The Study Of The Extraction,Stability And Antioxidation Of Anthocyanidin From Purple Sweet Potato

In recent years, along with the medicine toxicological and biological research gone deep, the people discovered the synthetical food pigment was harmful to human body more or less; therefore, the synthetical pigment was gradually replaced by natural pigment. The anthocyanidin is a kind of water-soluble pigment that people is most familiar with. Because it has high security, easy coloration and many physiological functions, the majority country all allows it to use in food coloration. The purple sweet potato is paid more attention by people because it richly contains anthocyanidins, has bright colour and high biological activity.The method of separating and content determining anthocyanidin in purple sweet potato by HPLC was firstly established inland. Furthermore, the craft condition of extraction, the stability and antioxidation were synchronously studied. The results indicated:1. HPLC Method: HPLC was run on Lichrospher 5 - C18 column (150mm×4.6mm, 5μm, HanBang, JiangSu) at 35 and monitored at 530nm. The following solvents in water with a flow rate of 0.3 mL/min were used: (A) acetonitrile, and (B) 10% acetic acid. The elution profile was a linear gradient elution for B of 90% to 80% during 30min in solvent A. In all samples 20μL was injected. Through determining anthocyanidin in six kinds of purple sweet potato, each breed had different components and their contents were diverse. The product rate of anthocyanidin in Zi A₄, ZheZi and JingShu 6th,Zi A₁,EZi and ChuanShanzi were 7.6058,7.5162,7.1663,6.1608,5.5458å’Œ5.0249 mg/g dry weight respectively .2. The single factor parallel experiment was researched in extraction solvent,solvent concentration,extraction temperatue,extraction time,extraction rate of solid to liquid. In order to optimize the craft condition, the orthogonal experiment was carried on. The optimal craft condition: the sample had been extracted in 10% acetic acid at 40℃and solid 1 to liquid 20 for 60min. the content of anthocyanidin extracted in the craft condition was 150.01μg/mL, and the product rate was 7.5mg/g (dry weight).3. Through investigating the macro-porous resin HPD-700 in absorption time, absorption temperature,absorption pH,desorption time,desorption ethanol concentration,desorption degree and circulation operational performance. The optimal absorption condition: absorption time was 12h, absorption temperature was 20°C and absorption pH was 2.5. The absorption rate was 91.82±0.34%. The optimal desorption condition: desorption time was 30min,desorption ethanol concentration was 70%,desorption degree was 2. the desorption rate was 93.42±1.13%. Circulation operational performance of macro-porous resin HPD-700 was better. In optimal absorption and desorption condition, the product rate was 45mg/g (dry weight) and purification multiple was 6.4. Comparing the stability of anthocyanidin in room light,ultraviolet radiation,boiling-water bathing,autoclave and different pH, the result indicated, light influenced the stability of anthocyanidin less and high temperature influenced more, specially autoclave. The conservation ratio of anthocyanidin was 92.31±0.79% in natural light after 30 days, 90.92±1.91% in ultraviolet radiation after 4 hours, 69.05±0.79% in boiling-water bathing after 4 hours and 63.75±0.83% in autoclave after 20 minutes. The stability of anthocyanidin was obviously diverse in different pH. The stability was good below pH5.0 and rapidly dropped along with pH rising. The relative conservation ratio of anthocyanidin was 80% upwards below pH5.0 and less than 15% above pH9.0 after 4 days.5. researching on anthocyanidin scavenging free radical, the result shown, anthocyanidin possessed better scavenging ability on superoxide anion,hydroxyl free radical and DPPH·free radical. In scavenging superoxide anion, anthoyanidin IC₅₀=0.25mg/mL and Ascorbic Acid IC₅₀=0.3mg/mL, the scavenging superoxide anion capacity of anthocyanidin was better than that of Ascorbic Acid above 0. 23mg/mL and reversed below it. In scavenging hydroxyl free radical, anthoyanidin IC₅₀=0.08mg/mL and Ascorbic Acid IC₅₀=0.19mg/mL, the scavenging hydroxyl free radical capacity of anthocyanidin was obviously better than Ascorbic Acid. In scavenging DPPH·free radical, the scavenging ratio of anthocyanidin,Ascorbic Acid,α-Tocopherol and BHA was studied. Anthoyanidin IC₅₀=2μg/mL, Ascorbic Acid IC₅₀=1.2μg/mL,α-Tocopherol IC₅₀=32μg/mL and BHA IC₅₀=78μg/mL, the scavenging DPPH·free radical capacity of Ascorbic Acid was obviously better than anthocyanidin below 5μg/mL,α-Tocopherol and BHA can hardly scavenge it. When above 5μg/mL, the order: anthocyanidin > Ascorbic Acid>α-Tocopherol>BHA. The scavenging ratio of anthocyanidin and Ascorbic Acid was near 100% above 10μg/mL; therefore, the difference was indistinctive.