Analysis And Antioxidant Activity Of Polyphenolic Composition Of Blood-flesh Peach

Peach fruit(Prunus perica(L.)Batsch) is rich in nutrient value and health benefits, because it isrich in polyphenols. In this paper, we investigated the changes of total phenolic content andflavonoid content in blood-fleshed peach ‘Tianxianhong’ as well as its corresponding antioxidantactivity at different ripeness stages, and compared with that in white-fleshed peach‘Jinhuadabaitao’ and yellow-fleshed peach ‘Jinxiang’. We also optimized the extractiontechnology of anthocyanins from blood-fleshed peach. These studies would provide experimentalbasis for further development and utilization of ‘Tianxianhong’ peach. The main results wereshown as follows:High performance liquid chromatography (HPLC) analysis showed that catechin andepicatechin were the main flavanols in skin and flesh of three peach cultivars.Results indicatedthat the catechin contents in the flesh and skin of three peach cultivars gradually reduced duringmaturity. The maximum content of catechin in the flesh of red, yellow and white flesh peach were33.2μg/g·Fw,82.8μg/g·Fw and25.2μg/g·Fw, respectively. And that in the skin were170.1μg/g·Fw,169.5μg/g·Fw and146.3μg/g·Fw, respectively. Catechin content was higher in the skin of the threepeach cultivars than in the flesh. The epicatechin contents are gradually increased in the flesh ofthe three peach cultivars during maturity. The maximum content of epicatechin in the flesh ofblood-flesh peach, yellow-flesh peach and white-flesh peach were35.8μg/g·Fw,29.5μg/g·Fw and4.8μg/g·Fw, respectively. On the contrary, the epicatechin contents gradually reduced in the skinof the three peach cultivars during maturity, and the maximum content of epicatechin in the skinof red, yellow and white flesh peach were29.3μg/g·Fw,17.3μg/g·Fw and4.0μg/g·Fw, respectively.Epicatechin content in red flesh peach in the early stages of fruit development was lower than thatin white flesh peach and yellow flesh peach, while in the later stages, it was higher than the othertwo. The maximum content of epicatechin in skin of three peach cultivars was higher than that inthe flesh.With yield of anthocyanins as index, based on single factor test, orthogonal test was adopted tooptimize extraction technology by taking ethanol concentration, pH of extract, type of acid,extraction time and solid-liquid ratio as factors. HPLC was used to determine the content ofanthocyanins with mobile phase of4%phosphoric acid-acetonitrile (85:15, pH=2.0) and detectionwavelength of520nm. The order of factors influencing yield of anthocyanins was pH of extract>solid-liquid ratio>ethanol concentration>extraction time. Optimum extraction technology was asfollowing: extracted3h with10times the amount of20%ethanol (pH=2.5) at40℃; Yield ofanthocyanins was up to55.8μg.g-1.The polyphenols and anyhocyanins extracts of three peach cultivars were investigated for theirantioxidant activity using1,6-Bis(diphenylphosphino hexane)(DPPH) and2,2-Azinobis(3-ehtylbenzothiazolin-6-sulfnicAcid)DiammoniumSalt,(ABTS)radical scavengingactivity capacity assay, oxygen radical absorbance capacity (ORAC) assay, and ferric reducingantioxidant power (FRAP) assay. Results showed that the antioxidant activity and totalpolyphenols content differed significantly among the three peach cultivars. A significantrelationship between antioxidant activity and polyphenols content was found, but no significantrelationship between antioxidant activity and anthocyanins content. It was found that red-shin and red-flesh possessed the more potent antioxidant activity in the most of the methods used exceptORAC, and thus red-fleshed peach could be a potential and rich source of natural antioxidant.