Aroma typicity of Timorasso wines: influence of ageing on volatile organic compounds and sensory descriptors

Abstract

‘Timorasso’ is an autochthonous white grape variety from southern Piedmont (Italy) used for producing wines in the Colli Tortonesi product designation of origin (PDO). Over the last decade, there has been a notable rise in its production, due to the increased interest of wine enthusiasts who prized its wine distinctive ageing notes [1].

The aim of this study was to investigate Timorasso wines belonging to vintages 2015-2021, using sensory and analytical methods, through two research stages: i) a preliminary sensory examination of 31 wines by an expert panel to determine Timorasso wine relevant descriptors; ii) a detailed analysis of free volatile organic compounds (VOCs) in a selected subsample of 18 wines, quantifying varietal VOCs (terpenes and C₁₃-norisoprenoids) and fermentation-related VOCs (esters, higher alcohols, fatty acids) by HS-SPME/GC-MS techniques, whereas low molecular weight sulphur compounds (LMWSCs) were analysed by HS-GC-PFPD [2]. This stage also included a descriptive sensory analysis (DA) with a trained panel on pre-defined relevant descriptors.

The experts panel most frequently characterized Timorasso wines with “Kerosene” (27.9% of citation), “White flowers” (15.5%) and “Yellow pulp fruits” (14.8%) categories. “Kerosene”, “Balsamic” (10.8%), and “Empyreumatic” (5.5%) were positively correlated with aroma typicity (rated by the expert panel) of Timorasso wines, and they were found to be particularly relevant for wines aged for 5-6 years. Fruity-floral notes characterized the young wines (2021) but were not considered typicity markers. The VOCs analysis of 18 selected wines confirmed that the younger wines (2021) had significantly higher acetate esters content (and “Fruity” descriptors intensity in the DA). Six terpenes were detected, but in moderate concentrations and usually below sensory thresholds. C₁₃-Norisoprenoids found were β-damascenone, vitispirane, and 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN). TDN was detected above the recognition threshold (10-12 ng/L) in some Timorasso wines [3], which is remarkable because it has previously been found mainly in Riesling wines. Higher concentrations of TDN were noticed in older wines (2017 vintage), which also showed a higher intensity of “Kerosene/beeswax” descriptor according to the DA. The “Empyreumatic” descriptor in the DA was relevant for the 2019 vintage. Some LMWSCs may be involved in the higher empyreumatic scores of certain wines. Understanding the chemical markers may help future research on the winemaking approaches to better express the Timorasso wines varietal typicity.

References

[1] Laureati, M., Appiani, M., Cattaneo, C., Rabitti, N. S., Verveur, Z., Bergaglio, S., & Valentin, D. (2023). OENO One, 57(4), 1-14.

[2] Tarasov, A., Garzelli, F., Schuessler, C., Fritsch, S., Loisel, C., Pons, A., Patz, C.-D., Rauhut, D., & Jung, R. (2021). Molecules, 26(20), 6256.

[3] Tarasov, A., Giuliani, N., Dobrydnev, A., Schuessler, C., Volovenko, Y., Rauhut, D., & Jung, R. (2020). Foods, 9(5), 606.