UV-VIS-NIR spectroscopy as a tool for predicting volatile compounds in grape must

Abstract

The wine sector is one of the most significant industries worldwide, with Spain being a leading country in wine production and export. A key factor in wine quality is its aroma, which is directly influenced by the volatile compounds present in the grape, with terpenes being among the most significant contributors. These compounds are responsible for the floral and fruity aromas characteristic of wine (1). Analytical methods for grape and wine analysis, particularly for volatile metabolites, often involve costly instrumentation and labor-intensive extraction procedures. In contrast, vibrational spectroscopy techniques, such as ultraviolet-visible (UV-Vis), and near-infrared (NIR) spectroscopy, have gained recognition as valuable analytical tool due to their simplicity, speed, and non-destructive nature. Currently, there is a notable scarcity of studies presenting accurate predictive models for terpene compounds in grape must (2). The objective of this work is to ascertain the viability of applying a wide range spectrum spectroscopy (UV-Vis-NIR) to develop precise models capable of predicting the terpene composition of the grape must. Our investigation specifically targets on the determination of glycosylated terpenes, including Z-8-hydroxylinalool, cis-furan linalool oxide, cis-pyran linalool oxide, geraniol (trans), HO-trienol (3,7-dimethyl-1,5,7-octatrien-3-ol), linalool, trans-furan linalool oxide, trans-pyran linalool oxide, and α-terpineol. Partial Least Squares Regression (PLSR) was employed to construct models. The results showed satisfactory predictive models for linalool (r² = 0.8; RMSE = 0.89), geraniol (r² = 0.8; RMSE = 8.63), and α-terpineol (r² = 0.84; RMSE = 2.56). The remaining predictive models developed showed acceptable coefficients of determination. UV region was identified as the most relevant region for the construction of the PLS-R models. These findings highlight the potential of this innovative technique to revolutionize the wine industry by enabling faster and cost-effective analysis of volatile compounds in must, thereby optimizing the winemaking process and improving product traceability.

References

[1] Vilanova, M., García, M., & González, M. (2012). GC-MS analysis of volatile compounds in grapes. Journal of Food Science, 77(3), C215–C220

[2] Boido, E., Fariña, L., Carrau, F., Dellacassa, E., & Cozzolino, D. (2013). Characterization of Glycosylated Aroma Compounds in Tannat Grapes and Feasibility of the Near Infrared Spectroscopy Application for Their Prediction. Food Analytical Methods, 6(1), 100-111