【作者】 陈杰；

【导师】 张连富；

【作者基本信息】 江南大学 ， 农产品加工与贮藏工程， 2011， 硕士

【摘要】 紫甘薯是璇花科一年生草本植物,其富含的花青素具有着色、营养和保健等多重作用,因此紫甘薯是一种极具开发价值的天然色素资源。本文针对紫甘薯色素提取纯化及其稳定性等问题进行了研究:在单因素试验的基础上,由响应面试验设计得到紫甘薯色素的最佳提取工艺为:以酸化乙醇（浓度80%,v/v）为提取剂,提取温度60℃,提取时间1h,料液比1:30,紫甘薯色素最大得率为12.47mg/g,最佳提取次数为2次。紫甘薯色素粗提物中含有大量的杂质,经试验选取AB-8大孔吸附树脂作为纯化紫甘薯色素用树脂,其纯化条件为:样液浓度为1.80mg/mL,样液pH值为3,样液流速为3mL/min,洗脱液为含1%盐酸的70%乙醇水溶液,洗脱液流速为3mL/min,洗脱体积为700mL,纯化回收率为62.37%,经纯化紫甘薯色素的色价为21.45,纯度为9.22%。作为稳定性较差的花色苷类色素,不同使用条件下的稳定性是影响紫甘薯色素使用范围及作用效果的重要基础。试验结果表明:照射处理7h后,紫外灯的色素保存率最低仅为50.64%,室外自然光为71.98%,室内自然光为82.22%,而暗箱内为89.90%最高,紫甘薯色素在光照条件下的稳定性较差;在pH值为2～11时,紫甘薯色素溶液的颜色由深红色逐渐变成蓝色,对其全波长扫描可知,随着pH值升高,λ_max向长波方向移动,紫甘薯色素溶液的颜色强度随着pH值的增加呈先下降后上升趋势;随着温度的升高和加热时间的延长,紫甘薯色素保存率随之下降;Al³⁺对紫甘薯花色苷略具护色作用,而Fe³⁺、Cu²⁺、Zn²⁺、Pb²⁺不具护色作用;随着氧化剂浓度的增加以及氧化时间的延长,紫甘薯色素保存率明显下降;Na2SO3溶液浓度越高,紫甘薯色素保存率越低,说明Na2SO3能降低色素稳定性;苯甲酸钠和山梨酸钾对紫甘薯色素稳定性影响很小;单宁、对羟基苯甲酸和咖啡酸能明显地增加紫甘薯色素的稳定性,且各色素溶液的最大吸收波长也均发生红移。糖类能增加紫甘薯色素的稳定性,而且浓度越高就越有利于紫甘薯花色苷的稳定。山梨酸钾和亚硫酸钠的添加比例为1:1,添加量为5ppm,抗坏血酸钠的添加量为1ppm,能增强紫甘薯色素稳定性,且经试验验证,确实能起到强化色素稳定性的作用。更多还原

【Abstract】 Purple sweet potato （convolvulaceae） was an annual herb. It was rich in anthocyanin with nutrition and health function, etc. Therefore, it was a natural pigment resource to be exploited. In the present thesis, extraction, purification, stability and stablization of purple sweet potato pigment （PSPP） were studied and the results were as follows:On the basis of single factor experiment, reponse surface methodology（RSM） was employed to optimize the extraction conditions of PSPP. The results were: temperature 60℃, time 1h, solid-liquid ratio 1:30, acidified ethonal concentration 80%, and the extraction yield was 12.47mg/g.The optimum extraction frequency was twice. Lots of impurities were existed in the crude PSPP. Based on experiment, AB-8 macroporous adsorption resin（MAR） was chosed to purify PSPP, and the purification conditions were: the concentration, pH and flow velocity of the sample were 1.80mg/mL, 3 and 3mL/min, respectively. The eluent was 70% ethanol aqueous with 1% hydrochloric acid and its flow velocity was 3mL/min. Elution volume was 700mL. The purification recovery percent was 62.37%. The color value and rate of purification of PSPP after purification was 21.45 and 9.22%, respectively.PSPP was unstable. In ultraviolet lamp, outdoor/indoor natural light and dark chamber for 7h, the retention of PSPP were 50.64%,71.98%, 82.22%, 89.90%, respectively. Based on this, the stability of PSPP was bad in the presence of light, especially ultraviolet lamp. With full wavelength scanning in differenet pH values from 2 to 11, the color of PSPP changed from deep red to blue, andλ_max moved to the longer wavelength with its CI decreasing firstly and then increasing as the increasing of pH. With the rise of the heating temperature and prolong of heating time,its stability decreased. Al³⁺ could increase the stability of PSPP, but Fe³⁺, Cu²⁺, Zn²⁺, Pb²⁺ would decrease the stability of PSPP. Oxidant would decrease the stability of PSPP and the PSPP solution would fade as the rise of the concentration of oxidant and prolong of oxidation time.Na2SO3 did harm to the stability of PSPP. Sodium benzoate and potassium sorbate showed little influnce on the stability of PSPP. Tannin, p-hydrobenzoic acid and coffeic acid could effectively increase the stability of PSPP, and itsλ_max moved to the longer wavelength. Carbohydrate could increase the stability of PSPP, and the higher the concentration of carbohydrate was, the more stable PSPP was.Sorbic acid potassium, sodium sulfite and ascorbate acid sodium added in PSPP could stablized its stability. After experiment, the rate of sorbic acid potassium and the sodium sulfite added in PSPP was 1:1（m/m）, and its dosage was 5ppm with 1ppm ascorbate acid sodium in it. Effects of light, temperature, oxidative and pH were studied to prove that it was correct.更多还原