The effect of filtration on red wine

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The aim of this study was to explore the impact of commercial scale filtration on wine macromolecules, colloids and sensory profile.

Project layout
       Samples from commercial Shiraz and Cabernet Sauvignon wines from two bottling lines were collected before and after cross-flow filtration, before and after lenticular filtration, after 0.65 µm and 0.45 µm membranes.
       Impact of membrane type was also assessed in one wine.
       Wines were analysed at bottling and after nine and 18 months.

Results
       No significant impact on tannin concentration, composition or colour probably as a result of the fact that these commercial filter membranes are not new and high tannin and colour cultivars were used;
       Cross-flow and lenticular filtration had a minor effect on polysaccharides. 0.45 µm had the greatest effect;
       Cross-flow filtration reduced average particle size the most;
       After 18 months of bottling ageing the average particle size of filtered and unfiltered wines were the same for the older wines;
       Average particle size was substantially smaller in the filtered younger wines than the unfiltered young wines.
       Inconsistent results were obtained in terms of sensory analysis – some wines showed improved overall fruit aroma and some a decreased overall fruit aroma. It was concluded that the effect of filtration on wine sensory attributes was minimal.

Significance of the study
Commercial filtration is done to protect wines against microbial spoilage. It is often believed that filtration can “damage” wines in terms of quality and appearance and some producers therefore take the risk of possibly getting after bottling microbial spoilage by bottling their wines “unfiltered.” This particular research proves otherwise, especially in the case of bottling older wines.



Reference
McRae, J.M., Mierczynska-Vasilev, A., Soden, A., Barker, A.M., Day, M.P. and P.A. Smith (2017). Effect of commercial-scale filtration on sensory and colloidal properties of red wines over 18 months bottle aging. Am J Enol Vitic. 68:263-274; DOI: 10.5344/ajev.2017.16095

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