Degradation And Antioxidant Research Of Proanthocyanidins From Raspberry Seeds

Studies have shown that in addition to raspberry seed oil, the raspberry seeds also contain proanthocyanidins. It is a natural antioxidant which has strong anti-oxidation free radical scavenging ability, and variety of biological activities and pharmacological activities such as treatment of cardiovascular disease, anti-tumor, reduce cholesterol and so on. It has wide development prospects. Research at home and abroad have shown that the oligomeric proanthocyanidins had stronger physiological and pharmacological activities, so catalytic degradation for polymer proanthocyanidins has very vital significance. In this paper, the raspberry seeds were used as the research object and the proanthocyanidins fractionation, degradation and antioxygenation were analysed. The thesis mainly consists of four parts.We researched the hydrolysis of high polymers in the second part. The high polymers proanthocyanidins from the first part were used as hydrolysis of raw materials, with the average degree of polymerization and antioxidant activity as parameters, through the single factor and orthogonal experiment, finally determine the sulfurous acid dosage of16%, hydrolysis temperature is70℃, the hydrolysis time is40min. In this condition, the average degree of polymerization is2.6, the antioxidant activity is43%.The ultrasonic-assisted degradation extraction of proanthocyanidins from raspberry seeds was studied in the third part. The result of single factor and response surface methodology experiments revealed that the optimum extracted conditions were as follows:ethanol concentration of60%, material-to-liquid ratio of1:20(g:mL), ultrasonic power of200W, time of30min, ultrasonic temperature of40℃, formic acid dosage of15%, proanthocyanidins extraction yield was91.5%, the mDP of proanthocyanidins was1.96. Structural features of proanthocyanidins were confirmed by FTIR analysis.The antioxidant performance, scavenging activity of different extracts were studied in the fourth part. The results showed that:(1) The raspberry seed procyanthocyanidins has good antioxidant effect. The antioxygenic effects of0.04%proanthocyanidins is similar to these of0.02%TBHQ, the antioxygenic effect of proanthocyanidins was better than VE, proanthocyanidins with ascorbic acid (VC) or with citric acid exhibited remarkable antioxidant activity and synergistic effect, Vc was better than citric acid.(2) The abilities of scavenging hydroxyl radical of different degree of polymerization product were compared. The results showed that all the extracts had scavenging activities on hydroxy radical, but acted differently in different concentration range; And in a certain concentration range, the activity and concentration showed concentration-response relationship; On the whole, oligomers of proanthocyanidins has stronger hydroxyl radical scavenging ability, but the difference is not obvious, this may be related to the difference of proanthocyanidins in basic composition unit, molecular weight, space steric hindrance and other factors.