In order to investigate the decrease in the residual SO
2 amount following the opening bottles, six wine vinegars produced in Europe were tested.
1. The highest amount of acetaldehyde was detected in sherry vinegar, then in balsamic vinegar, white wine vinegar, and red wine vinegar in that order.
2. Tartaric acid accounted for some 50% of the total non-volatile organic acids in the wine vinegars. Pyruvic acid was detected at concentrations of 10-25 μg/g in four samples, and in trace amounts in the remaining two samples. No α-keto glutaric acid was detected.
3. Most of the SO
2 in the wine vinegars was of the bound type. Little or only a trace amount of free SO
2 was detected.
4. The amounts of SO
2 in both the bound and free types were higher in wine than in wine vinegar.
5. The total amount of residual SO
2 in the wine vinegar decreased following the opening of the bottles in a similar pattern for five samples, while a rapid decrease was observed in one sample of red wine vinegar.
6. The total SO
2 amounts decreased faster in the wine vinegars than in the wine. It was suggested that the decrease depended on the type and amount of wine vinegar components that could be bound to SO
2, as well as that the low pH value could be a factor.
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