Extraction And Identification Of Polyphenols From Kiwifruit Pomace

In order to improve the comprehensive utilization value of kiwifruit pomace,Qinmei and Hayward pomace of cutting from the dried fruit and can as raw materials,ultrasonic assisted method,Box-Behnken response surface design was used to optimize the extraction process conditions of two kinds of polyphenols of pomace.The static adsorption rate and desorption rate of 7 kinds of macroporous adsorption resin purification effect of polyphenols were compared to determine the purification conditions of polyphenols.Polyphenols of pomace composition were identified preliminary analysis by the HPLC method,the antioxidant capacity of polyphenols from pomace was evaluated by a variety of antioxidant systems in vitro,which laid a foundation for the utilization of polyphenols from kiwifruit pomace.The main conclusions are as follows:?1?Ultrasonic assisted ethanol method was used to extract polyphenols of pomace of Qinmei and Hayward,on the basis of single factor test,the response surface methodology was used to analysis,the quadratic regression model was established.The optimum extraction conditions of polyphenols of Qinmei kiwifruit pomace were: The ethanol concentration was 53 %?V/V?,the ultrasonic temperature was 60 °C,the ratio of liquid-solid was 35:1?mL/g?,the ultrasonic time was 60 min,the extraction yield of polyphenols was 23.98 mg/g,the prediction value was 24.30 mg/g,the actual value reached the predictive value of 98.68%.The optimum extraction conditions of polyphenols from Hayward pomace were as follows: the concentration of ethanol was 65 %?V/V?,the ultrasonic temperature was 65 °C,the ratio of liquid-solid was 35:1?mL/g?,the ultrasonic time was 60 min,the extraction yield of polyphenols was 18.83 mg/g,the predicted value was 19.51 mg/g,and the actual value was up to the predictive value of 96.51 %.?2?The effect of seven kinds of resins on the purification of polyphenols from kiwifriuit pomace was different,the purification effect of polyphenols of Qinmei pomace with D101 is good,the optimal conditions were: Polyphenols concentration was 6 mg/mL,sample volume was 380 mL,sample flow rate was 1 mL/min,elution concentration was 70 %?V/V?,the amount of eluent was 145 mL,elution flow rate was 1 mL/min,after purification,the purity of polyphenols of Qinmei pomace was 70.10 %.The purification effect of polyphenols of Hayward pomace with HPD400 is good,the optimal conditions were: Polyphenols concentration was 3 mg/mL,sample volume was 300 mL,sample flow rate was 1 mL/min,elution concentration was 70 %?V/V?,the amount of eluent was 120 mL,elution flow rate was 1 mL/min,after purification,the purity was 71.79 %.?3?There were differences in the contents and types of the phenols in the pomace of Qinmei and Hayward.There were 9 kinds of single phenolic compounds in the Qinmei pomace,content from high to low were: Epicatechin,protocatechuic acid,myricetin,chlorogenic acid,quercetin,gallic acid,p-coumaric acid,ferulic acid and phloridzin.There were 8 kinds of single phenolic compounds in the Hayward pomace,content from high to low were: Quercetin,myricetin,epicatechin,protocatechuic acid,chlorogenic acid,p-coumaric acid,ferulic acid and phloridzin.The higher content of phenols in Qinmei pomace were epicatechin and protocatechuic acid,accounted for 81.11 % of the total phenolic compounds,and the higher content of phenols in Hayward pomace were quercetin and myricetin,accounted for 74.05 % of the total phenolic compounds.In addition to quercetin and myricetin,the content of phenolic compounds in Qinmei pomace were higher than that of Hayward pomace,and the total phenolic content was higher than that of Hayward pomace.?4?The antioxidant activity in vitro of crude extracts and purified of polyphenols of Qinmei and Hayward pomace showed that polyphenols of kiwifruit pomace had certain capacity of scavenging free radicals,reducing Cu²⁺,Fe³⁺ and total antioxidant capacity,which Qinmei purified polyphenols of pomace had the strongest ability of scavenging DPPH·free radical,the IC50 value of scavenging DPPH·free radical was 5.82 ?g/mL,but weaker than the positive control VC.Trolox equivalent of scavenging ABTS+· free radicals was 249.40 mmol/g.·OH scavenging rate increases with the increase of polyphenols concentration,but lower than that of VC,purified polyphenols of Qinmei pomace had the most high reduction ability of Cu²⁺,Fe³⁺ and total antioxidant capacity,followed by purified polyphenols of Hayward pomace,crude extracts of Qinmei pomace,crude extracts of Hayward pomace.