Study On Extraction And Purification Of Anthocyanins From Purple Sweet Potato, The Antioxidant Activitv Of Anthocvanins And The- Preparation Of Maltodextrin From The Extraction Residue

Purple sweet potato anthocyanin is a kind of good performance of natural pigment.This thesis mainly studied on the technology conditions of extraction from purple sweet potato, separation and purification, and using the extraction of purple sweet potato residue to make maltodextrin,also on the antioxidant activity.Experiment with fresh purple sweet potato as raw material, Aqueous solution of citric acid as extraction agent,the use of high-pressure broken pretreatment and ultrasonic extraction technology and sedimentation and macroporous resin adsorption, separation, and purification of anthocyanins.The extraction of anthocyanins from purple sweet potato by single factor and orthogonal test.The optimal conditions for the extraction of anthocyanins in purple sweet potato as:2.0% aqueous solution of citric acid as extraction solvent, solid-liquid ratio of 1:30, a temperature of 60℃, extraction time to 40 min,The crude extraction of anthocyanin was purified by AB-8 macroporous resin.Through static and dynamic two ways test of adsorption and desorption, the optimum purification conditions:the static adsorption was 2 hours to reach basically saturated, the crude extracts of pH was in the 1 to 3 range in which the effect on resin adsorption was not obvious,the 70% ethanol water solution was the best desorption effect.Under the optimum extraction condition, the anthocyanin extraction rate was 18.97% from purple sweet potato and the pigment value was 119.We also used the purple sweet potato pigment extraction residue as raw material, with enzymatic hydrolysis to make maltodextrin. Through orthogonal test to optimize the process conditions, then researched the physical and chemical properties of the sample. Through the experiment,we get the best enzymatic hydrolysis conditions:enzymolysis temperature of 90℃ for 60 min, enzyme dosage for 20 u/g,with maltodextrin DE value of 15.69, the solubility of samples was 98.14%. Solubility, sensory and other physical and chemical index were higher than the national standard.After the extraction,purification and vacuum freeze drying,we studied the antioxidant activity.the anthocyanin from purple sweet potato showed high scavenging effects on three free radicals of · OH、O2-、DPPH ·. With the concentration increased gradually, the anthocyanins antioxidant activity also increased, when the concentration reached to 5mg/mL, the antioxidant activities of pure pigment are closed to Vc.