Study On Ultrasonic Extraction Of Anthocyanins From Blueberry Pomace And Its Structure And Properties

Three extaction methods under dual,single frequency ultrasound and no ultrasound,were used to extract anthocyanins from blueberry pomace.The anthocyanins were purified by AB-8 macroporous resin.Then they were processed to powders after concentration and desiccation.The stability,antioxidant activity and composition of the blueberry anthocyanins were studied to provide theory basis for the development of blueberry anthocyanins and application of ultrasonic technology in extracting anthocyanins.After the single factor and orthogonal experiments,the maximal extraction rate was obtained when extracted with 360 W ultrasonic power and 60%alcohol at 53? with solid-liquid ratio of 1:17(g:mL)for 43 min.The extraction rate was affected by frequency and a maximal amount of extractive was obtained with the assistant of dual-frequency ultrasound.The blueberry pomace anthocyanins were purified by AB-8 macroporous resin.The optimum condition of purification was obtained to be 3 hours of adsorption and desorption equilibrium time.A maximum adsorption rate was reached when the sample flowed into the resin column at 50? and pH of 2 at a flow rate of 1mL/min.A maximum desorption rate was reached when the anthocyanins collected at 50? and pH of 2 with 60%alcohol(4BV)at a flow rate of 1mL/min.The anthocyanins were processed to powders after purification,concentration and desiccation.The Color Value of anthocyanins was 66.23 after ultrasound extraction and 64.71 after the extraction without ultrasound and the values of purity came out to be 67.30%and 66.64%.The stability of blueberry anthocyanins was studied after the extraction and purification.Anthocyanins were found to be stable in acid environment and unstable with light or high temperature.A moderate amount of glucose can improve the stability of anthocyanins.Ultrasound can enhance the antioxidant ability of anthocyanins.HPLC-ESI-MS/MS was used to identify and analyze the composition of blueberry anthocyanins and 7 kinds of anthocyanins were detected as Cyanidin-3-glucoside,Delphinidin-3-arabinosidechloride,petunia-3-glucoside,petunia-3-arabinoside,peony-3-glucoside,Malvidin-3-glucoside and Delphinidin-3-glucoside.