Research On Extraction And Antioxidant Activity Of Tea Polyphenols By Ultrasonic-assisted ATPS

Tea Polyphenols are the general term of the polyhydroxyphenol in tea, have high resistance to oxidation and excellent natural antioxidant. For the extraction technology of polyphenol, traditional methods use ion precipitation and solvent extraction, which have some limitations, for example, the residual of metal ions and massive noxious solvents, low extraction rate and so on. The paper attempts to use the ultrasoundcombined aqueous two-phase extraction of Tea Polyphenols in Tea to reduce the extraction time and pollution, and to increase extraction yield. The paper established the ATPS(aqueous two-phase extraction) of ethanol and ammonium sulfate, discussed the ultrasonic and ATPS on the effects of the extraction and partitioning behavior of tea polyphenol, get the conditions of optimal extraction with the help of the response surface analysis experiment, finally, researched the antioxidation activity of tea polyphenol.The main results were summarized as follows:(1)Through the experiments we got the phase-formed concentration range upon 30? as following: Ethanol 8.04%~75.91%, water 23.49%~61.8%, ammonium sulfate 0.2%~37.87%. Upon 50? as following: Ethanol 6.8%~77.7%, water 20.9%~55.03%, ammonium sulfate 0.16%~41.4%. From the concentration range, the temperature cannot affect the aqueous two-phase system, but the temperature can reduce the time of Phase-separation.(2) The optimal extraction conditions by response surface design were found as follows: an aqueous two-phase system formed by adding 25%(W) of ammonium sulfate to 50%(W) aqueous ethanol, solvent-to-solid ratio of 70:1(mL/g), 16 min extraction and extraction temperature 45 ?. The yield of tea polyphenols in extracts under these conditions was 17.58%, the distribution coefficient was 18.3.(3) The effect on the capacity of tea polyphenol in vitro antioxidant compared with VE and VC. In the range of experimental concentration, he half clearance SC50 of tea polyphenol were327 ?g/mL?941.53 ?g/mL ?2011 ?g/mL on DPPH? radical, O2-? radical and ?OH scavenging activities, While the half clearance SC50 of VC were 26 ?g/mL?117 ?g/mL?745 ?g/mL, The half clearance SC50 of VE were 440 ?g/mL ?1500 ?g/mL ?1834 ?g/mL, therefore the DPPH? scavenging activities of VC was greater than tea polyphenol, and tea polyphenol was greater than VE. The O2-? radical of VC greater than tea polyphenol, and tea polyphenol was greater than VE. The ?OH radical of VC was greater than VE, and the VE was greater than tea polyphenol.(4) Through the different antioxidant activity was studied in rapeseed oil. Under the same 0.05% concentration, the tea polyphenols antioxidant activity was better than BHT and VE, which indicates that the polyphenols have good prospects for development in anti-oxidation, anti-corrosion additive industry in the future.