Abstract:This study aimed to select the optimal drying method for preparing celery ultrafine powder. Celery leaves and petioles were adopted as experimental materials，and the influences of different drying treatments on the physicochemical properties and antioxidant capacity of celery leaf and petiole ultrafine powder were investigated. Three drying approaches，including vacuum freeze-drying，hot air drying and air fryer drying，were separately applied to dehydrate celery leaves and petioles. The results revealed that significant differences existed in physical indicators （solubility，water holding capacity，bulk density），chlorophyll content and antioxidant activity among ultrafine powders processed by the three drying methods. The celery ultrafine powder produced by air fryer drying possessed the maximum bulk density （0.87 g/mL） and water holding capacity （7.17%）.Samples treated with vacuum freeze-drying obtained the highest chlorophyll content and solubility，and the values of freeze-dried leaves were higher than those of freeze-dried petioles. Vacuum freeze-dried celery ultrafine powder showed the strongest antioxidant capacity：the DPPH radical scavenging rates of leaf and petiole samples reached 67.00% and 86.67%，respectively，while their total reducing powers were 88.03 mg/g and 92.88 mg/g correspondingly. In summary，vacuum freeze-dried celery ultrafine powder exhibited better comprehensive physicochemical properties and stronger antioxidant capacity compared with samples prepared by hot air drying and air fryer drying.