Macrowine 2021
IVES 9 IVES Conference Series 9 Effect of SO2, GSH and gallotannins on the shelf-life of a cortese white wine

Effect of SO2, GSH and gallotannins on the shelf-life of a cortese white wine

Abstract

AIM: Studying the effect of the addition of reduced glutathione (GSH) and/or gallotannins at bottling to limit the use of SO2 in white winemaking.

METHODS: Two aliquots of a Cortese white wine were oxygenated respectively to 5.5 ppm (experiment A) and 3 ppm (experiment B) of O2. The additives (SO2, gallotannins, GSH) were added at bottling at 2 levels following a full factorial plan: 20-60 mg/L of free SO2; absence/presence (40 mg/L) of tannins, absence/presence (20 mg/L) of GSH.

Experiment A was monitored during 12 months of storage (colour, polyphenolic composition, GSH, free and total SO2); the samples of experiment B were analyzed and the sensory profiles were defined 15 months after bottling. The oxygen consumption rate (OCR) was measured with a luminescence-based technology.

RESULTS: SO2 was the only additive that increased OCR and decreased colour intensity, without any effect on polyphenols content and HCTA. The presence of GSH limited the oxidative losses of SO2, mostly in the wines with higher SO2 levels. The effect of GSH decreased over time: after 8 months GSH was only present in traces. A higher SO2 content, though not statistically significant, was  still observed 12 months after bottling in the samples with both tannins and GSH. The sensory analyses distinguished the samples for the colour and some olfactory descriptors. The samples with GSH had more intense licorice notes and lower pinapple notes.

CONCLUSIONS

The oxidative browning of wines during bottle storage was limited only by the residual presence of free SO2: the colour intensity and the free SO2 content are inversely correlated. The addition of GSH, alone or together with tannins, reduced the losses of free SO2. The low efficacy of GSH could be due to the low dosage used.

DOI:

Publication date: September 14, 2021

Issue: Macrowine 2021

Type: Article

Authors

Silvia Motta 

Consiglio per la ricerca in agricoltura e l’analisi dell’economia agraria – Centro di Ricerca Viticoltura ed Enologia, via P. Micca 35, 14100 Asti, Italy,Maria Carla Cravero*, Massimo Guaita*, Maria Rosa Lottero*, Antonella Bosso* *Consiglio per la ricerca in agricoltura e l’analisi dell’economia agraria – Centro di Ricerca Viticoltura ed Enologia, via P. Micca 35, 14100 Asti, Italy

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Keywords

oxygen, glutathione, tannins, SO2, white wine

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Current climate change in the Oplenac wine-growing district (Serbia)

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Macrowine 2021
IVES 9 IVES Conference Series 9 Effect of SO2, GSH and gallotannins on the shelf-life of a cortese white wine

Effect of SO2, GSH and gallotannins on the shelf-life of a cortese white wine

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1H-NMR-based Metabolomics to assess the impact of soil type on the chemical composition of Mediterranean red wines

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When to initiate irrigation is a critical annual management decision that has cascading effects on grapevine productivity and wine quality in the context of climate change. A multi-site trial was begun in 2021 to optimize irrigation initiation timing using midday stem water potential (ψstem) thresholds characterized as departures from non-stressed baseline ψstemvalues (Δψstem). Plant material, vine and row spacing, and trellising systems were concomitant among sites, while vine age, soil type, and pruning systems varied. Five target Δψstem thresholds were arranged in an RCBD and replicated eight times at each site: 0.2, 0.4, 0.6, 0.8, and 1.0 MPa (T1, T2, T3, T4, and T5, respectively). When thresholds were reached, plots were irrigated weekly at 70% ETc. Yield components and berry composition were quantified at harvest. To better generalize inferences across sites, data were analyzed by ANOVA using a mixed model including site as a random factor. Across sites, irrigation was initiated at Δψstem = 0.24, 0.50, 0.65, 0.93, and 0.98 MPa for T1, T2, T3, T4, and T5, respectively. Consistent significant negative linear trends were found for several key yield and berry composition variables. Yield decreased by 12.9, 15.9, 19.5, and 27.4% for T2, T3, T4, and T5, respectively, compared to T1 (p < 0.0001) across sites that were driven by similarly linear reductions in berry weight (p < 0.0001). Comparatively, berry composition varied little among treatments. Juice total soluble solids decreased linearly from T1 to T5 – though only ranged 0.9 Brix (p = 0.012). Because producers are paid by the ton, and contracts simply stipulate a target maturity level, first-year results suggest that there is no economic incentive to induce moderate water deficits before irrigation initiation, regardless of vineyard site. Subsequent years will further elucidate the carryover effects of delaying irrigation initiation on productivity over the long term.

Use of multispectral satellite for monitoring vine water status in mediterranean areas

The development of new generations of multispectral satellites such as Sentinel-2 opens possibilities as to vine water status assessment (Cohen et al., 2019). Based on a three years field campaign, a model of Stem Water Potential (SWP) estimation on vine using four satellite bands in Red, Red-Edge, NIR and SWIR domains was developed (Laroche-Pinel et al., 2021). The model relies on SWP field measures done using a pressure chamber (Scholander et al., 1965), which is a common, robust and precise method to assess vine water status (Acevedo-Opazo et al., 2008). The model was mainly developed from from SWP measures on Syrah N (Laroche Pinel E., 2021).

A large scale monitoring was organized in different vineyards in the Mediterranean region in 2021. 10 varieties amongst the most represented in this area were monitored (Cabernet sauvignon N, Chardonnay B, Cinsault N, Grenache N, Merlot N, Mourvèdre N, Sauvignon B, Syrah N, Vermentino B, Viognier B). The model was used to produce water status maps from Sentinel-2 images, starting from the beginning of June (fruit set) up to September (harvest). The average estimated SWP for each vine was compared to actual field SWP measures done by wine growers or technicians during usual monitoring of irrigation programs. The correlations between mean estimated SWP and mean measured SWP were at the same level than expected by the model. (Laroche Pinel, 2021) The general SWP kinetics were comparable. The estimated SWP would have led to same irrigation decisions concerning the date of first irrigation in comparison with measured SWP.

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Cohen, Y., Gogumalla, P., Bahat, I., Netzer, Y., Ben-Gal, A., Lenski, I., … Helman, D. (2019). Can time series of multispectral satellite images be used to estimate stem water potential in vineyards? In Precision agriculture ’19, The Netherlands: Wageningen Academic Publishers, pp. 445–451.
Laroche-Pinel, E., Duthoit, S., Albughdadi, M., Costard, A. D., Rousseau, J., Chéret, V., & Clenet, H. (2021). Towards vine water status monitoring on a large scale using sentinel-2 images. remote sensing, 13(9), 1837.
Laroche-Pinel,E. (2021). Suivi du statut hydrique de la vigne par télédétection hyper et multispectrale. Thèse INP Toulouse, France.
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