【作者】 李金林；

【导师】 涂宗财；

【作者基本信息】 南昌大学 ， 粮食、油脂及植物蛋白工程， 2007， 硕士

【摘要】 紫甘薯（purple sweet potato）属旋花科一年生草本植物，其富含抗氧化作用的天然色素，是一种提取花色苷较好的资源，引起了国内外的广泛关注。本论文以紫甘薯为原料，对紫甘薯花色苷检测方法、提取工艺、酶解助提取工艺、膜分离以及紫甘薯花色苷在加工过程中稳定性进行了研究，研究结果如下：本论文以亚硫酸钠为漂白剂，采用漂白法对紫甘薯花色苷进行定量检测，分别对检测pH值、检测波长λmax、吸光度线性范围、漂白剂用量、漂白时间进行了研究，结果表明：采用漂白法检测紫甘薯花色苷的最佳检测条件为：检测pH值为3、检测波长λmax为528nm、吸光度线性范围为0.2～2.9、漂白剂用量为3g／10mL、漂白时间为10min。以苋菜红为标样，绘制标准曲线，标准曲线线性回归方程为：y＝42.767x＋0.8947，其中，Y——苋菜红浓度，μg／g；X——吸光度。以此法检测，紫甘薯样品中花色苷含量为：368.53mg／100g。与乙醇和柠檬酸酸化乙醇相比，柠檬酸溶液对紫甘薯花色苷的提取效率较高，以柠檬酸溶液为提取剂，紫甘薯花色苷最佳提取条件为：提取次数为两次、提取温度60℃、提取时间1小时（第二次30min）、柠檬酸浓度2％、液固比40∶1，在此条件下进行紫甘薯花色苷的提取，得紫甘薯花色苷溶液色价为0.8013，花色苷提取率为93.9％。在进行酶解助紫甘薯花色苷提取研究发现：果胶酶不适用于紫甘薯花色苷的提取中，纤维素酶助紫甘薯花色苷提取的最佳酶解条件为：pH值4.5，酶解温度35℃，加酶量0.1％，底物浓度1∶5，酶解时间30min。紫甘薯花色苷粗提液经由100nm超滤膜过滤后杂质含量下降，花色苷含量得到提高，杂质的去除率达38％，花色苷的截流率为27.49％，花色苷含量由原来的32mg／g提高至37.42 mg／g。紫甘薯花色苷稳定性研究结果表明：紫甘薯花色苷在酸性条件下较稳定，并随着pH值上升花色苷稳定性先下降后上升，在pH 5时，稳定性最差。紫甘薯花色苷对温度敏感，温度越高对花色苷的破坏越大；在卫生允许范围内，限量金属离子：Pb²⁺对紫甘薯花色苷能起到一定稳定作用：Cu²⁺对紫甘薯花色苷具有增色作用；Fe³⁺对紫甘薯花色具有保护和破坏双重作用，总体看保护作用大于破坏作用；还原剂D—异抗坏血酸钠对紫甘薯花色苷有很大的保护作用；漂白剂亚硫酸钠和护色剂亚硝酸钠对紫甘薯花色具有破坏作用，甚至起漂白作用；防腐剂苯甲酸钠对紫甘薯花色苷稳定性没有不良影响。更多还原

【Abstract】 Purple sweet potato （Ipomoea batatas）, a Convolvulaceae annual herb with rich antioxidative natural pigment, is a recommendable resources for anthocyanin pigment extraction, has caused universal concern.The present thesis was focused on the detection method of pigment from purple sweet potato, technology conditions of extraction and extraction assisted by enzymolysis, technology of purification by membrane, stabilities of anthocyanin pigment from purple sweet potato.Bleaching technology, a rapid method for determination of anthocyanins pigment from purple sweet potato by bleaching, has been researched in this paper. Sodium sulfite used as bleaching agent, the appropriate detecting condition of bleaching was: pH value 3, detection wavelength of 528 nm, linear range of absorbency 0.2～2.9, the dosage of Na₂SO₃ 0.3 g/10 mL, bleaching time 10 min. the equation of linear regression of amaranth standard curve was: y=42.767x+0.8947;y---concentration of amaranth, ppm; x---absorbency of amaranth solution. The concentration of anthocyanin in purple sweet potato is 368.53 mg/100 g detected by bleaching.By contrast, citric acid was better than alcohol and acidulated alcohol as extractant. Then the optimum extraction conditions have been obtained, which included temperature 60℃, 2% hydrochloric acid, the ratio of sweet potato powder to the extraction reagent 1:40, extracting time 1 hour twice （the second time 30 min）. under the optimum extraction conditions, the color calue of anthocyanins pigment solution was 0.8013, the extraction ratio was 93.9%.Pectinase and cellulose were used to assisted extraction of anthocyanins pigment from purple sweet potato; the result showed that it was not beneficial to extraction when pectinase added in. The optimum enzymolysis-extraction conditions were: enzyme concentration 1 g/kg, temperature 35℃, pH 4.5, taking time 30 min. The crude pigment was purified by ceramic membranes with 0.1μm pore size, the interception ratio of anthocyanidins and removal rates of impurity have been determined. The interception ratio of anthocyanidins was 27.4%, the removal rates of impurity was 38% and the concentration of anthocyanins pigment increased from 32 mg/g to 37.42 mg/g after process of membrane filtration.The stabilities of anthocyanin extracting from purple sweet potato were conducted. The results showed that the pigment had better stability to be kept in low pH value, and was sensitive to temperature, the stability of the pigment dropped notably in heating. Metal ions had little influence to this anthocyanins pigment, among them; Cu³⁺ deepened the color more than Pb²⁺, while Fe³⁺ deepened the color little based on combining of the disruptive and protective properties of Fe³⁺ to anthocyanins pigment.The effects of Food Additives on stabilities of anthocyanins pigment have been researched, the result shown that D-isoascorbate can protected the anthocyanins pigment, while Na₂SO₃ and NaNO₂ breakdown it, and Sodium Benzoate has no harmful effects on anthocyanins pigment from purple sweet potato.更多还原