Ochratoxin A removal during winemaking

Abstract

This work aims to investigate the performance of 20 strains of Saccharomyces sensu stricto to remove ochratoxin A (OTA) during vinification. Each strain was inoculated in triplicate in 10 mL of white must with a natural OTA content of 1.58 ng/mL, and again in the same must with the addition of OTA, to reach a total content of 7.63 ng of OTA/mL. This microvinification trial was performed at 25 °C for 90 days. The OTA content and the ethanol content of the wines were assayed; the OTA content of the lees was also analysed separately. The OTA content in wines produced from the naturally OTA-containing must varied from 0.143 to 0.950 ng of OTA/mL (mean 0.498 ng of OTA/mL). The OTA content in wines obtained from the must with the addition of OTA varied from 1.270 to 2.448 ng of OTA/mL (mean 1.661 ng of OTA/mL). The OTA content in lees varied from 1.537 to 7.456 ng of OTA/mg of biomass (wet weight). Interestingly, this last result indicates that OTA-removal from grape must was probably carried out by the yeast cell wall, acting like a sponge. A role of the parietal yeast mannoproteins in OTA adsorption during winemaking was hypothesised and the implications of these results in the winemaking of OTA-contaminated musts were discussed.