Abstract:

Fresh daylily flowers were processed into powder by the following procedures of blanching, drying and comminution, and the powder was extracted with different solvents. The suppression effects of daylily flower extracts on nitrosation were evaluated in terms of the nitrite scavenging activity and nitrosamine synthesis inhibiting activity determined by spectrophotometric method. The 70% methanol extract of daylily flower obtained by the water bath extraction for 0.5 h in an ultrasonic filed had high nitrite scavenging activity and nitrosamine synthesis inhibiting activity, reaching 66.9% and 54.7%, respectively. The nitrite scavenging activity and nitrosamine synthesis inhibiting activity of daylily flower varied slightly during fridge storage. Among four cultivars (Mengzihua, Baihua, Xiye and Daogan) of daylily flowers, Daogan had the highest nitrite scavenging activity and nitrosamine synthesis inhibiting activity and Xiye the lowest. Stream blanching treatment could maintain higher nitrosamine synthesis inhibiting activity than boiling water blanching treatment, although daylily flowers treated by them both had lower nitrosamine synthesis inhibiting activity than unblanched ones. A highest nitrosamine synthesis inhibiting activity was found in freeze-dried daylily flowers in comparison with sunlight-dried ones followed by hot air-dried ones. In general daylily flowers possess some nitrosamine synthesis inhibiting activity which is affected by cultivars and blanching, drying and cool storage treatments.

Key words: daylily flower, nitrosamine synthesis inhibiting activity, drying methods, blanching methods, cool storage, cultivars