Study On The Total Antioxidant Capacity And Bioactive Compounds Of Kiwi, Persimmon And Apple Fruits

Fruit is one of the major dietary sources of various antioxidant phyto-compounds for humans. Thus, it has been a focus to exploit and utilize the antioxidant bioactive compounds of fruits.The purpose of this study was to investigate the antioxidant potentials of eight different Actinidia genotypes, eleven different Diospyros genotypes and four different apple cultivars, and the relationships with the antioxidant bioactive compounds of the fruits.The antioxidant properties of the fruits extracts were evaluated for their potential antioxidant capacity by several assays (ABTS, DPPH, ORAC, FRAP, TBARS, HRSA, SRSA, MCC and HPA) and tested for their antioxidant bioactive compounds (total phenols, total flavonoids, total flavanols and vitamin C). Hopefully, the results will prove useful for the utilization of Actinidia and Diospyros in fruit.The main results were as follows:1. As expected, Diospyros and Actinidia fruit had much higher antioxidant capacity than apples. Antioxidant capacity of the three fruits decreased in the order: persimmon > kiwi > apple. The antioxidant capacity of persimmon was about 2-43-fold higher than that of kiwi, kiwi was 1-17-fold higher than that of apple. The antioxidant bioactive compounds contents showed a great variety among the different kinds of fruits and highly correlation with the total antioxidant capacity.2. In the Diospyros, the anxiodiant capacity of the wild D. lotus L species was 1-170-fold higher than that of other cultivars, and the astringent persimmon was higher than that of non-astringent persimmon. In the Actinidia,the anxiodiant capacity of wild A. latifolia species was 1-9-fold higher than that of other cultivars. The skin had the highest antioxidant activity in the whole kiwi fruit. In the different four apple cultivars,'Starking'had the higher anxiodiant capacity than that of others. And the antioxidant activity decreased during the growth development.3. Multiple reaction characteristics and mechanisms are likely involved, no single assay will accurately reflect all antioxidants in a mixed or complex system. Thus, to fully elucidate a full profile of antioxidant capacity, different antioxidant capacity assays may be needed to evaluate the antioxidant potential of natural sources of antioxidants. Among the methods used for quantifying antioxidant capacity, there were significant correlations among the four assays (ABTS, DPPH, ORAC and FRAP), while exhibited weaker correlations with other methods.4. A new method for simultaneously determination of 18 phenolic compounds by reverse phase high performance liquid chromatography(RP- HPLC)was studied. Chromatographic separation was performed by Zorbax SB-C18 chromatographic column(250 mm×4.6 mm ID, 3.5μm)using the mobile phase gradient elution of acetonitrile-acetic acid mixture at 30℃,flow rate at 0.6 mL/min and detection wavelength at 280nm.5. The contents of 17 phenolic compounds in Actinidia were determined that gallic acid, caffeic acid, chlorogenic acid, protocatechic acid, benzonic acid and catechin were the main phenolic compounds. The contents of 18 phenolic compounds in Diospyros were determined that gallic acid, chlorogenic acid, protocatechic acid, quercetin, and rutin were the main phenolic compounds.6. Correlation analysis was used to explore the relationships between phenolic compounds and antioxidant activity of Actinidia and Diospyros in fruit. For Actinidia, antioxidant activity was significantly correlated with gallic acid, ferulic acid, catechin, syringic acid, ellagic acid, sinapic acid and salicylic acid. For Diospyros, antioxidant activity was significantly correlated with catechin, rutin,phloridzin and quercetin.