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