Free and bound terpene profile of recovered minority white grape varieties by GC × GC-TOFMS

Abstract

Climate change presents a significant challenge for actual viticulture. In this context, recovering minority grape varieties can be a crucial strategy to ensure resilience, particularly those capable of maintaining quality and aromatic complexity under water stress. Many of these varieties have characteristics and specific adaptations to their environment, offering an opportunity to diversify vineyards and secure high-quality wine production in the future. In Castilla-La Mancha, the Spanish region with the largest vineyard area, research is underway white minority varieties with promising potential, such as Azargón, Maquías, and Montonera.

The aroma potential of grapes is key to a wine’s aromatic identity, being terpenes one of the most important groups that define this component are terpenes. These are characterized by a low olfactory perception thresholds and pleasant floral aroma and they can exist in two forms: as non-odorous precursors bound to sugar molecules and as volatiles in their free forms. During winemaking and aging, bound terpenes gradually release from the sugar molecules, influencing the wine’s aromatic profile. Grape terpene composition is known for its remarkable diversity, complexity, and structural similarities, where even minor molecular differences can lead to significantly distinct aroma profiles. As a result, the use of precise analytical methods, such as the comprehensive two-dimensional chromatography GCxGC-TOFMS, is essential to investigate and understand the role of terpenes.

Therefore, the objective of this work has focused on these three recovered white viniferas, to determine how two different water regimes, drought with survival irrigation and deficit irrigation (20% ETo), affect their terpene composition in both, free and bound forms. To analyze this, GCxGC-TOFMS was used in combination with enzymatic hydrolysis to release terpenes from their precursor compounds[1].

A total of 80 different terpenes were identified, including myrtenol,β-cyclocitral or β-copaene, among others, with significant variations among grape cultivars and water regimes. In general, a higher concentration was found under the drought regime, suggesting a good adaptability of these cultivars in terms of terpene composition to future climate scenarios. Consequently, this study highlights that these recovered minority grape varieties could be promising candidates for cultivation in semiarid regions, where water availability is limited. This approach would support the sustainability of the wine industry while maintaining the aromatic quality of the wines.

References

[1] Fonseca, D., Martins, N., Garcia, R., Cabrita, M.J (2025). LWT, 215, 117314.