Technologies for Extracting Anthocyanins from the Red Raspberry and their Free Radical Scavenging Ability

The aims of study was to find the best technology for extracting anthocyanins from the red respberry. Different technologies for the preliminary extraction of anthocyanins from red raspberry fruit as the raw material, including Ultrasound-Assisted Extraction (UAE) and Microwave-Assisted Extraction (MAE), were studied. The effects of extraction time, extraction temperature, solvent-material ratio and other factors on the anthocyanin yield were investigated. The center point combination experiment design was used to analyze the various extraction conditions, determine significance and interactions between various factors and optimize the extraction parameters. The final extraction rate obtained using MAE (0.0598 mg/g) was about 1.5-fold higher than that using UAE (0.0412 mg/g). The free radical scavenging activity of the extracts was examined in different in-vitro antioxidant experiments in comparison with ascorbic acid (Vc) as the control. In these DPPH (2,2-diphenyl-1-picrylhydrazyl), hydroxyl and ABTS (2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)) free radical scavenging experiments, MAE and UAE extracts showed free radical scavenging activities 2.8 and 1.5-fold, 4.7 and 3-fold and 1.2 and 1-fold higher, respectively, than those of the Vc control. Furthermore, the scavenging activities of red raspberry anthocyanin extracts against the different free radicals increased in the order hydroxyl > ABTS > DPPH, while the antioxidant capacity of the MAE extract was higher than that of the UAE extract.