Microbial stabilization of wines using innovative coiled UV-C reactor process: impact on chemical and organoleptic proprieties
Abstract
For several years, numerous studies aimed at limiting the use of SO2 in wines (thermal treatments, pulsed electric fields, microwaves …). Processes must be able to preserve the organoleptic qualities of wines with low energy consumption. In this context, ultraviolet radiations (UV-C), at 254 nm, are well known for their germicidal proprieties. In order to inactivate microorganisms in grape juice and wine without affecting the quality of the product, efficiency of UV-C treatment process should be optimized. Indeed, previous studies show a great efficiency for low absorbing liquids, but a poor one for high absorbing liquids, due to the lack of UV penetration. For this purpose, coiled tube UV-C reactor has been used in this study. The main component of this reactor is a FEP tube, helically wound around the UV lamp quartz sleeve. Dean vortices (radial flows) generated in this coiled tube reduce the UV dose (in J/L) required, ensuring a homogeneous dose distribution in absorbing liquids. UV-C dose was evaluated by actinometric measurments using iodide/iodate actinometry, allowing us to select the most suitable flow rate. The inactivation performance of this process on multiple strains (S.cerevisiae, D.bruxellensis diploid and triploid, and O.oeni) and the impact of UV-C treatment on sensorial, physicochemical proprieties and chemical compounds like thiols, were investigated on white and rosé wine. The entire continuous process has been evaluated in lab and semi-industrial scale at 2 hL/h. UV-C doses required to achieve a 6 log10 microbial reduction are low (less than 600J/L) in white and rosé wine. Sensorial and physicochemical analyses, after treatment and after three months, didn’t show differences between treated and untreated wines. Chemicals compounds quantification and sensorial analyses on red wine are currently in progress.
Issue: Macrowine 2016
Type: Poster
Authors
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