditions, and viticultural practices. Terpenes and C13-norisoprenoids are key contributors to varietal aroma because they impart characteristic sensory notes, including floral, fruity, and citrus notes, which contribute to the aromatic identity and typicity of grape cultivars. Their accumulation in grape berries is controlled by the activity of specific biosynthetic pathways and by the formation and transformation of aroma precursors, which can be further modulated by climate, vineyard management, and grape maturity. Therefore, understanding the biochemical and environmental regulation of these compounds is essential for interpreting varietal aroma expression and improving the flavor quality of grapes. Advances in extraction and analytical methodologies have improved the characterization of grape volatile profiles and aroma precursors in complex matrices. However, differences in sample preparation, extraction procedures, and quantification approaches still limit comparability among studies. Greater methodological harmonization, together with the integration of biochemical, environmental, and compositional data, is therefore needed to better assess grape aroma potential and support strategies for improving grape and wine quality. This review provides a scientific basis for researchers, winegrowers, and winemakers seeking to understand and manage grape varietal volatile composition.