The present invention relates to a method for modifying polyphenol containing plantmaterial(s), wherein said method comprises: mixing at least one polyphenol containingmaterial and at least one solvent to provide a mixture； heating the mixture toeliminate bacterial species present to provide a heated mixture； adding at leastone polyphenol modifying strain of lactic acid bacteria and optionally at leastone protein source, in optional order or simultaneously, to the heated mixtureto provide a fermentation mixture； and subjecting the fermentation mixtureto conditions suitable for fermentation of the fermentation mixture to providea mixture of modified polyphenol containing plant material(s)； and optionallyeliminating the polyphenol modifying strain of lactic acid bacteria to providea mixture of modified polyphenol containing plant material(s) free from livinglactic acid bacteria.
