The Study On The Extraction And Purification And Stability And Antioxidant Activities Of Anthocyanins From Purple Sweet Potato

Inartificial anthocyanin is a kind of water-solubility coloring matter which is widely indwelled in plant, and it belongs to flavones compound. AS a result of its vivid color and luster, anti-oxidation and other function of health care, in order to making people's works and lives better, it has been put into industrialization produce. Purple sweet potato is high output, easy planted, become a inexpensive way to obtain anthocyanin, so recently years, the anthocyanin distilling from it has become a very hot research study.The present thesis was focused on the anthocyanins from purple sweet potato cultivated in Hebei Academy of Agricultural Sciences, including technology conditions of extractiom and purification, component analysis, stabilities and antioxidant activities.The optimum extraction conditions have been obtained, which included extraction temperature was 60℃, the concentration of extraction reagent was 5% formic acid, the ratio of purple sweet potato powder to the extraction reagent was 1:10, extraction time was 2 hour for 3 times, after the crude anthocyanin pigments was purified by AB-8 Macro-porous Resin, the color value increased to 20.4.The chemical components in extraction of purple sweet potato were analyzed by HPLC-electrosprary ionization-mass spectrometry(ESI-MS) and the structure was elucidated accoding to mass-to-charge ratio (m/z) of molecule ionic peak, the fragmental and reference. The major anthocayanin is 3-O-(6-O-trans-caffeyl-2-O-β-glucopyranosyl-β-glucopyranoside)-5-O-β-glucoside peonidin.The purple sweet potato anthocyanins had a better heat stability. Under 60℃,the stability very good, and the save ratio next to 100%. The purple sweet potato anthocyanins had a strong compression resistance characteristic, at the pressure is 500MPa, disposal 15min, the anthocyains still hold the line. At the different pH value, anthocyanins stabilities are different, at a strong acidity condition(pH≤3), the change of colour and characteristic absorb spectrum are unconspicuous, however, at the alkalescence condition, the anthocayanins showed a instability characteristic. The antioxidant activities of anthocayanin from purple sweet potato(yan 176)were studied with three methods: scavenging activity against diphenylpicrylhydrazyl radical, superoxide anion radical and hydroxyl radica1, and compared with Vc. As the result: the anthocayanin from purple sweet potato showed high scavenging effects on·OH, O2.- and DPPH·. But the antioxidant activities of crude pigment obviously lower pure pigment and Vc. When the concentration reached to 5mg/mL, the antioxidant activities of pure pigment are closed to Vc.