Characterization of carvacrol beta-cyclodextrin inclusion complexes as delivery systems for antibacterial and antioxidant applications

Carvacrol is a good natural antimicrobial and antioxidant agent; however, its poor aqueous solubility and high volatility limit its application in food systems. Beta-cyclodextrin (ΒCD) is able to encapsulate hydrophobic molecules improving its aqueous solubility and reducing its volatility. ΒCD-carvacrol inclusion complexes were prepared using kneading (KN) and freeze drying (FD) methods. Sizes of ΒCD-carvacrol complexes were 441 ± 12 nm and 899 ± 44 nm and entrapment efficiencies were 83.79 ± 2.89% and 91.31 ± 0.41% for KN and FD BCD-carvacrol complexes, respectively. Polydispersity index was higher (P < 0.05) than 0.1 for both methods, indicating a polydisperse system. Differential thermograms and phase solubility study indicated formation of 1:1 stoichiometry inclusion complex. Trolox Equivalent Antioxidant Capacity (TEAC) values ranged from 7491 to 6421 μmol TE/g among treatments, where KN ΒCD-carvacrol complex showed the lowest (P < 0.05) antioxidant activity. Storage stability of ΒCD-carvacrol complexes proved beneficial to carvacrol encapsulation. Antimicrobial activity against Escherichia coli K12 and Salmonella enterica serovar Typhimurium LT2 showed that all BCD-carvacrol complexes inhibited bacterial growth at lower (P < 0.05) carvacrol concentrations (values ranged from 300 to 350 μg/mL) compared to free carvacrol (≥1000 μg/mL). Results indicate that these ΒCD-carvacrol complexes could have important applications in food systems due to their storage stability and improved antimicrobial activity.