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By Vania Sáez, Doreen Schober, Álvaro González and Panagiotis Arapitsas

Chile is a very long and narrow country with the Andes Mountains to the east and Pacific Ocean to the west. This unique geographical morphology encompasses a wide range of wine-growing conditions influenced by the coastal range, offering a diverse climatic characteristic for viticulture. Most of the vineyards are placed between 30°S to 36°S, where is possible find diverse climatic conditions from semi-arid according to elevation in the north central zone, to dominant Mediterranean-type in the central zone, where it is possible to identify important differences in climatic conditions in a single wine region [Montes et al 2012]. Chilean winemakers take advantage of soil and climate variability to produce wines with different signatures and styles, even if they start from the same grape cultivar. 35% of Chilean wine production with origin appellation are Cabernet Sauvignon, which  correspond to the 40% of cultivated red grape production area, and more of 90% of this cultivar are placed between Maipo and Maule Valleys in the central zone (Figure 1) [SAG]. Such a huge diversity in viticultural characteristics and conditions led to the production of numerous quality and character wines, from Super Premium to Standard quality wines. However, there is a lack of knowledge concerning the metabolites that are responsible for this diversity and therefore a lack of tools to improve and promote the Chilean Cabernet Sauvignon.

To study the quality diversity in the produced Cabernet Sauvignon in Chile, a consortium was built between the Center for Research and Innovation of Viña Concha y Toro in Chile and the research center of Fondazione Edmund Mach in Italy. The aim of the consortium was to study the difference at a metabolomic level of 150 experimental monovarietal wines produced by grapes originated by 8 different Chilean valleys (Limarí, Aconcagua, Maipo, Cachapoal, Colchagua, Curicó, Maule, Itata), which were divided according to a company quality categorization into two major categories (Premium and Standard) and each of them in two subcategories (Super-premium, Premium, Standard plus and Standard) (Figure 1).

Figure 1: (A) Grape distribution of sampled vineyards from different Chilean valleys, (B) Cabernet Sauvignon vineyards ,(C) Experimental winery from Center of Research and Innovation (CRI) of Viña Concha y Toro. Vineyard photographs were kindly provided by Sebastian Vargas Soto, Lider I+D+i in viticulture and enology from CRI.

The main novelty of this project outcomes was that it underlined the importance of the nitrogen-containing metabolites in discriminating the Chilean Cabernet Sauvignon wines according to their quality. This group of biomarkers included amino acids and several small peptides. In particular, proline, leucine, phenylalanine, α-aminoadipic acid,  glutathione S-sulfonated characterized the premium quality Cabernet Sauvignon wines (Figure 2). This publication takes part in a series of recently published papers [Sherman et al 2020, Zhou et al 2021], which connect small peptides and wine sensorial character, and underline the importance to investigate further this future to Chilean wines too.

On the other hand, the role of polyphenols in wine quality is well described in the literature, especially regarding the color (anthocyanins/pigments), taste (tannins/proanthocyanidins) and longevity/aging potential (= i.e., protection against oxidations). In fact, our results demonstrated that Premium wines were richer in anthocyanins and their corresponding pigments, proanthocyanins, and other flavonoids (Figure 2). Therefore, the ecosystem and viticulture practices of the Premium wines valleys favored the biosynthesis of the above-mentioned metabolites. On the contrary, Standard quality wines were richer in stilbenes, which are well-known for having an increased rate of biosynthesis in grape vines as response to various biotic and abiotic stresses (climate, viticulture practices, microorganisms etc). Thus, a plausible explanation is the stress in the Standard quality wines vineyards directed the metabolism of the vine/grape towards stilbenes instead to flavonoids, and the produced wines are less coloured (anthocyanins), with fewer body (tannins), and minor longevity potential (antioxidants). To reinforce this hypothesis came the measurement of higher amounts of sulfonated metabolites in Standard quality wines, like the sulfonated tryptophol, sulfonated indoles, and sulfonated flavanols (Figure 2).

Figure 2: Schematic representation for annotated biomarkers and markers for standard and premium Chilean Cabernet Sauvignon wines.

The use of a state-of-the-art metabolomics/untargeted protocol, make it possible to gain new insights into the Chilean Cabernet Sauvignon character, understand better its quality and diversity, and open new research pathways in wine science.  

See the original article for detailed information on this research here:

Sáez, S.; Schober, D.; González, A.; and Arapitsas, P. “LC–MS-Based Metabolomics Discriminates Premium from Standard Chilean cv. Cabernet Sauvignon Wines from Different Valleys” Metabolites (2021) 11(12), 829. https://doi.org/10.3390/metabo11120829

Vania Sáez: She carried out a postdoctoral research in the Fondazione Edmund Mach (Italy) within the Framework of Becas Chile ID 74190033 from ANID, Chile. Her research work is mainly focused in agroindustry, including the revalorization of winemaking byproducts and food analysis.  

Doreen Schober: She used to be a postdoctoral researcher in The Center for Research and Innovation of Viña Concha y Toro. Her focus has been on investigation in viticulture and enology ever since, including research on vineyard management, fermentation microbiology and the development of analytical and sensorial methods. Recently she has begun to be involved with topics in organic and sustainable production.

Panagiotis Arapitsas: He is assistant professor at the University of West Attica (Greece) and researcher at Fondazione Edmund Mach (Italy). His research is focused on the wine and food metabolome investigation, by developing analytical protocols, data treatment and biomarker identification and hypotheses validation.

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