聚合乳清蛋白基微胶囊技术及其在功能性食品中的应用

发布时间：2018-05-09 10:21

本文选题：聚合乳清蛋白 + 微胶囊　；参考：《吉林大学》2017年博士论文

【摘要】：乳清蛋白作为干酪加工过程中的副产物,其具有极高的营养价值和多种功能特性,对其进行合理的开发与利用不仅解决了环境的污染问题,更能为食品、医药等领域带来一种优质的蛋白来源。乳清蛋白的成膜性及凝胶性是其重要的功能特性,在乳清蛋白溶液经加热时,β-乳球蛋白间可发生二硫键的形成,交联成致密的网状结构,表现为聚合乳清蛋白的形成。盐离子如钙的加入可以形成非共价键“钙桥”增强聚合乳清蛋白分子间的交联,形成凝胶结构。本文主要对乳清蛋白的以上性质进行研究并为其在微胶囊壁材上的应用打下了基础。利用聚合乳清蛋白对生物活性物质进行包埋,观察其作为壁材的保护作用和包埋效果,并遵循来源于乳,应用于乳的原则将微胶囊应用于共生发酵乳制品。本文首先对聚合乳清蛋白进行制备和表征。以粒径分布、表面电位、粘度、二级结构与基团以及变性度为指标研究不同乳清蛋白浓度(8-16%)、p H(7.0-8.0)、加热温度(70-90℃)、加热时间(5-30 min)条件下所制备的热诱导聚合乳清蛋白的理化特性。实验结果表明,加热后与未加热的乳清蛋白溶液相比,性质发生了显著的变化,其中粒度的先减小后增大,游离巯基数量的先增加后减少,疏水性的先增强后减弱,α-螺旋和暴露肽键的先增多后减少,粘度的持续增加,α-乳白蛋白及β-乳球蛋白单体的减少,均表征了乳清蛋白的变性和聚合的发生。其次,依据上述实验结果,选定对乳清蛋白聚合有显著影响的三个因素,研究了不同乳清蛋白浓度(11-15%)、加热温度(70-80℃)、加热时间(5-15 min)条件下制备的聚合乳清蛋白钙诱导凝胶的强度及其在人工消化液中的溶解率与水解程度。实验结果表明,钙离子的加入可以有效提高聚合乳清蛋白的凝胶强度,在一定范围内,乳清蛋白的聚合程度越强,钙诱导凝胶的强度越大,证明分子间的交联作用越强,从而有结构更致密的网状结构产生,会对芯材有更好的包埋和保护作用。聚合乳清蛋白钙诱导凝胶在人工胃液中4h的溶解率小于30%,在人工小肠液中4h溶解率可达100%。最后,将聚合乳清蛋白用于生物活性物质的包埋制备微胶囊,并将其应用于共生牛/羊奶酸奶,具体的实验结果如下:(1)人参皂苷在食品中的应用受到了其颜色和苦味的限制。故利用聚合乳清蛋白对人参皂苷进行包埋可以有效地掩盖其苦味和颜色。利用聚合乳清蛋白结合锐孔-凝固浴法制备的人参皂苷微胶囊包埋率可达97.15±1.95%,在模拟消化实验中,人参皂苷在人工胃液中的释放率约为20%,而在人工小肠液中可完全释放。将人参皂苷微胶囊用于共生酸奶的制备,结果显示,人参皂苷微胶囊酸奶的感官评价接受性(3.7分)显著高于直接添加人参皂苷的酸奶(1.6分)(p0.01)。人参皂苷微胶囊的添加显著地增强了酸奶的持水力并提高了酸奶的蛋白质含量(p0.01)。(2)益生菌被广泛应用于功能性发酵乳制品,其中嗜酸乳杆菌对胃酸耐受性差,聚合乳清蛋白基微胶囊可有效提高消化过程中嗜酸乳杆菌的存活率。利用聚合乳清蛋白结合锐孔-凝固浴法制备的嗜酸乳杆菌微胶囊包埋率可达92.90±3.90%。酸奶的保质期实验结果显示,添加益生菌微胶囊的酸奶与对照组相比,益生菌的含量没有显著差异,证明在长达10周的储藏期内,微胶囊稳定性良好。酸奶经人工小肠液消化后可以将微胶囊中的菌体释放,存活数仍能达到105cfu/m L以上。说明食用添加益生菌微胶囊的酸奶,可以保证大量的益生菌在经消化后到达人体肠道内定殖,并对人体健康发挥积极作用。(3)利用聚合乳清蛋白的成膜性对嗜酸乳杆菌LA-5进行微胶囊化,利用冷冻干燥法,制备益生菌微胶囊冻干粉。结果表明,聚合乳清蛋白的吸湿性及对嗜酸乳杆菌LA-5的保护性与糊精相比没有显著性差异。将各组酸奶进行10周的保质期实验,结果表明冻干型嗜酸乳杆菌微胶囊在用于酸奶的制备时,均能将菌体充分释放,使其在发酵过程中大量繁殖以达到理想水平。同时可以说明,冷冻干燥的过程及聚合乳清蛋白基壁材的使用并没有对菌体的增殖能力及生物活性产生不利影响。综上,本文系统地对不同条件下制备的聚合乳清蛋白的理化性质进行了研究与表征,并研究其凝胶特性在微胶囊壁材领域应用的可行性和优越性,为其作为微胶囊壁材对一系列生物活性物质的包埋与应用提供了理论依据。通过具体地将聚合乳清蛋白作为壁材制备人参皂苷以及嗜酸乳杆菌微胶囊,并将其应用于发酵乳制品,验证了聚合乳清蛋白用于微胶囊壁材应用的可行性,并为其在食品工业领域的应用提供了理论基础和技术支持。
[Abstract]:Whey protein, as a by-product of cheese processing, has high nutritional value and many functional properties. The rational exploitation and utilization of whey protein not only solves the pollution problem of the environment, but also brings a high quality protein source for food and medicine. The membrane and gel properties of lactoprotein are its important functions. Characteristics, when the whey protein solution is heated, the formation of two sulfur bonds between beta lactalbumin can occur and cross linked into a compact reticulate structure, showing the formation of a polymerized whey protein. The addition of salt ions, such as calcium, can form a non covalent bond "calcium bridge" to enhance the cross-linking of the polymer whey protein molecules and form a gel structure. This paper is mainly to whey. The above properties of the protein have been studied and laid a foundation for its application on the microcapsule wall material. The bioactive substances are embedded by polymeric whey protein to observe the protective effect and embedding effect of the wall material, and follow the principle of milk. Polymerized whey protein was prepared and characterized. The physicochemical properties of the different whey protein concentration (8-16%), P H (7.0-8.0), heating temperature (70-90 degrees C) and heating time (5-30 min) were studied by the particle size distribution, surface potential, viscosity, two grade structure and group and denaturalization degree. The results showed that the physical and chemical properties of the heat induced whey protein were prepared under the conditions of heating time (5-30 min). After heating, compared with the unheated whey protein solution, the properties have changed significantly, in which the grain size decreases first and then increases, the amount of free sulfhydryl group increases first and then decreases, the hydrophobicity first increases and then decreases, the increase of alpha helix and exposure peptide bonds, the continuous increase of viscosity, the reduction of alpha lactate and beta lactoglobulin monomer. Less, characterizing the denaturation and polymerization of whey protein. Secondly, according to the experimental results mentioned above, three factors which have significant influence on whey protein polymerization are selected, and the strength of different whey protein concentration (11-15%), heating temperature (70-80 degrees C), heating time (5-15 min) and the strength of the polymerized whey protein calcium induced gel are studied. The dissolution rate and the degree of hydrolysis in the artificial digestive juice. The experimental