The UV–vis spectroscopy has been used to determine the flavonoids both from the free and from the included essential oils in the prepared samples. The mint and lavender essential oils as such and those released from the matrices were analyzed in an organic solvent, dimethyl sulfoxide (DMSO) from Merck, respectively. The MS and LS powders were diluted with DMSO (at a concentration of 10 ppm), and with a mixture of DMSO-water 50% v/v. For the essential oils the absorption measurements were recorded using a Perkin Elmer, Lambda 35, UV–vis Spectrometer at a scan rate of 480 nm min− 1, with data interval of 1 nm.