The quercetin-based glycosides were the major flavonol glycosides in both processed plum residues: from 57.30% (non-fermented) to 72.40% (fermented by A. niger) and 70.57% (fermented by R. oligosporus) (on the 9th day of SSF) of total flavonol glycosides of PP and from 86.50% (non-fermented) to 93.23% (A. niger – on the 9th day of SSF) and 94.63% (R. oligosporus – on the 14th day of SSF) of total fla- vonol glycosides of WPBP, while the remainders were isorhamnetin glycosides.