【作者】 汪廷彩；

【导师】 苏平；

【作者基本信息】 浙江大学 ， 食品科学， 2004， 硕士

【摘要】 南瓜（Cucurbiat moschata Duch），为葫芦科南瓜属植物的果实，栽培简单，产量高，易于贮运，而且营养丰富，深受人们的喜爱。本研究以我国主要栽培种的黄狼南瓜品种为原料，从其粉体中提出天然食用黄色素，对其组分分析，结果发现南瓜黄色素中主要含有三种类胡萝卜素：叶黄素、β-胡萝卜素和α-胡萝卜素。叶黄素对老年性黄斑变性病（AND）具有良好的预防作用，通过过滤蓝光和清除自由基而对眼睛具有良好的保护作用，有研究还显示，叶黄素对白内障和癌症都有预防作用。本研究目的在于寻找南瓜黄色素的最佳提取工艺，而后从所制备的南瓜黄色素粗品中分离纯化出叶黄素，并初步探讨其清除羟自由基和抑制猪油自氧化的能力，为南瓜综合利用提供可靠的理论依据。本研究的主要结果如下： 首先对苯、氯仿、二氯甲烷、环己烷、石油醚、乙醚、丙酮、四氢呋哺、乙醇九种溶剂的提取效果进行对比实验，其效果依次为：四氢呋喃＞氯仿＞二氯甲烷＞乙醇＞乙醚＞苯＞石油醚＞环己烷＞丙酮，而后对混合溶剂优选，结果以四氢呋喃-乙醇的提取效果最佳，最后经过正交实验，结果显示以四氢呋喃-乙醇（3：1）为提取溶剂，温度为20℃，料液比为1：5，超声波辅助提取40min连续提取五次为最佳提取工艺，得到的南瓜黄色素的提取率为4.94％。 对南瓜色素皂化品进行组分分析，HPLC条件为Waters 510泵，20μl微量进样器，Waters996检测器，Millenium色谱数据分析系统，大连依利特科学仪器有限公司提供的C₁₈色谱柱（150mm×4.6mm，5 μm），流动相为甲醇-二氯甲烷-乙腈-水（38：32：29：1，V／V），检测波长450nm，流速0.6ml／min，结果发现其中主要含有三种成分：叶黄素、β-胡萝卜素和α-胡萝卜素，其中叶黄素含量为27.364mg／g，β-胡萝卜素的含量为6.802mg／g。利用叶黄素与胡萝卜素存在结构上的差异以及在正己烷中的溶解度的差异，对南瓜色素中的叶黄素进行分离纯化，由HPLC分析结果显示，叶黄素纯化后得率为80.5～86.3％，纯度为90.5～94.6％。 对南瓜色素的理化特性进行研究表明，该色素对大多数金属离子是稳定的，但三价的铁离子会使该色素遭到破坏，当有Ba²⁺存在时会产生不明沉淀，此外，该色素对pH和防腐剂都比较稳定，温度在不超过100’C时对色素的破坏作用也不大，但高温处理则使其组分分解，南瓜色素对光照十分敏感。分光光度法测得皂化品中总类胡萝卜素含量为29.22%，粗品中含量为5.07%。 采用抗坏血酸一CuZ十一H八一酵母体系产生的经自由基为体外模型，对制备产品清除轻自由基的能力进行研究，结果发现南瓜黄色素的皂化品和纯化碑能有效清除轻自由基，最佳的浓度为0.Zmg/m1。在猪油自氧化实验中，在低浓度范围（<0.2%）南瓜色素同样表现出了良好的抑制作用，而且在不超过VC浓度的时候与VC具有良好的协同抗氧化作用。· 综上所述，南瓜黄色素为天然类胡萝卜素，从南瓜中提取南瓜黄色素为其综合利用提供了一条有效的途径，尤其从中制备分离出叶黄素开发高档产品提供了良好的理论依据。更多还原

【Abstract】 Pumpkin (Cucurbiat moschata Duch) is the fruit of cucurbitaceous plants. Due to its easy growth, high yield, long shelf life and abundant nutriments, pumpkin is very popular in China. In this study, Chinese Huanglang pumpkin was selected as raw material. After the composition analysis of the natural food yellow pigment extracted from the pumpkin powder, the result indicated that there were three major carotenoids: a -carotene, B -carotene and lutein. Lutein can effectively reduce the risks of age-related macular degeneration (AMD). By filtering blue light and quenching free radicals, lutein protects against cataracts and cancers. The extraction processing of pumpkin yellow pigment from pumpkin powder was optimized. Besides, a simple method for isolation and purification of lutein from pumpkin yellow pigment was developed. The stabilities of the pigment were conducted. To testify its function, the scavenging free radical activities were evaluated. All the studies provide the basic theory for the general utilization of pumpkin. The results were shown as follows:First of all, the extractability of 9 organic solvents were compared by the wavelengh scanning. The sequence from the better to the worse was: tetrahydrofuran (THF) > chloroform > dichloroform > ethanol > ethyl ether > benzene > petroleum ether > cyclohexane > acetone. Furthermore, when ethanol was added to THF, the OD450nm value of the extract increased rapidly. Taking the factors of temperature, organic agent and ratio of material and solvent for combined experiment, the best extraction processing was as follows: THF-EtOH (3:1,v/v) as solvent, temperature at 20℃, ratio at 1:5. Ultrasonic processing for 40min, repeating for 5 times, can improve the extraction processing. Evaporating solvent of the extract at low temperature (<40℃), the last yield of pumpkin yellow pigment was 4.94%.After saponification of the pigment, the extract was analysed by HPLC.The HPLC system used throughout this study consist of a Waters 510 pump (Waters, Milford, MA), a sample injector with a 20ul loop, and a Waters 996 photodiode array detector, Millenium chromatography data system. The column used was a reversed phase ultrasphere C18 column. The mobile phase was methanol/dicholomethane/acetonitrile/water (38:32:29:1,v/v), and the flow rate was 0.6ml/min. The fluent was monitored at 450nm. The chromatography showed that there were three carotenoids: a -carotene, b -carotene and lutein. The contents of lutein and B -carotene in the pigment were 27.364mg/g and 6.802mg/g respectively. Due to the solubility of lutein in hexane, lutein was isolated and purified from the saponified extract. By HPLC analysis, the average yield of lutein was 85.4% and the purity was 92.5%.The pigment was stable to pH, preservatives, temperature not more than 100癈 and most metal ions. When there was Fe3+, it was destroyed badly. Otherwise, Ba2+ can produce the undefined precipitate. The pigment was sensitive to sunlight and high temperature (>100癈). Spectrophotometer measuring, the total content of caroteinoids in saponified product was 29.22%, and in the crude extract was 5.07%.Using VC-CUSO4-H2O2 system to study its scavenging activity, the result indicated that both the saponified extract and the purified lutein could quench the hydroxyl radical ( OH). The best concentration of scavenging was 0.2mg/ml. In the lipid self-oxidation experiment, the product showed a strong inhibition of oxidant at low concentration (<0.2%). Furthermore, VC can enhance the antioxidant ability of the pigment.In general, pumpkin yellow pigment was natural carotenoids. Extracting the pigment from pumpkin powder, especially isolation and purification of lutein, provide a new way for developing pumpkin products.更多还原