Effects of different drying methods on phenolic contents, antioxidant, and tyrosinase inhibitory activity of peach blossoms

摘要

Fresh peach blossoms of two varieties were dried by using different methods, which include shade drying, freeze drying, microwave drying and hot air drying (at 30, 60, 90, 120 degrees C). The effects of different drying methods on phenolic contents, antioxidant and tyrosinase inhibitory activity were evaluated. Among the seven drying treatments, microwave drying yielded the highest contents of total phenolics, flavonoids, anthocyanins, proanthocyanidins and individual phenolic compounds in dried peach blossoms, while hot air drying at 30 degrees C gave the lowest retention of total phenolics, flavonoids, anthocyanins. As compared with shade drying and freeze drying, hot air drying at 60, 90, 120 degrees C resulted in higher retention of phenolic content. The highest antioxidant activity in dried peach blossoms was obtained by microwave drying, while hot air drying at 30 degrees C gave the lowest. The effect of different drying methods on antioxidant activity of dried peach blossoms was consistent with that of phenolic content. The highest tyrosinase inhibitory activity was achieved by hot air drying at 120 degrees C for variety yingchun' and 90 degrees C for variety huangjinmeili', but there was no significant difference among hot air drying at 60, 90, 120 degrees C for both varieties. The tyrosinase inhibitory activities of peach blossoms by microwave drying and freeze drying were comparable and much lower than that of shade drying. The results indicated that microwave drying was a desirable method for the preservation of phenolic compounds and antioxidant activity in peach blossoms, while shade drying and hot air drying at high temperature were favorable for tyrosinase inhibitory activity.