AWRI Webinar: Post bottling effects of early oxygen exposure during red winemaking
Date(s) - 12 Nov 2013
11:30 AM - 12:30 PM
Reductive aromas often develop when wine is made in closed tanks, and given almost equal proportions of reductive wine faults are found globally under cork as well as screwcaps this indicates that closure may not be solely to blame. Much anecdotal evidence points to early oxygen addition during fermentation to be beneficial. In our recent trial, Shiraz wines were made in vinimatics with several gas treatments. Evolution of hydrogen sulfide was considerably reduced early during fermentation with both 40% and 20% oxygen treatments, whereas no decrease was observed in nitrogen-sparged and control ferments. The continued absence of some volatile sulfur compounds after 12 months in oxygen-treated wines would point to the benefits of these treatments. The oxygen-treated wines had significantly lower concentrations of metals, tannins and total free anthocyanins but higher non-bleachable colour. Oxygen also brought about changes in the tannin structural composition commensurate with 1-2 years of ageing. The belief that splashing involved in cellar operations may just be physically displacing H2S has been disproved given little difference is observed between the control and nitrogen treatments.
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