 IVES 9 IVES Conference Series 9 Quality of Merlot wines produced from terraced vineyards and vineyards on alluvial plains in Vipava valley, Slovenia (pdo)

Quality of Merlot wines produced from terraced vineyards and vineyards on alluvial plains in Vipava valley, Slovenia (pdo)

Abstract

AIM: Different factors affect the style and quality of wine and one of the most important are environmental factors of vineyard location. The aim of this study was to compare the quality of Merlot wines produced from grapes growing on skeletal and dry soils of terraced vineyards and deep loamy soils of alluvial plains of Vipava Valley, a warm climate winegrowing district in Slovenia.

METHODS: Five vineyards on terraces and five on alluvium plains were chosen. Viticulture parameters such as number of buds, number of clusters and leaf area on each vine were unified in 2019 and 2020 as described in Sivilotti et al. (2020). Stem water potential (SWP) was measured during the season (Deloire and Heyns, 2011). 5 kg of grapes were sampled in triplicates at the time of grape maturity. Basic physicochemical parameters of grapes were determined before microvinification. Microvinifications were analysed after alcoholic and malolactic fermentation. Concentration of total phenols (TP), total anthocyanins (TA), high (HMWP) and low molecular weight (LMWP) proanthocyanidins (PAS) were determined spectrophotometrically as described in Rigo et al. (2000). Moreover, structural characteristics of PAs in wines, i.e. mean degree of polymerisation (mDP), percentage of galloylaton (%G) and percentage of prodelphinidins (%P) were determined by UHPLC-DAD-MS/MS as described in Lisjak et al. (2019) and in Sivilotti et al. (2020). Esters were analysed by GC-MS (Bavčar and Baša Česnik, 2011) and higher alcohols by GC-FID (Bavčar et al., 2011).

RESULTS: SWP was more negative on terraces. According to basic physico chemical parameters and darker seed colour, grapes from terraces showed advanced ripening in comparison to grapes grown in alluvial plains. Wines from terraces had higher concentrations of TA, TP, HMWP, ash and total dry extract in comparison to wines from alluvial plains and PAs reported higher %G. Furthermore, aromatic profiles of wines were also different. In general, higher concentrations of higher alcohols and lower concentrations of esters were detected in wines from terraces.

CONCLUSIONS:

The Merlot wines from grapes sampled in terraced vineyards differed in chemical composition from those from alluvial plains. In general, wines from terraces had higher polyphenol content, some quality parameters such as ash and total dry extract, structural differences of grape tannins and different profile of some aroma compounds

DOI:

Publication date: September 10, 2021

Issue: Macrowine 2021

Type: Article

Authors

Alenka Mihelčič

Agricultural Institute of Slovenia, Hacquetova ulica 17, 1000 Ljubljana, Slovenia ,Andreja VANZO, Agricultural Institute of Slovenia, Hacquetova ulica 17, 1000 Ljubljana, Slovenia Borut VRŠČAJ, Agricultural Institute of Slovenia, Hacquetova ulica 17, 1000 Ljubljana, Slovenia Paolo SIVILOTTI, University of Udine, via delle Scienze 206, 33100 Udine, Italy Klemen LISJAK, Agricultural Institute of Slovenia, Hacquetova ulica 17, 1000 Ljubljana, Slovenia

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Keywords

terraces, alluvial plains, soil, stem water potential, wine quality, polyphenols, volatile compounds

Citation

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Climate change and rising atmospheric carbon dioxide concentration is a concern for agriculture, including viticulture. Studies on elevated carbon dioxide have already been on grapevines, mainly taking place in greenhouses using potted plants or using field grown vines under higher CO2 enrichment, i.e. >650 ppm. The VineyardFACE, located at Hochschule Geisenheim University, is an open field Free Air CO2 Enrichment (FACE) experimental set-up designed to study the effects of elevated carbon dioxide using field grown vines (Vitis vinifera L. cvs. Riesling and Cabernet Sauvignon). As the carbon dioxide fumigation started in 2014, the long term effects of elevated carbon dioxide treatment can be investigated on berry ripening parameters and fruit metabolic composition.
The present study aims to investigate the effect on fruit composition under a moderate increase (+20%; eCO2) of carbon dioxide concentration, as predicted for 2050 on both Riesling and Cabernet Sauvignon. Berry composition was determined for primary (sugars, organic acids, amino acids) and secondary metabolites (anthocyanins). Special focus was given on monitoring of berry diameter and ripening rates throughout three growing seasons. Compared to previous results of the early adaptative phase of the vines [1], our results show little effect of eCO2 treatment on primary metabolites composition in berries. However, total anthocyanins concentration in berry skin was lower for eCO2 treatment in 2020, although the ratio between anthocyanins derivatives did not differ.
[1] Wohlfahrt Y., Tittmann S., Schmidt D., Rauhut D., Honermeier B., Stoll M. (2020) The effect of elevated CO2 on berry development and bunch structure of Vitis vinifera L. cvs. Riesling and Cabernet Sauvignon. Applied Science Basel 10: 2486