In this study an ultraviolet (UV) light processing was evaluated as a viable alternative for the microbiological stabilization of wines. Indeed, sulphur dioxide (SO2) is associated with health troubles in sensitive subjects, and the wine industry is looking for new innovative techniques that can help reducing SO2 levels in wines, without modifying their chemical and sensory properties. Industrial-scale trials were carried out by using the novel turbulent-flow reactor SurePure (Milnerton, South Africa) consisting of 40 UV lamps that emit at the germicidal wavelength of 253.7 nm (UV-C). Three wines, i.e. red (Montepulciano d’Abruzzo), rosé (Schiava), and white (Pinot gris) wines, were exposed to UV-C dosages ranging from 0 kJ/L (control) to 1 kJ/L, at a constant flow rate of 4000 L/h. All wines contained low SO2 levels. The effect of Sure Pure treatment on the microbial levels in the white and rosé wines was remarkable, since a 99.99% reduction of yeasts, acetic and lactic acid bacteria was achieved using UV-C dosages < 0.5 kJ/L. On the contrary, a dosage of 1 kJ/L resulted in an average log10 microbial reduction of 1-2 in Montepulciano wine. The level of reduction in microbial counts depended largely on UV-C dosage and absorptive properties of wine, being UV light more effective in treating white and rosé than red wines. Therefore, the reduction in microbial counts depended on both UV-C dosage and level of UV-absorbing compounds in wine. Preliminary tests on wines subjected to the higher UV-C dosage tested indicated no changes in the routine chemical analysis of wines (e.g. ethanol concentration, pH, volatile acidity, color intensity) in comparison with the controls. In addition, analysis of the aroma profile by gas chromatography and sensory evaluation tests did not find significant differences between UV-C irradiated (1 kJ/L) and control wines. In conclusion, the results indicated that a low dosage UV-C treatment holds considerable promise in winemaking for white and rosé wine, as an alternative technology to limit the use of SO2, without affecting smell and taste of wines.
Effect of UV-C light irradiation on the quality and microbial population of Italian red, rosé and white wines
FRACCHETTI, Fabio;LORENZINI, Marilinda;FELIS, Giovanna;TORRIANI, Sandra
2012-01-01
Abstract
In this study an ultraviolet (UV) light processing was evaluated as a viable alternative for the microbiological stabilization of wines. Indeed, sulphur dioxide (SO2) is associated with health troubles in sensitive subjects, and the wine industry is looking for new innovative techniques that can help reducing SO2 levels in wines, without modifying their chemical and sensory properties. Industrial-scale trials were carried out by using the novel turbulent-flow reactor SurePure (Milnerton, South Africa) consisting of 40 UV lamps that emit at the germicidal wavelength of 253.7 nm (UV-C). Three wines, i.e. red (Montepulciano d’Abruzzo), rosé (Schiava), and white (Pinot gris) wines, were exposed to UV-C dosages ranging from 0 kJ/L (control) to 1 kJ/L, at a constant flow rate of 4000 L/h. All wines contained low SO2 levels. The effect of Sure Pure treatment on the microbial levels in the white and rosé wines was remarkable, since a 99.99% reduction of yeasts, acetic and lactic acid bacteria was achieved using UV-C dosages < 0.5 kJ/L. On the contrary, a dosage of 1 kJ/L resulted in an average log10 microbial reduction of 1-2 in Montepulciano wine. The level of reduction in microbial counts depended largely on UV-C dosage and absorptive properties of wine, being UV light more effective in treating white and rosé than red wines. Therefore, the reduction in microbial counts depended on both UV-C dosage and level of UV-absorbing compounds in wine. Preliminary tests on wines subjected to the higher UV-C dosage tested indicated no changes in the routine chemical analysis of wines (e.g. ethanol concentration, pH, volatile acidity, color intensity) in comparison with the controls. In addition, analysis of the aroma profile by gas chromatography and sensory evaluation tests did not find significant differences between UV-C irradiated (1 kJ/L) and control wines. In conclusion, the results indicated that a low dosage UV-C treatment holds considerable promise in winemaking for white and rosé wine, as an alternative technology to limit the use of SO2, without affecting smell and taste of wines.
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