Ochratoxin A removal in synthetic and natural grape juices by selected oenological Saccharomyces strains.
OBJECTIVE
To assess, for the first time the efficiency in removing ochratoxin A (OTA) from laboratory medium [yeast peptone glucose (YPG)], synthetic grape juice medium (SGM) and natural grape juice by viable and dead (heat and acid-treated) oenological Saccharomyces strains (five S. cerevisiae and one S. bayanus) compared with a commercial yeast walls additive.


RESULTS
Levels of OTA during its interaction with six oenological Saccharomyces strains (five S. cerevisiae and one S. bayanus) or with a commercial yeast walls additive in YPG medium, in SGM or in natural grape juices was assessed by HPLC after appropriate extraction methods. A significant decrease of OTA levels in YPG medium and SGM was observed for many of the growing strains reaching a maximum of 45%, but no degradation products were detected. With both heat and acid pretreated yeasts, OTA removal was enhanced, indicating that adsorption, not catabolism, is the mechanism to reduce OTA concentrations. Adsorption was also improved when the yeast concentration was increased and when the pH of the medium was lower. Approximately 90% of OTA was bound rapidly within 5 min and up to 72 h of incubation with heat-treated cells of either S. cerevisiae or S. bayanus. A comparative study between heat-treated cells (HC) and commercial yeast walls (YW) (used as oenological additive), introduced at two different concentrations (0.2 and 6.7 g l(-1)) in an OTA-contaminated grape juice, showed the highest efficiency by HC to adsorb rapidly within 5 min the total amount of the mycotoxin.


CONCLUSIONS
Oenological S. cerevisiae and S. bayanus were able to remove ochatoxin A from synthetic and natural grape juices. This removal was rapid and improved by dead yeasts having more efficiency than commercial yeast walls.


CONCLUSIONS
The efficiency of heat-treated yeasts to remove OTA gives a new hope for grape juice and must decontamination avoiding negative impacts on human health.
Laboratoire du Génie Chimique UMR5503 (CNRS-INPT-UPS), Equipe: Génie des Systèmes Microbiens, Ecole Nationale Supèrieure Agronomique de Toulouse, Auzeville-Tolosane, Castanet-Tolosan, France.
H
H
Bejaoui
F
F
Mathieu
P
P
Taillandier
A
A
Lebrihi
D000327:Adsorption; D001628:Beverages / Q000032:analysis; D003470:Culture Media; D003666:Decontamination / Q000379:methods*; D005506:Food Contamination / Q000032:analysis*; D006801:Humans; D007218:Industrial Microbiology / Q000379:methods; D009793:Ochratoxins / Q000032:analysis*; D012440:Saccharomyces / Q000502:physiology*; D027843:Vitis / Q000737:chemistry*
D003470:Culture Media; D009793:Ochratoxins; C025589:ochratoxin A