Abstract: In this study, hydroxyl and DPPH free radical scavenging assays were used to investigate the antioxidant capacity of novel inclusion complexes of hexahydro-β-acid, a hydrogenated derivative of resin in hops, with α, β and γ-cyclodextrin as well as 2-methyl, 2,6-bimethyl and 2,3,6-trimethyl-β-cyclodextrin. The results suggested that all inclusion complexes had antioxidant activity in varying degrees and their scavenging capacity against hydroxyl and DPPH free radicals was better than that of hexahydro-β-acid at the same concentration. On the basis of the above results, the synergistic antioxidant activity was evaluated on four inclusion complexes (2-methyl-β-cyclodextrin, hydroxypropyl-β-cyclodextrin, 2,3,6-trimethyl- β-cyclodextrin and γ-cyclodextrin), mixed with food additives (vitamin C, sodium chloride, citric acid and sucrose) in comparison with sodium benzoate. The results showed that all binary mixtures of inclusion complexes with citric acid and quaternary mixtures with vitamin C, NaCl and sucrose had no synergistic antioxidant activity in hydroxyl radical system, but the binary combinations of inclusion complexes with vitamin C, sodium chloride or sucrose were synergistic. Meanwhile, all binary/quaternary combinations except binary combination with sucrose had good synergistic antioxidant activity in DPPH free radical scavenging assay. However, sodium benzoate had no synergism with all four food additives in binary combinations.

Key words: hexahydro-β-acids, cyclodextrin inclusion complex, sodium benzoate, food additives, synergistic antioxidant activity