Aromatic maturity is a cornerstone of terroir expression in red wine

Harvesting grapes at adequate maturity is key to the production of high-quality red wines. Viticulturists, enologists, and wine makers define several types of maturity, including physiological maturity, technological maturity, phenolic maturity, and aromatic maturity. Physiological maturity is a biological concept. Technological maturity and phenolic maturity are relatively well documented in the scientific literature, being linked to quantifiable compounds in grape must. Articles on aromatic maturity are scarcer. This is surprising, because aromatic maturity is, probably, the most important of the four in determining wine quality and typicity, including terroir expression, i.e.  the identifiable taste of wine in relation to its origin. Optimal terroir expression can be obtained when technological, phenolic, and aromatic maturity are reached at the same time, or within a short time frame. This is more likely to occur when the ripening takes place under mild temperatures, neither too cool, nor too hot. Aromatic expression in wine can be driven, in order from low to high maturity, by green, herbal, spicy, floral, fresh fruit, ripe fruit, jammy fruit, dried fruit, candied, or cooked fruit aromas. Green and cooked fruit aromas are not desirable in red wines, while the levels of other aromatic nuances contribute to the typicity of the wine in relation to its place of origin. Wines produced in cool climates, or on cool soils in temperate climates, are likely to express herbal or fresh fruit aromas, while wines produced under warm climates, or on warm soils in temperate climates, may express ripe fruit, jammy fruit, or candied fruit aromas. This article reviews the state of the art of compounds underpinning the aromas of wines obtained from grapes harvested at different stages of maturity. Advances in the understanding of how aromatic maturity shapes terroir expression and how it can be manipulated by variety choices and management practices, under current and future climatic conditions, are shown. Early ripening varieties perform better in cool climates and late ripening varieties in warm climates. Additionally, maturity can be advanced or delayed by different canopy management practices or training systems. Timing of harvest also impacts aromatic expression of the produced wine. Gaps in the literature are highlighted to guide future directions of research.