Study Of Separation,Purification,and Antioxidant Activity Of Polyphenols From Blueberry Pomace

In the present study, the extraction technology of blueberry pomace polyphenols was optimized by response surface method; the purification parameters of blueberry pomace polyphenols by macroporous adsorption resins was studied in order to improve the purity of blueberry pomace polyphenols; polyamide chromatography was used in the preliminary separation of blueberry pomace polyphenols and HPLC-DAD-ESI-MS tandem was used in the analysis of the composition of blueberry pomace polyphenols; the antioxidant activity of crude extract and fractions of blueberry pomace polyphenols were evaluated in vitro. The results were as follows:Single-factor experiment was used to study the effects of ethanol concentration, liquid-solid ratio, extraction time, extraction temperature, oscillation frequency, pH, and times of extraction on the extraction rate of blueberry pomace polyphenols. The results of single factor experiment on extraction conditions were optimized by Plackett Burman Design and response surface method. The best extraction conditions were as follows:ethanol concentrate 60%, liquid-solid ratio 20:1, extraction temperature 80℃, pH 2. Under those conditions, the extraction yield of blueberry pomace polyphenols was 97.01%.The static adsorption and desorption of eight types of macroporous resin showed that the absorption capacity and desorption rate of AB-8 resin were 28.48mg/g and 95.49%, respectively. In addition, the time for AB-8 resin to reach adsorption and desorption equilibrium was short, so it was most suitable to purify blueberry pomace polyphenols. The optimum absorption parameters for AB-8 resin were as follows: polyphenols concentration 2.6 mg/mL, pH 2, feeding rate 2.0 mL/min and the the optimal desorption parameters were ethanol concentration 60%, elution rate 2.0 mL/min, elution volume 80mL. After purification, the purity of polyphenols was increased from 11.05% to 59.29%.Blueberry pomace polyphenols was separated by polyamide chromatography preliminary and polyphenols composition of each fraction was indentified according to HPLC-DAD-ESI-MS tandem analysis and related referenceses. The result showed that there were sixtheen kinds of polyphenols in blueberry pomace: Delphindin-3-galactoside, B-type procyanidin dimmers, delphindin-3-glucoside, delphindin-3-arabinoside, Cyanidin-3-galactioside, Petunidin-3-galactoside, Petunidin-3-glucoside, Petunidin-3-arabinoside, A-type procyanidin dimmers, Malvidin-3-galactoside, Malvidin-3-glucoside, rutin, Quercetin 3-O-gluconide, quercetin and two unknown polyphenols.Seven kinds of methods were used to evaluate the antioxidant activity of Blueberry Pomace Extraction Polyphenols (BPEP), Blueberry Pomace Purification Polyphenols (BPPP) and Rutin. The ABTS free radical scavenging activity, DPPH free radical scavenging acticity, nitrite scavenging activity, ORAC value of BPPP and BPEP were higher than or equal with that of Rutin. However, the order of reducing power and FRAP value were BPPP> Rutin> BPEP, and the order of ·OH free radical activity scavenging activity and superoxide Radicals scavenging activity of rutin were higher than BPPP and BPEP.