 IVES 9 IVES Conference Series 9 Impact of the pre-fermentative addition of enological adjuvants on the development of UTA in wines

Impact of the pre-fermentative addition of enological adjuvants on the development of UTA in wines

Abstract

AIM: During alcoholic fermentation and wine aging, indole-3-acetic acid (IAA) can degrade into 2-aminoacetophenone (AAP). The presence of reasonable amount of AAP in wines is regarded as the main cause of untypical ageing defect (UTA) described by aroma descriptors such as “acacia blossom”, “furniture polish”, “wet wool”, “mothball”, or “fusel alcohol” [1, 2]. This study aims to evaluate the effectiveness of different oenological adjuvants (ascorbic acid, glutathione, ellagic tannin, gallotannin and grape tannin) added to must in pre-fermentation for preventing the possible development of UTA. In addition, a high-resolution suspect-screening approach was performed to evaluate the kinetics of formation and consumption of metabolites formed during the oxidative degradation of IAA into AAP.

METHODS: Johannitter, Pinot Blank, Pinot Gris and Riesling musts were separately added with each of the 5 adjuvants (GrT, EgT, GaT, ASC and GSH), fermented and finally added of sulfur dioxide. The free and conjugated IAA forms were qualified or quantified in wine at the end of the fermentation and the AAP was finally quantified after a period of forced ageing (6 days at 40 °C). Quantification was performed using a HPLC coupled with a high-resolution mass spectrometer (UHPLC-HQOMS) using a biphenyl column (3×150 mm, 2.7 µm) with formic acid 2% and acetonitrile as eluents [3]. The quantification limits ranged from 0.25 to 2 μg/L, excepted for AAP that had a quantification limit of 0.02 μg/L. For qualitative analyses, homemade standards of indole-acetic acid-2-sulfonate (IAA-SO3H) and of metabolites produced by oxidative chemical reaction of IAA to AAP (radical cation, FAP, FAPOP and Ox-IAA) were prepared. The IAA-hexoside RT was studied with a full mass/all ion fragmentation/NL data dependent-MS2 (Full MS/AIF/NL dd-MS2) experiment in positive ion mode [4].

RESULTS: Ascorbic acid has been confirmed as the most appropriate antioxidant adjuvant which can be used for UTA defect prevention. With an almost comparable effect, gallotannin also did not show AAP productions greater than 1 µg/L. Over 80% of the variability of potential AAP formation in wines was explained by an ANCOVA model, which was used to predict the possible AAP production considering the varieties, treatments and IAA content in young wine as known variables.

CONCLUSIONS

Thanks to high resolution mass spectrometry, we were able to qualify and quantify different precursors and metabolites that take part in the development of UTA, allowing a better understanding of the mechanisms of AAP formation and the adjuvants actions involved in the wine protection.

DOI:

Publication date: September 14, 2021

Issue: Macrowine 2021

Type: Article

Authors

Tiziana Nardin

Technology Transfer Centre, Fondazione Edmund Mach, San Michele all’Adige, Italy,Tomas Roman, Susanne Dekker, Roberto Larcher Technology Transfer Centre, Fondazione Edmund Mach, San Michele all’Adige, Italy

Contact the author

Keywords

uta, AAP, HRMS

Citation

Permanent cover cropping with reduced tillage increased resiliency of wine grape vineyards to climate change

Majority of California’s vineyards rely on supplemental irrigation to overcome abiotic stressors. In the context of climate change, increases in growing season temperatures and crop evapotranspiration pose a risk to adaptation of viticulture to climate change. Vineyard cover crops may mitigate soil erosion and preserve water resources; but there is a lack of information on how they contribute to vineyard resiliency under tillage systems. The aim of this study was to identify the optimum combination of cover crop sand tillage without adversely affecting productivity while preserving plant water status. Two experiments in two contrasting climatic regions were conducted with two cover crops, including a permanent short stature grass (P. bulbosa hybrid), barley (Hordeum spp), and resident vegetation under till vs. no-till systems in a Ruby Cabernet (V. vinifera spp.) (Fresno) and a Cabernet Sauvingon (Napa) vineyard. Results indicated that permanent grass under no-till preserved plant available water until E-L stage 17. Consequently, net carbon assimilation of the permanent grass under no-till system was enhanced compared to those with barley and resident vegetation. On the other hand, the barley under no-till system reduced grapevine net carbon assimilation during berry ripening that led to lower content of nonstructural carbohydrates in shoots at dormancy. Components of yield and berry composition including flavonoid profile at either site were not adversely affected by factors studied. Switching to a permanent cover crop under a no-till system also provided a 9% and 3% benefit in cultural practices costs in Fresno and Napa, respectively. The results of this work provides fundamental information to growers in preserving resiliency of vineyard systems in hot and warm climate regions under context of climate change.

Local adaptation tools to ensure the viticultural sustainability in a changing climate

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Effect of fertigation strategies to adapt PGI Côtes de Gascogne production to hot vintage

The development of fertigation could be a possible solution to adapt PGI Côtes de Gascogne (south-western France) wine production to climate change. The goal would be to limit the negative effects of water stress on yield performance expectation (around 15 tons per hectare) and to make the use of fertilizers more efficient. This study aimed to compare the effects of three strategies of water and minerals supply on grapes and wines qualities. Two fertigation practices were compared to a rainfed control which is the current standard of the local grape growing production. The fertilizers (nitrogen and potassium) were (i) fully brought by irrigation pipe during the season, (ii) partially brought by irrigation pipe and partially on the soil or (iii) fully brought on the soil at the beginning of the season for the non-irrigated control (local standard). The trial was run on cv. Colombard trained on spur pruned with vertical shoot positioning system on a sandy-silty-clay soil over the 2020 vintage which was particularly hot for the region. Moderate to strong water deficit appeared during the growing period of the berries and held on after veraison. Irrigation strategies allowed for maintaining grapevine without water deficit and being significantly different from the control water status. Grapevine with fully or partial fertigation strategies produced 25% more yield mainly due to the increase of the bunch weight. Also, the fully fertigation showed the best ratio between yield and maturity and brought 30% less of fertilizers (both nitrogen and potassium) than the two other strategies. Finally, the analysis of aromatic compounds in Colombard wines, varietal thiols family, showed the same level of concentrations for the 3 treatments, confirming that the yield performance did not impact the aromatic potential in this trial.

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