Study on extraction of polyphenols of red pine bark and their antioxidant activity

The extraction of polyphenols compounds of red pine bark using enzymatic hydrolysis pretreatment combined with ethanol immersion extraction was researched. And antioxidant activity of polyphenols was also studied. Yield of polyphenols and hydroxyl free radical scavenging rate as indicators, on the basis of single factor experiment, technological parameters of extracting polyphenols were determined by response surface method to optimize extraction process conditions as following:enzyme additive amount 116.70U/g, enzymatic hydrolysis time 2.60h, enzymatic hydrolysis temperature 53.00℃, ethanol additive amount 49.30%. Under the condition of the extraction process, yield of polyphenols and hydroxyl free radical scavenging rate were 11.84%and 76.91% respectively. Electron spin resonance (ESR) assay was employed to evaluate the antioxidant activity of polyphenols. Hydroxyl free radical scavenging rate of polyphenols improved with the increase of adding polyphenols concentration, which indicated high concentrations of polyphenols could enhance their antioxidant activity.