Abstract
The addition of formaldehyde or hexamethylenetetramine (HMTA) to grape musts marked by reduced phenolics in wines.
The formaldehyde selectively precipitated the nontannin flavonoid fraction and effectively slowed oxidative browning ("maderization") in white wines.
Similar detanninizing effects are obtained with the insoluble PVP. However, in this case the tannic flavonoid fraction is selectively eliminated, resulting in a decoloration of the wines and a lower stability to maderization.
The concentration of formaldehyde residues appears to be inversely related to the flavonoid content of wines. The excess of formaldehyde added to the must reacts with the sulfur dioxide, resulting in high residues of both formaldehyde and SO2 in the wines.
Therefore, for the maximum effectiveness of the treatment with the minimum concentration of residues, the addition of SO2 should be limited and the doses of formaldehyde should be established on the basis of the flavonoid determination.
- Accepted April 1971.
- Published online January 1971
- Copyright 1971 by the American Society for Enology and Viticulture
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