Kinetics of free radical scavenging activity of carotenoids and effect of in vitro simulated gastrointestinal digestion on their radical scavenging capacity

The 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity of carotenoids at different concentrations was determined as a function of temperature and changes in this activity after in vitro simulated digestion in artificial gastric juice, artificial intestinal juice and artificial gastrointestinal juice were investigated. The radical scavenging rate constant k was significantly negatively correlated with reaction temperature (P 45℃ > k37℃ > k30℃. The radical scavenging capacity α was not significantly influenced by reaction temperature, but it was significantly positively correlated with initial carotenoids concentration, which did not significantly affect k value. The scavenging reaction was fitted to a first-order reaction kinetics. EC50, k and half-life t1/2 were significantly influenced by reaction temperature and higher temperature resulted in reduced EC50 and t1/2, and increased k. The apparent activation energy Ea and the constant K0 were not influenced by the initial concentration of carotenoids, which were 17.039 kJ/mol and 7.38 × 106, respectively. The radical scavenging capacity of carotenoids was decreased after in vitro gastrointestinal digestion. Moreover, the radical scavenging capacity of carotenoids mixed with oil was lower than that with no oil added, suggesting that fat-soluble carotenoids are more easily digested in oil. The digestion and absorption of carotenoids were significantly influenced by different types of oil containing different fatty acid compositions. © 2016, China Food Publishing Company. All right reserved.