results show that the addition of calcium ions can effectively improve the gel strength of the polymerized whey protein. The stronger the polymerization degree of whey protein is, the greater the strength of the calcium induced gel is, the stronger the interaction between the molecules, and the more dense structure of the network structure. In artificial gastric juice, the dissolution rate of 4H in artificial gastric juice is less than 30%, and the dissolution rate of 4H in artificial small intestinal liquid can reach 100%.. The polymerization of whey protein is used to prepare microcapsules for bioactive substances, and it is applied to the symbiotic cow / goat milk yogurt, The experimental results are as follows: (1) the application of Ginsenoside in food is restricted by its color and bitterness. So the encapsulation of ginsenoside by polymeric whey protein can effectively cover its bitter taste and color. The encapsulation rate of the human ginseng saponin microcapsules prepared by the combination of polymeric whey protein and sharp hole coagulation bath can reach 97.15 + 1.95% in the mold. In the pseudo digestion experiment, the release rate of Ginsenoside in artificial gastric juice is about 20%, and it can be completely released in the artificial small intestine liquid. The ginsenoside microcapsule is used in the preparation of symbiotic yogurt. The results show that the sensory evaluation of ginsenoside microcapsule yogurt is significantly higher than that of the yogurt (1.6) (P0.01) which is directly added to ginsenoside (1.6). The addition of ginsenoside microcapsules significantly enhanced the water holding capacity of yogurt and increased the protein content of yogurt (P0.01). (2) probiotics were widely used in functional fermented dairy products, of which Lactobacillus acidophilus was poor in gastric acid tolerance, and polymerized whey protein based microcapsules could improve the survival rate of Lactobacillus acidophilus in digestive process. The experimental results of the encapsulation period of the microencapsulation rate of Lactobacillus acidophilus microcapsule of 92.90 + 3.90%. yoghurt prepared by the combination of polymeric whey protein and sharp hole coagulation bath showed that there was no significant difference in the content of probiotics in yogurt adding probiotic microcapsules compared with the control group, which proved that the microcapsules were stable in the storage period for up to 10 weeks. The bacteria in the microcapsules can be released by artificial intestinal fluid and the survival number can still reach 105cfu/m L. It shows that the edible yogurt with microcapsule of probiotics can ensure a large number of probiotics to colonize in the human intestine after digestion and play an important role in human health. (3) the film forming of the polymerized whey protein can be used. Microencapsulation of Lactobacillus acidophilus LA-5 and the preparation of probiotic microcapsule freeze-dried powder were made by freeze drying. The results showed that the hygroscopicity of the polymerized whey protein and the protection of Lactobacillus acidophilus LA-5 were not significantly different from that of dextrin. The experiment of the shelf life of the yoghurt for 10 weeks was carried out, and the results showed that the freeze-dried Lactobacillus acidophilus microorganism was microscoped. When the capsules are used in the preparation of yogurt, the bacteria can be fully released to make them multiply in the fermentation process to reach the ideal level. Meanwhile, it can be explained that the freezing drying process and the use of the polymeric whey protein base wall have no adverse effects on the proliferation and biological activity of the bacteria. The physicochemical properties of the polymerized whey protein prepared under the conditions were studied and characterized, and the feasibility and superiority of the gel properties in the field of microcapsule wall materials were studied. The theoretical basis for the encapsulation and application of a series of bioactive substances by the microcapsule wall material was provided. The saponins and Lactobacillus acidophilus microcapsules were prepared and applied to the fermented dairy products. The feasibility of polymeric whey protein used in microcapsule wall material was verified, and the theoretical basis and technical support for its application in the field of food industry were provided.

【学位授予单位】：吉林大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TS218;TS252.9

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