【作者】 赵武奇；

【导师】 殷涌光；

【作者基本信息】 吉林大学 ， 农业机械化工程， 2004， 博士

【摘要】 红景天苷具有抗缺氧、抗疲劳、抗微波辐照、抗毒等抗性作用，还具有对神经系统、内分泌系统的调节作用，具有延缓机体衰老、防止心血管疾病、抗肿瘤以及多种老年性疾病的作用。目前研制出的红景天保健食品存在食用后浓度在体内忽高忽低、利用率低、使用频繁等缺点。研究红景天苷缓释微胶囊化技术，以提高红景天苷的生物利用率、延长作用时间、减少食用次数,这对于更好地发挥其抗疲劳、抗衰老、抗缺氧、抗微波辐照等作用具有重要的意义。本文探讨了微波萃取红景天苷的工艺参数,研究了海藻酸钠和壳聚糖缓释红景天苷的微囊化技术,建立了缓释微囊的神经网络模型，并采用遗传算法对缓释微囊的工艺参数进行优化。微波辅助萃取具有设备简单、适用范围广、萃取效率高、选择性强、重现性好、节省时间、节省溶剂、节能、污染小等众多优点。因此，本文使用微波辅助萃取新技术提取红景天苷。在分析微波萃取机理和影响萃取效果因素的基础上，以红景天粉为原料，以水为溶剂提取红景天苷，考察了固液比、浸泡时间、微波功率、微波处理时间、搅拌时间、提取级数等因素对提取率的影响。确定的最佳工艺条件为：固液比为1：20，浸泡时间为1.5 h，微波功率为低 ，微波处理时间为60 s，搅拌时间为15 min，提取级数为二级。在此条件下红景天苷的提取率为90 %。 海藻酸钠和壳聚糖都具有一定的保健功能,且均是无毒、生物相容性好、可生物降解的天然高分子材料，成膜及成型性好, 价格便宜。它们之间通过静电相互作用可以形成微胶囊的膜，条件温和，非常适合生物活性物质的包埋，是食品工业中水溶性生物活性物质包埋的理想壁材，应用前景广阔。在食品工业领域，本文首次研究了海藻酸钠/壳聚糖对功能性物质红景天苷的微囊化技术。依据红景天苷的特性，筛选出海藻酸钠/壳聚糖微囊化红景天苷的方法，根据乳化试验的结果，确定了一次法制备红景天苷微囊的工艺，研究了不同反<WP=121>应条件如海藻酸钠浓度、海藻酸钠与红景天苷的比例、氯化钙的浓度、壳聚糖的浓度、成膜反应时间及壳聚糖溶液的pH值对海藻酸钠/壳聚糖微囊的包埋率、载药量及缓释性能的影响。试验结果表明：随着海藻酸钠浓度的增大，在海藻酸钠浓度小于2.5%之前，载药量和包埋率逐渐增大, 微胶囊的释放速率也逐渐减慢，之后随着海藻酸钠浓度的增大载药量和包埋率减小，微胶囊的释放速率变大；随着海藻酸钠与芯材比的增大,载药量逐渐减少,包埋率逐渐增大，微胶囊的释放速率减慢；随着壳聚糖浓度的增大，芯材的释放变慢，包埋率增大，但当壳聚糖浓度超过一定值时(0.8%),载药量有所下降；随着氯化钙浓度的增大，载药量和包埋率增大，而在氯化钙浓度过高或过低时，缓释性能都变差；随着成膜反应时间延长，载药量和包埋率逐渐减少，成膜反应时间对微胶囊的缓释性能没有影响；当pH小于5.5时, 随着壳聚糖溶液pH值的升高，载药量和包埋率增大, 微囊膜对芯材的缓释性能逐渐加强，当其大于5.5后, 载药量和包埋率略有下降，缓释性能略有减弱。 人工神经网络是一种非线性动力学系统，是生物神经网络在结构、功能及某些基本特征方面的理论抽象和简化，具有强大的联想功能、记忆功能以及对非线性变量的映射能力。本文依据缓释微囊的特点，在确定输入层和输出层单元、预处理网络数据、选择激活函数、选择训练方法的基础上,首次建立了红景苷缓释微胶囊的人工神经网络模型, 模型的输入参数为海藻酸钠与红景天苷的比例、海藻酸钠浓度、氯化钙浓度、壳聚糖，浓度及壳聚糖溶液的pH值，输出参数为缓释微囊的性能参数，分别是包埋率、载药量和决定系数。网络模型各层的激和函数选用双曲正切函数，最大训练次数设置为300，神经网络的学习算法采用贝叶斯正则化方法，网络的隐层的节点数为12，即网络结构为5—12—3。该网络能较为精确的拟合输入的样本数据，其最大相对误差不超过4%，模型准确可信，可以代替真实试验,该模型的建立为工艺参数的优化打下基础。 遗传算法是近年来在计算机科学领域和优化领域中受到广泛关注的一种拟生物进化理论的仿生学算法，具有适应性强 、全局优化和概率搜索的优点。本文在建立适应度函数、选择编码方案、确定遗传操作及其控制参数的基础上，首次研究了缓释微囊神经网络模型的遗传算法优化技术。得到的最佳的工艺参数为海藻酸钠与红景天苷质量比为2，海藻酸钠的浓度为3%，壳聚糖浓度为0.5%，氯化钙浓度为1%，pH 值为6.35，该工艺参数下载药量、包埋率和决定系数的加权和明显大于单因素试验和二次组合试验的结果,比最好的大14%；且最佳的工艺参数下目标的预测值和试验值基本相符,完全可以满足实际需要。遗传算法用于缓释微囊神经网络模型的工艺参数寻优是完全可行的，它为<WP=122>红景天苷微囊化工艺的实际应用奠定了基础。更多还原

