【作者】 张静；

【导师】 李元瑞； ROSENBERG Moshe；

【作者基本信息】 西北农林科技大学 ， 食品科学， 2012， 博士

【摘要】 本论文针对食品和医药行业中营养传递体系的两大载体—微胶囊和微球体进行研究。在微胶囊研究中,以小麦分离蛋白作为喷雾干燥微胶囊主要壁材,大豆油为芯材,分析壁材溶液与大豆油乳化后的乳浊液性质和干燥后的微胶囊性质,全面评价小麦分离蛋白作为喷雾干燥微胶囊壁材的性质和表现。在微球体研究中,以大豆分离蛋白溶液及其乳浊液、大豆分离蛋白与乳清分离蛋白混合溶液及其乳浊液为研究对象,通过外源式和内源式添加钙离子的方式,寻求适用于食品和医药行业的钙交联冷凝胶型微球体的制备方法,深入研究微球体性质,以期为相关研究提供基础指导和理论依据。在微胶囊研究中,旨在分析小麦分离蛋白作为喷雾干燥微胶囊壁材的性质。首先,将小麦分离蛋白溶液与三种淀粉糖混合后配制壁材溶液,分别为DE值5的麦芽糊精(MD5)、DE值15的麦芽糊精(MD15)和DE值24的玉米糖浆(CSS)。壁材溶液中固形物含量固定为20.0%(w/w),其中小麦蛋白含量为2.5%、5.0%和10.0%,相应的淀粉糖含量依次为17.5%、15.0%和10.0%;以大豆油为芯材,芯材添加量按照微胶囊中壁材:芯材(w/w)为75:25、50:50和25:75比率添加。壁材溶液与大豆油充分乳化后,分析乳浊液中油滴的粒径分布、平均粒径d3,2、比表面积和表面吸附量等性质。乳浊液经喷雾干燥获得微胶囊后,研究微胶囊的性质,如表层油脂、微胶囊化效率、芯材包埋率和微胶囊的内、外部结构等。结果表明,壁材中的蛋白质含量和淀粉糖的DE值,以及芯材的添加量都会影响乳浊液和微胶囊性质。喷雾干燥后得到直径在2～50μm之间的球体微胶囊,胶囊外部呈现出表面凹痕、凹痕中有小胶囊和皱缩等表面特征,胶囊内部为中空结构,芯材物质大豆油被蛋白壁膜包裹后嵌埋在由蛋白和淀粉糖组成的壁材中。以小麦分离蛋白与乳糖作为壁材物质,在同样条件下对大豆油进行微胶囊化处理。与淀粉糖相比,乳糖对乳浊液性质没有显著影响,但是因其对干燥和壁壳形成的影响,乳糖对微胶囊性质的影响较大,尤其是表层油脂、微胶囊化效率和胶囊的外部结构。乳糖在喷雾干燥后呈非定型的玻璃态,这种玻璃态是微胶囊表层油脂大幅减小、微胶囊化效率大幅增加的原因。在微球体研究中,首先以大豆分离蛋白溶液为试验材料,探讨适用于食品和医药行业的钙交联冷凝胶型微球体的制备方法。结果显示,蛋白含量为9.5%的大豆分离蛋白溶液,经充分热变性后迅速冷却,在50MPa压力下均质两次降低黏度后,分别与蛋白溶液质量10%和20%(w/w)的大豆油充分乳化后形成乳浊液,通过外源式和内源式添加钙离子的方法,能够获得大豆分离蛋白及其乳浊液的冷凝胶型微球体。其中,乳浊液中的蛋白质含量和油脂添加量均会影响外源式和内源式冷凝胶型微球体的蛋白质包埋率、油脂包埋率和溶解度。在外源式微球体的溶胀率试验中,微球体在pH为2.5和7.0的缓冲液中体积增加、发生膨胀,而在pH4.5缓冲液中体积减小、发生收缩。当缓冲液中含有钙离子时,在pH为2.5和7.0的缓冲液中,钙离子的存在减小了微球体的溶胀率;在pH为4.5的缓冲液中,钙离子的存在又减小了微球体的收缩率。将大豆分离蛋白(SPI)与乳清分离蛋白(WPI)以2:1、1:1和1:2(w/w)比率混合后,按照上述方法,制备混合蛋白溶液及其乳浊液的外源式和内源式钙交联冷凝胶型微球体。结果显示,除了蛋白含量和油脂添加量外,微球体性质还受到混合蛋白液中蛋白质比率的影响。乳清蛋白形成胶凝的速度快,且凝胶的连续性好,故含有乳清蛋白多的微球体,其包埋率较高,在水中的溶解度较小;但是由于乳清蛋白分子小于大豆蛋白分子,大豆蛋白变性后形成大的聚集体和三维结构能够为更多扩散进入的水分子提供空间,因此含有乳清蛋白较多的外源式微球体,其溶胀率较小。通过外源式和内源式钙交联法制备大豆分离蛋白溶液及其乳浊液、混合蛋白溶液及其乳浊液冷凝胶型微球体的方法有效可行。各微球体都呈现出良好的蛋白质包埋率和油脂包埋率,具有一定的水溶性,外源式微球体还具有较高的溶胀率。这些良好性质使得外源式和内源式微球体可以作为营养传递体系的载体,应用到相关食品、医药的研究和开发中。更多还原

