Wine metabolomics and sensory profile in relation to terroir: A case study focusing on different wine-growing areas of Piacenza Province (Italy)

Aim: In this work, we have optimized a robust methodology for investigating possible correlations between the phytochemical profile of wine and the terroir (including the climate), considering the specific wine-growing area. In particular, the untargeted metabolomic and sensorial profiles of Gutturnio DOC commercial wines (both still and “frizzante” types) from different production areas in the Piacenza province were determined. The geographical areas taken into consideration for this study consisted in Val Tidone, Val Nure and Val d’Arda.

Methods and Results: A metabolomic approach based on ultra-high-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UHPLC-ESI-QTOF) was used to investigate the untargeted phenolic profiles of “Gutturnio” DOC wines from different growing areas, namely Val Tidone, Val Nure, and Val d’Arda, located in Piacenza province (Emilia Romagna region, Italy, 45 °Lat N). In this regard, eight “Gutturnio” wines (both still and “frizzante”) from the same vintage (2016) were compared in order to highlight the impact of terroir on their chemical composition and sensory profile. Besides, correlations between wine chemical composition and climatic data of each of the three valleys have been investigated. The highest content of phenolic acids was recorded in still Gutturnio wines from Val Tidone and Val d’Arda (i.e., 389.9 and 388.2 mg/L, respectively). Both unsupervised and supervised multivariate statistical analyses (hierarchical clustering, principal component analysis, and partial least squares discriminant analysis) of metabolomics-based data allowed the different samples to be clearly discriminated according to the corresponding growing-areas. Interestingly, the most discriminant compounds allowing sample grouping belonged to phenolic acids (such as isomeric forms of diferuloylquinic acid) and alkylphenols (such as 5-heptadecylresorcinol). Besides, the Venn diagram analysis revealed seven common markers belonging to both conditions under investigation (i.e., terroir and winemaking practices). Besides, strong correlations were outlined between flavonoids, lignans, and phenolic acids with climatic data. Finally, sensory analysis allowed clear discrimination between still vs” frizzante” Gutturnio wines. 

Conclusions: 

The untargeted phenolic profiling was able to discriminate Gutturnio wine samples according to both terroir and vinification methods. Also, strong correlation coefficients were outlined when considering polyphenol profiles and climatic data, although further ad-hoc studies are needed to confirm this occurrence.

Significance and Impact of the Study: Preliminary and potential correlations have been identified between the phytochemical profile and sensorial quality of Gutturnio wines as related to both growing areas and vinification type.