Reduction in copper and pesticide levels in grape musts: A new asset for the implementation of bioprotection in oenology.

Phytosanitary and copper treatments in viticulture are essential to protect vines against biotic and abiotic stresses. However, residues from these treatments can persist in grape musts and wines, potentially raising risks to consumer health. Those last years, investigations aimed at reducing those compounds received a growing interest. While viticultural and oenological approaches were initially explored to achieve this goal, microbial solutions have recently emerged. This study investigates the use of lactic acid bacteria Lactiplantibacillus plantarum - known for its production of bioactive extracellular substances - in both pure culture and co-culture with non-Saccharomyces yeasts, Torulaspora delbrueckii and Metschnikowia pulcherrima, recommended for grape must bioprotection conditions for the purpose of evaluating their potential ability to reduce copper and pesticide concentrations. Cultures were conducted in two media: a commercial grape juice standardized with copper and fluopicolide and a real grape must for 72 h. The copper quantification revealed that both non-Saccharomyces strains were effective to remove copper within 48 h, specially Metschnikowia pulcherrima managed to remove at least 80%. Regarding pesticides decrease, both yeast strains enabled up to 67% of the fluopicolide to be removed within 24 h. In conclusion, the results showed that M. pulcherrima could be of interest for pesticide and copper detoxification within 48 h without altering significantly the must composition. The combination of a L. plantarum strain, producer of bioactive extracellular components, with bioprotectant strains did not improve must detoxification.