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Effect of chemical and biological adjuvants added during wine-making on OTA content

Several trials were performed with different adjuvants and with different amounts of each adjuvant. Five red wines with different content of OTA were used in trials with different fining agents: Atos, Micosorb, charcoal+kalium caseinate, Toxical. The results showed that products containing charcoal are efficient in decreasing the level of ochratoxin A in the wine and that when the concentration of OTA is high it isn t possible to achieve an acceptable level of OTA in the wine with any of the tested adsorbents.

The reduction obtained with Atos appears related to both the contamination level of wine and the amount of adsorbent used; for example the addition of 0.2 g/L produces a decrease of 55% in the content of OTA and the addition of 0.5 g/L adsorbent leads at least to a 90% reduction.

If OTA content is low, the amount of adjuvant to be used can be low: so the colour of red wine is not compromised. Otherwise, if the OTA content is high and a significant amount of charcoal must be used, the color intensity decreases significantly.

Other experiments tested also the possibility to reduce OTA content with fining corrective actions. Charcoal was the fining agent more able to reduce the OTA level. The effect of charcoal on OTA level seems to be good at high concentration considering short time (24 hours). In fact a reduction of 81% was proved. Considering longer time (2.5 days), the effect of high and low concentration of the fining agent resulted the same.

After 48 hours of contact PVPP and cellulose removed a similar quantity of OTA, but the amounts required for cellulose are lesser. Gluten and pea proteins have a similar behavior, but gluten is more effective at low amounts.

In order to evaluate reduction kinetics by yeast walls, 100 g/hL of them have been added to 5 aliquots of wine containing an OTA level of 0.54 ug/L. The maximum OTA reduction by means of yeasts and their by-products is generally of 8 days at 25°C, only Mycosorb permits a fast reduction (60 hours).

The amounts to have 40-50 % OTA decrease at 8 days of contact are about:
- 100 g/hL for yeast walls;
- 40 g/hL for yeast hulls;
- 200 g/hL for active dry yeast;
- 10 g/L for yeast crème.

High adsorbent action is produced at 25 g/hL by Mycosorb derived from S. cerevisiae.

Several bacterial strains were tested for their ability in reducing OTA content in musts and wine. Among the L. plantarum strains tested the most relevant activity was registered for strains belonging to the group V. The different Oenococcus oeni commercial strains tested showed different abilities in reducing OTA. In particular, R1 was the least efficient (16.1% reduction), while R4 allowed the best result (45.9% reduction) which is also similar to that obtained with L. plantarum V 22.

Informations connexes

Reported by

Università Cattolica del Sacro Cuore
Via Emilia Parmense 84
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