Studies On Extraction, Isolation, Identification And Antioxidant Activity Of Sugarcane Polyphenol

China is the first country which planted sugar cane.Meantime,its sugarcane yield ranks the third worldwide. Sugarcane skin contains a lot of pigment which belongs to polyphenol compounds and flavonoid compounds, the content of polyphenols is much more than a lot of fruits and vegetables as well.Polyphenols extracted from sugarcane is of great significance to human nutrition, health,as well as disease control and prevention,since it has strong ability of clearing free radicals and antioxidant activity.At present,some researchers have studied phenols from cane tip and sucrose processing by-products,but few people do research on polyphenols in not edible part of the sugarcane,such as its skin and stalks.Sugarcane skin accounts for about20%of the quality.We apply response surface analysis method to study the sugarcane skin polyphenol ultrasonic extraction technology,which is based on the the single factor experiment.Compared the adsorption and desorption properties of various resin,we have found suitable separation methods and analyzed the polyphenol composition and content.Moreover,the antioxidant properties of sugarcane skin polyphenol have been evaluated.It is laid a theoretical foundation the on sugarcane skin natural pigment and its functional by an all-round way, the system of research.The main research conclusions are as follows:(1)Get the optimum process conditions of using ultrasonic method to extract sugarcane skin polyphenolThe experiment is designed to get the optimum technological extraction conditions of phenol in sugarcane skin by ultrasonic method. Based on the single factor experiments, the effect of solvent concentration, solid-liquid ratio, ultrasonic temperature and extraction time on phenol yield rate were studied respectively as well as their interaction by response surface analysis.The results demonstrated that the optimum conditions for extracting phenolic compounds from sugarcane skin were14-fold volume of53%aqueous ethanol solution, ultrasonic temperature of61℃and extraction time of31min.Under these optimum conditions,the yield rate of phenols was8.67%,which compared with the predicted value of8.83%according to the model, indicating that the prediction accuracy was98.19%.(2)Screen out the optimum resin and purification conditionsSix different resins have been selected to determine the adsorption and desorption ability for sugarcane polyphenols,and X-5resin is the optimization one. Isothermal adsorption experimental results under25℃,30℃and35℃show that X-5resin adsorb different capacity of cane polyphenols at different temperature,and the adsorption process conforms to the Langmuir isothermal adsorption model and Frenchlick isothermal adsorption model.What is more,the fitting effect is well.The adsorption is an exothermic process,which belongs to the preferential adsorption.The better result of applying X-5resin to purify sugarcane skin polyphenol was achieved that the mass concentration of column liquid was6.007mg/mL, adsorption velocity was2.0mL/min;desorption agent was the ethanol solution with mass concentration of70%, elution velocity was1.0mL/min,elution volume was120mL, adsorption analytic effect was well.Under the conditions above,sugarcane polyphenols has been greatly enriched.the content was increased from11.75mg/g to67.00mg/g, and the purity was increased from13.55%to77.28%.(3)Use HPLC to analyze the composition of polyphenols of the three samplesIt was showed by HPLC analysis that sample A, B and C all contained chlorogenic acid,ferulic acid and gallic acid.Ethyl acetate extraction and macro porous resin purification process have enriched sugarcane polyphenols at a certain degree,but it does not affect the composition of sugarcane polyphenols.The purity of three samples is A＜B＜C.The contents of chlorogenic acid, ferulic acid, gallic acid content in sample A are1.489mg/g,1.621mg/g and7.453mg/g;samples B are3.164mg/g,2.101mg/g and9.147mg/g; sample C are11.144mg/g,9.127mg/g and12.511mg/g.(4)Use two kinds of antioxidant system to evaluate the antioxidant ability of the three samplesThe total phenol content and purity of the three samples were11.75mg/g,13.55%;30.25mg/g,34.89%;67.0mg/g,77.28%. It can be seen from the experimental results that sugar cane polyphenols has a certain of oxidation resistance. At present, there are a lot of antioxidant function evaluation system. However, they just evaluate the multifunction of natural antioxidant in the food and biological system from one perspective. DPPH method and FRAP method all showed that with the increase of the polyphenols concentration, antioxidant ability was strengthened, but cane polyphenols antioxidant capacity was low than Vc.