Optimization of Extraction Process and in Vitro Antioxidant Activity Analysis of Total Flavonoids from White-flesh Guava(Psidium guajava L. cv. Pearl)

The extraction process of total flavonoids from white-flesh guava was optimized and the in vitro antioxidant activity was studied. The leaves and peel of pearl guava(white meat)were used as raw materials. Based on a single factor experiment,the total flavonoids extraction quantity was used as an indicator to optimize the extraction process of total flavonoids from leaves and peel of guava by orthogonal test. On this basis,the total flavonoids in flesh of guava were extracted,and the in vitro antioxidant effects of total flavonoids in leaves,peel and flesh of guava were compared. The results showed that the optimal extraction process of total flavonoids from leaves and peel of guava were slightly different. The optimal extraction process of total flavonoids from guava leaves were as follows:ethanol concentration 50%,extraction temperature 65 ℃,solid-liquid ratio 1:20 (g/mL),extraction time 135 min. The optimum extraction process of total flavonoids from guava peel were as follows:ethanol concentration 60%,extraction temperature 45 ℃,solid-liquid ratio 1:7 (g/mL),extraction time 105 min. Under optimal conditions,the extraction quantities of total flavonoids in guava leaves and peel were(188.66±0.23)and(48.03±0.16) mg/g,respectively. Total flavonoids of guava leaves,peel and flesh showed good antioxidant activity in the experiments of ABTS radical and hydroxyl radical scavenging experiments,iron reducing force and total antioxidant capacity,among which total flavonoids of guava leaves had the strongest antioxidant capacity in vitro. This indicated that white-flesh guava flavonoids were expected to be a good natural antioxidant.