Extraction, Seperation And Antioxidant Activities Of Phenolic Compounds In Logan Seed

Longan seed accounts for 17%of longan fruit,which is discarded during fruit processing or freshly consumed.In order to use this kind of by-product,the main nutrients and functional ingredients in longan seed were analyzed,and the phenolic compounds in the seed were seperated and purified to test their antioxidant activities.The main results were as follows:1.The contents of protein,fat and free amino acids in longan seed were 7.01±0.38%, 2.62±0.20%and 0.63±0.01mg/g respectively.It was shown that the content of these compounds were higher than that in lichi seed and there were many kinds of fatty acids and free amino acids in longan seed.2.Phenolic compounds in the ground longan seed were extracted with 50%ethanol(1:10,w/v) for 3 hour at 70℃and yielded 48.26±1.88mg/g(on the basis of galic acid).3.Ethanol in the phenolic extracts was removed by rotary vacuum evaporator at 60℃and the concentrates were uploaded onto an AB-8 macroporous resin column at 1 ml/min.The adsorbed phenolic compounds were eluted by 60%ethanol at 1 ml/min.The eluents were collected and the phenolic compounds in the collects were analyzed using HPLC.The results showed that there are at least 9 kinds of phenolic compounds in longan seed according to HPLC peaks and the HPLC peaks greatly differed in different concentration ethanol collects,indicating that AB-8 macroporous resin could be used to separate and purify phenolic compounds in longan seed.4.The in vitro antioxidative test indicated that the extacts of longan seed had better scavenging capacity for DPPH and hydroxyl free radical and higher reducing power than Vc.Moreover, thery showed scavenging activity for superoxide free radical.However,their capacity for reducing oxidation speed of oil was lower than tea polyphenols.