Partial oxidation of the released hydrocarbons yields in a wide palette of other compounds : aldehydes ( e . g . formaldehyde, acrolein, and furfural ), ketones, alcohols ( often aromatic, e . g . phenol, guaiacol, syringol, catechol, and cresols ), carboxylic acids ( formic acid, acetic acid, etc . ).
32.
According to studies conducted in the 1990s by Greenpeace, the paper plant ( property of Celulosa S . A . ) is responsible for contaminating the Paran?River with chlorine-derived chemicals and others ( methoxyphenols such as chloro-guaiacol, di-and tri-chloro-phenols, alkylbenzenes, sulfur compounds, long-chain hydrocarbons, and chloroform ).
33.
The resulting intermediate is then oxidized again by a hydroxylase enzyme, likely monophenol hydroxylase again, at carbon 5, and methylated by COMT . The product, methylated at the two meta positions with respect to the alkyl substituent, experiences a final methylation at the 4 carbon by a guaiacol-O-methyltransferase, which also operates by a SAM-dependent mechanism.
34.
Another balancing flavor note unique to Hefeweizen beer is its phenolic character; its signature phenol is 4-vinyl guaiacol, a metabolite of ferulic acid, the result of fermentation by top-fermenting yeast appropriate for the style . " Hefeweizen "'s phenolic character has been described as " clove " and " medicinal " ( " Band-aid " ) but also smoky.
