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

Silvia Motta1, Maria Carla Cravero1, Massimo Guaita1, Maria Rosa Lottero1, Antonella Bosso1, Antonio Tirelli2
1 Consiglio per la ricerca in agricoltura e l’analisi dell’economia agraria - Centro di Ricerca Viticoltura ed Enologia, Italy
2 Dipartimento di Scienze per gli Alimenti, la Nutrizione e l’Ambiente (DeFENS), Università degli Studi di Milano, Italy

Email contact: silvia.motta[@]crea.gov.it

 

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.

 

References:

Danilewicz, J C, 2007. Interaction of sulfur dioxide, polyphenols, and oxygen in a wine-model system: Central role of iron and copper. Am J Enol Vitic 58: 53–60.

Danilewicz J C et al., 2008 Mechanism of interaction of polyphenols, oxygen, and sulfur dioxide in model wine and wine Am J Enol Vitic 59:128-136.

Danilewicz J C & Wallbridge J P, 2010. Further studies on the mechanism of interation of polyphenols, oxygen, and sulfite in wine. Am J Enol Vitic 61:166-175.

Danilewicz J C, 2011. Mechanism of autoxidation of polyphenols and participation of sulfite in wine: key role of iron. Am J Enol Vitic 62: 319-326

Danilewicz J C, 2013. Reactions involving iron in mediating catechol oxidation in model wine Am J Enol Vitic 64: 316-324

Du Toit W J et al., 2006, Oxygen in Must and Wine: A Review. S Afr J Enol Vitic 27: 76-94

Motta S, 2014. Effect of Reductive Pressing on the Content of Reduced Glutathione and Phenols in the Musts of Four Italian Cultivars. Am J Enol Vit, in press. ajev.13087, 2014, American Society for Enology and Viticulture

Silva Ferreira A C et al., 2003. Identification of key odorants related to the typical aroma of oxidation-spoiled white wines. J Agric Food Chem 51: 1377−1381

Published on 06/12/2018
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