Thermal and oxidative stability of the Allium sativum L. bioactive compounds/α- and β-cyclodextrin nanoparticles

This paper presents the thermal and oxidative stability of the Allium sativum L. (garlic) bioactive compounds and the corresponding alpha- and beta-cyclodextrin nanoparticles. The complexation of the essential oil of A. sativum L. in beta-cyclodextrin was achieved by alcohol-water solution method, and nanoparticles were analyzed by thermogravimetry (TG), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). In order to obtain the type and the relative concentration of compounds encapsulated in cyclodextrins, the GC-MS analysis was used. The essential oil was analyzed by GC-MS before encapsulation and after successive extraction from the complex. The higher relative concentrations in the complex were obtained for diallyl-disulfide and diallyl-trisulfide. The nanoencapsulation yields were >60%, the higher ones being obtained for the case of beta-cyclodextrin. The biocompound/cyclodextrin ratio is important for the complexation yield, the best results being obtained for equimolar ratios, for all alcohols used. For the degradation of the raw samples in the presence of air and higher temperatures a decrease of the concentration of cyclic sulfide compounds was observed, compared with the case of nanoparticle degradation, where this tendency is not observed; although, the acyclic compounds were encapsulated in higher concentrations compared to the cyclic ones.