Foul smell - The right enzyme choice, a tool to avoid volatile phenol production

A Technical Guide
for Wine Producers

RECENT ARTICLES | WYNBOER HOME

Foul smell - The right enzyme choice, a tool to avoid volatile phenol production

Céline Fauveau, Céline Bajard-Sparrow and Patrice Pellerin - DSM Food Specialties
The adverse effects of ethyl and vinyl phenols on the organoleptic qualities of wine are well known. Volatile phenols are produced during fermentation and/or wine ageing by successive enzyme reactions:

The concentration of hydroxy-cinnamic and phenolic acids found in must in the form of esters with tartaric acid is significantly increased by the use of enzyme products with high cinnamyl esterase activity.
During fermentation, hydroxy-cinnamic acids are transformed into vinyl-phenols by cinnamate decarboxylase. This enzyme is produced by some Saccharomyces cerevisiae strains known as POF(+) (Phenyl Off Flavors (+)) as well as by contaminating yeast.
In red wine, Brettanomyces contamination leads to transforming vinyl-phenols into ethylphenols through the vinyl-phenol reductase action. In white wines, due to lower pH and higher SO2 content Brettanomyces is unlikely to develop.

Analysis shows that the level of cinnamyl-esterase activity in DSM enzymes is naturally lower than that of purified or so called FCE enzymes, without the need to undergo a post-production purification process. Using DSM enzymes in vinification limits the formation of volatile phenols maintaining their concentration under the threshold.

Cinnamyl esterase activity of commercial enzyme preparations for maceration and extraction.

NFCE ENZYMES IN WHITE WINE MAKING
In white and rosé wine, vinyl phenols cause unwanted odors reminiscent of poster paint and carnation. In low concentrations these compounds spoil the aromatic subtlety of a wine.
The incidence of these components produced during fermentation is dependent on several enzyme reactions and can be avoided by using POF(-) strains that have no cinnamate decarboxylase activity, i e strains such as Fermicru© LS2, Fermicru© AR2, Anchor© Vin 13, Anchor© NT116.
Since the required enzyme is not available, the transformation of hydroxycinamic acid to vinyl phenols cannot occur. However, restricting the yeast choice to POF(-) strains limits vinification alternatives since some POF(+) strains give very interesting vinification results.
By using DSM enzymes with a naturally low level of cinnamyl esterase activity (NFCE) the formation of phenol acids is kept to a minimum. Since the first of the two enzyme reactions is prevented from taking place, the vinyl phenol concentration in the wine remains negligible and is always below the perception threshold.

NFCE ENZYMES IN RED WINE MAKING
In red wine making, the use of a POF (+) strain of Saccharomyces cerevisiae is of no significance as the 4-vinyl phenol and 4-vinyl gayacol product of hydroxycinamic acid transformation combines with tannins.
However, Brettanomyces type contaminating yeast has enzymes capable of forming substantial quantities of ethyl phenols (4-ethyl-phenol and 4-ethyl gayacol).
These quantities are sufficient to cause odors reminiscent of horse sweat and stables. This defect, known as "phenolic odors", becomes fully perceptible from about 600 µg per literand is particularly dominant in higher concen-trations. (Chatonnet et al., 1997, 1990, 1992).
DSM ENZYMES ARE NATURALLY FCE
DSM has an in-depth knowledge of the fermentation processes occurring under production conditions.
By using Aspergillus niger strains specifically selected for oenological purposes, DSM enzyme preparations are formulated to naturally maintain any unwanted effects to a negligible level.

The graph illustrates that where there is no Brettanomyces contamination, no ethyl phenol production occurs, even if the enzyme used has a high cinamyl esterase activity. (See the development of Brettanomyces in red wines) the use of an NFCE enzyme preparation such as Rapidase© Ex Color, avoids unwanted odors resulting from a Brettanomyces contamination.

Vinyl-phénols content in wines obtained from grape must clarified with pectic enzymes (appart from the control) and fermented with a POF (+) yeast strain.
Wynboer is incorporated in WineLand, magazine of the SA wine producers.
Subscribe to WineLand

Visit our sister sites:

South African wine farmers' representative organisation

Facts, figures, contact details and much more in the 2009/10 Directory