【Abstract】 There are two parts in this dissertation mainly about the delivering device of nitrition delivery systems in food and pharmaceutical industry,one is about microencapsules based on wheat protein isolate(WHPI),the other is about microspheres based on soy protein isolate(SPI)and whey protein isolate(WPI)and their emulsions.The first part aimed to figure out the performance of WHPI as microcapsulating agent by spray drying,combined with maltodextrins(MDE5,MDE15)and corn syrup solid(DE 24,CSS)in wall system,while soy oil was encapsulated as core material.The total solid content in wall solution was 20%(w/w)in all cases with protein concentrations were 2.5%,5.0%and 10.0%,separately combined with three kinds of starch suger,with wall to core ratios(w/w)were 75:25,50:50 and 25:75 in dry capsules.The particle size distribution,mean particle size d3,2,specific surface area and surface excess in different emulsions were investigated,and the properties of dried microcapsules were discussed either,such as surface oil,microencapsulation efficiency,core retention and microstructure.Protein content in wall matrix,DE value of starch suger and oil load affected the properties of both emulsions and microcapsules.Microstructure by scanning electron microscopy stated the morphology of microcapsules was related to the protein-to-sugar ratio,DE value of starch suger and oil load at the same drying conditions.Microcapsules were spherical,with 2-50 μm in diameter,cental void,and oil droplets coated by protein film encapsulated in wall matrix.Then,WHPI was performed as microencapsulating agent by spray drying combined with lactose in wall system,while soy oil encapsulated as core material at indentical conditions mentioned above.Comparing with the three sorts of starch sugar,lactose did not display siginificant difference in emulsions but in microcapsules.Results emphasized that lastose was in grass phase after spray drying,which was the reason why surface oil and microencapsulation efficiency of capsules were dramatically bigger than those of the other microcapsules with starch suger in.All the conclusions illustrated that WHPI could be acceptable and used as wall material in microcapsulation by spray drying in related research and industry application.The second part was about microspheres.The methodology and some properties of coldset gelation microspheres by external and internal calcium cross-linked soy protein isolate(SPI)and related emulsions were investigated.9.5%SPI was autoclaved for pre-denaturation and then homogenized twice at 50MPa to decrease the visicosity first,then both external and internal calcium cross-linked cold-set microspheres attained from emulsified 9.5%SPI containing with 0,10%and 20%soy oil.Results showed the methodology was effective to achieve satisfing microspheres.Both protein and oil contents in emusions affected protein retention,oil retention and water solubility of external and internal microspheres.In swelling tests,external microspheres swelled in pH 7.0 and 2.5 buffers,while deswelled in pH 4.5 buffers.When togethered in buffers,calcium screened the charges on protein surface,reduced the electrostatic repulsion between amino acid residues,hence decreased either swelling or deswelling rates of microspheres in different buffers.The properties of microspheres by mixed proteins and related emulsions from SPI and WPI were investigated with same methodology,at different ratios(w/w)of SPI:WPI were 2:1,1:1 and 1:2.Results indicated that microspheres possessed satisfying properties just like microspheres from SPI only.More WPI in matrix gained higher retentions,lower water solubility and lower swelling rate than those with more SPI in.More WPI in microspheres gelled faster and produced gel with higher integrity,and that were the reasons for higher retentions and lower soluble protein content in buffers.Also,SPI formed into bigger aggregate and three-dimensional structure after denatured gelation,which could provide much more space for extra water to diffuse in during swelling,and that was why bigger swelling rates gained from microspheres based on more SPI and less WPI.Results indicated the methodology was effective and practicable to gain both external and internal calcium cross-linked cold-set microspheres from SPI,mixed proteins and related emulsions,most microspheres possessed satisfiying charactristics,like protein retention,oil retention,water solubility,external microspheres additionally owned good swelling rates,all of which means microspheres could be applied as delivering device as for nutrition delivery system in food and pharmaceutical development.更多还原