【Abstract】 Salidroside possesses antihypoxia, antifatigue, antimicrowave radiation and antipoison. It can adjust nervous system and endocrine system and have an effect of antiaging, cardiovascular system diseases resistant, antitumor and the aged diseases. The health products presently developed have some drawback, such as rise and fall of drug body concentration, low utilization ratio, frequently eating. So it is important for enhancing function of antihypoxia, antifatigue, antimicrowave radiation and antipoison to study chitosan-sodium alginate microcapsules for salidroside controlled release. It can improve biological utilization ratio, extend period of validity, reduce eating frequency.Firstly, the technological process conditions for microwave assisted extraction (MAE) was studied. Then alginate-chitosan controlled-release salidroside microcapsules were prepared and the neural network model has been established. Finally, the optimum process parameters were obtained by using genetic algorithm.MAE needs simple instrument and can be used for the extraction of various compounds, with characteristics of high efficiency and selectivity, good repetition, less pollution and saving time, solvents and energy. So salidroside was extracted by water as solvent from Rhodiola with MAE. According to analyzing mechanism of MAE and factors influencing extraction, the key factors, including the ration of solid to liquid, soak time, microwave power, microwave irradiation time, stirring extraction period and stages of extraction, were selected and studied for the extraction yield. The optimized technological process conditions were the ration solid to liquid 1:20, soaking for 1.5 h, low grade microwave power, irradiation by microwave for 60 s, stirring extraction period 15 min and the stages of extraction 2. The optimal extraction yield of salidroside from rhodiola was 90 %.Chitosan and alginate, which possess health function and a good nonimmunogenicity. They are enzymatically degradable, poisonousless, inexpensive and easily in film and finished form. The electrostatic interaction of alginate with chitosan，whose reaction are mild, forms a membrane of encapsulation. These semi-permeable membranes are fit for encapsulation of biological active substance. So <WP=124>chitosan and alginate, ideal encapsulation materials for water-soluble substance in food industry, have a growing and promising field for functional compounds microcapsules. Controlled release of salidroside from chitosan-alginate microcapsules was studied. The method was selected on the basis of property of salidroside and emulsification experments. The effect of process parameters, such as alginate concentration, ratio of alginate weight to salidroside weight, chitosan concentration, reaction time and chitosan solution pH value, on drug loading, encapsulation rations and release property of alginate-chitosan microcapsules was studied. The results indicated that when alginate concentration was below 2.5 %, drug loading and encapsulation ration gradually increased and release property of alginate-chitosan microcapsules was gradually slowed with its increasing. But when it was beyond 2.5 %, the results was contrary ；Drug loading gradually decreased , encapsulation ration gradually increased and release property of alginate-chitosan microcapsules was gradually slowed with the ratio of alginate weight to salidroside weight increasing； Release property of alginate-chitosan microcapsules was gradually slowed , encapsulation ration gradually increased with chitosan concentration increasing, but when it was beyond 0.8 %, drug loading decreased ； Drug loading and encapsulation ration increased with CaCI concentration increasing, release property became bad when CaCI concentration went to extremes；Drug loading and encapsulation ration gradually decreased as the forming time was extended, the forming time had no effect on release property；When chitosan solution pH value was below 5.5,drug loading and encapsulation ration gradually increased and release property of alginate-chitos更多还原