Abstract:

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 < 0.05), that is, k45 ℃ > 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.

Key words: carotenoids, kinetics, apparent activation energy, 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical, in vitrogastrointestinal digestion