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.