Optimization of Extraction Technology and Antioxidative Activity of Ellagic Acid in Raspberry by Response Surface Methodology

The aim of this study was to determine the optimal extraction process of raspberry ellagic acid by microwave-assisted extraction and study its antioxidant activity. Red raspberry was used as experimental material,ethanol extraction solvent was used,and ellagic acid was extracted from red raspberry by microwave-assisted solvent method. The extraction process of ellagic acid in red raspberry was optimized by single factor test and response surface test. The ellagic acid was analyzed by chromatography (HPLC) and its oxidation resistance was investigated. The results showed that the optimal extraction conditions were as follows:extraction time 1.8 min,extraction temperature 60℃,ethanol concentration 50%,liquid-to-liquid ratio 19:1,microwave power 411 W,the extraction amount of ellagic acid was (82.75±1.05) mg/100 g under these conditions,which was higher than that measured by the traditional hydrochloric acid hydrolysis method under the optimal extraction conditions. The actual results were highly consistent with the theoretical predictions. Therefore,the optimal conditions obtained in this experiment were accurate and reliable and have reference application value. The ability of ellagic acid to scavenge hydroxyl radicals and scavenge DPPH free radicals by microwave assisted solvent method was significantly higher than that of hydroxy acid scavenging ability of ellagic acid obtained by traditional hydrochloric acid hydrolysis method,and the ability to scavenge DPPH free radicals,indicating microwave assisted solvent extraction. The method not only took a short extraction time,but also used less extraction solvent,and better protected the antioxidant activity of raspberry ellagic acid,which could provide a reference for the industrial production of raspberry ellagic acid.