Wspólnotowy Serwis Informacyjny Badan i Rozwoju - CORDIS

Effect of wine-making on OTA content

The winemaking process causes an OTA decrease. The stage that causes the most important reduction is the malo-lactic fermentation. In wines that aren t intended to the malo-lactic fermentation, the OTA level can be reduced by means of corrective actions with charcoal-base adjuvants. If wines have a slight OTA contamination, charcoal-base adjuvants can be used on the end-product in concentrations of 10 g/hL maximum, to reduce the OTA concentration without reducing the wine colour. If wines have an important OTA contamination, charcoal-based adjuvants can be used on the must before maceration, so it is possible to use concentrations of the product higher than 10 g/hL, able to reduce the OTA concentration without reducing wine quality, wine colour in particular. When ochratoxin A contamination occurs in grapes, some practices may be implemented to reduce its carry-over to wine. In all cases, it is recommended to determine the ochratoxin A content in must.

In the case of significant OTA contamination the following procedures should be evaluated:
- Avoid or reduce skin maceration;
- Adapt pressing rate to the health status of grapes (reduce time of operation)
- In case of red grapes, treat must before fermentation (be aware of possible losses in aromatic and polyphenolic compounds)
- Avoid the use of pectolytic enzymes to aid clarification, filtration or centrifugation are preferable
- Use fining agents known to be effective againts OTA (be aware of regulation 1622/2000, laying down rules for the use of fining agents in white and red vinification)
- Use yeast and bacteria known to be effective againts OTA (either by its adsorption or transformation)

Operations unit such as solid-liquid separation and the fermentative processes are effective in reducing OTA. In order to manage the hazards of OTA in winemaking and to verify if OTA content in wine is lower than the legal limit of 2 µg/L defined by European Commission (EC regulation N° 123/2005 of 26 January 2005), OTA analysis in must and in wine at the end of alcoholic fermentation would be enough, since the following phases reduce OTA content.

Reported by

UNIVERSIDADE DO MINHO
Largo do Paço Campus de Gualtar
4710-057 BRAGA
Portugal
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