Physicochemical properties, antioxidant action and practical application in fresh cheese of the solid inclusion compound γ-cyclodextrin·quercetin, in comparison with β-cyclodextrin·quercetin

Abstract

Quercetin is an antioxidant flavonol very sensible to light and oxidants that can benefit from stabilisation by encapsulation into cyclodextrins. In this work we study the solid inclusion compounds of quercetin with β- and γ-cyclodextrins (β-CD and γ-CD) obtained by freeze-drying. Combined results from microanalysis, FT-IR, powder X-ray diffraction, 13C{1H} CP/MAS NMR spectroscopy and thermogravimetry demonstrating that γ-CD, having a larger cavity, is the most adequate host to form a stable inclusion complex with quercetin. The anti-peroxidation capacity of the compounds was determined and followed the order β-CD·quercetin≫quercetin>γ-CD·quercetin. Both γ-CD·quercetin and β-CD·quercetin are able to inhibit DPPH radicals at a rate three times faster than pure quercetin, but their EC50 is higher (50μMvs 17μM for quercetin). The practical applicability of the two CD·quercetin adducts as nutraceutical additives in fresh cheese was established. Fortified fresh cheese had a firmer texture and yellowish colour, but no significant changes in the overall sensorial qualities were found by a panel of non-trained tasters when compared with the control (non-treated fresh cheese).