Abstract:In order to ascertain the optimal vacuum freeze-drying technology of tea flowers and study the in vitro antioxidant activity of freeze-dried tea flowers，the flower of Fuding big white tea was taken as the research object，and the effects of different factors（pre-freezing temperature，pre-freezing time，vacuum degree，and maximum heating temperature of shelf）on the sensory score and rehydration ratio of the tea flower were examined. The optimal conditions were obtained through response surface optimization as follows：pre-freezing temperature of-30 ℃，pre-freezing time of 3.5 h，and maximum heating temperature of shelf of 39 ℃.Under these conditions，the sensory score of the freeze-dried flower of Fuding big white tea was 88.57±1.24，and the rehydration ratio was 3.26±0.14. The bioactive constituents and sensory indexes of the tea flower before and after freeze-drying were compared，and it was concluded that vacuum freeze-drying technology could better preserve the appearance and active constituents of the tea flower.Through research on the in vitro antioxidant activity of the freeze-dried tea flower，the result showed that the scavenging rate of hydroxyl radicals in the tea flower was significantly higher than VC at the same concentration，while the scavenging rate and reducing capacity of DPPH radicals were lower than that of VC at the same concentration.The IC50 for the scavenging rates of DPPH radicals and hydroxyl radicals in the freeze-dried tea flower were 78.85 μg/mL and 0.55 mg/mL，respectively，indicating that the tea flower had good antioxidant activity.