ROLE OF CINNAMOYL ESTERASE-ACTIVITIES FROM ENZYME PREPARATIONS ON THE FORMATION OF VOLATILE PHENOLS DURING WINEMAKING

High levels of 4-vinylphenol and 4-vinylguaiacol were detected in wines made from grape juice initially treated with some enzyme preparations. Two enzyme activities, which operate successively, are responsible for this formation. First, the cinnamoyl esterase activity from enzyme preparation liberates cinnamic acids from their corresponding tartaric acid esters. Second, cinnamic acids are transformed into 4-vinylphenol and 4-vinylguaiacol by decarboxylase activity provided by the yeasts. This activity is quite stable throughout alcoholic fermentation. The high levels of volatile phenols in some enzymatically treated wines could be responsible for unpleasant phenolic off-flavors. During storage, these compounds decreased and corresponding ethoxyethylphenols increased.