Effect of microoxygenation applied before and after malolactic fermentation on monomeric phenolics and tannin composition of Pinot Noir wine.

Autor: Yang, Y., Deed, R.C., Araujo, L.D., Waterhouse, A.L., Kilmartin, P.A.
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Zdroj: Australian Journal of Grape & Wine Research; Jan2022, Vol. 28 Issue 1, p95-106, 12p
Abstrakt: Background and Aims: This study examines the effect of microoxygenation (MOX) applied before and after malolactic fermentation (MLF) on monomeric phenolic compounds and the tannin composition of a young Pinot Noir wine. It provides a complementary study to an earlier report on the effect of MOX on Pinot Noir colour and pigment development. Methods and Results: Two oxygen doses [10.8 and 52.4 mg O2/(L · month)] were applied either before or after MLF for 30 days. The wines were analysed by a series of HPLC‐based methods for phenolic compounds, with sources including both the Pinot Noir grape and a minor contribution from commercial tannin and oak additives. Post‐MLF MOX led to the near complete hydrolysis of cis‐ and trans‐coutaric acids and to the conversion of trans‐caftaric acid to caffeic acid, which has been associated with MLF. An increase of syringic acid was also found with post‐MLF MOX. For tannin composition, MOX decreased the proportion of trihydroxylation (%Tri‐OH) but increased galloylation (%Galloyl). Between MOX treatments, the effect of MOX dosage was much stronger than MOX timing on phenolic measures. Conclusions: Post‐MLF MOX greatly affected the enzymatic hydrolysis of hydroxycinnamic acids. With MOX, the decrease in %Tri‐OH and the increase in %Galloyl could increase astringency perception. The higher oxygen dosage had a greater impact on tannin composition than shown previously with colour‐related parameters. Significance of the Study: The influence of MOX on Pinot Noir phenolic composition has not been reported previously in such detail. Applying MOX to a young Pinot Noir wine altered the phenolic units responsible for astringency. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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