Designing Semipermeable Hydrogel Shells with Controlled Thickness through Internal Osmosis in Triple-Emulsion Droplets

Hydrogel shells that compartmentalize the water core from the aqueous surrounding provide molecular selectivity on size and charge in transmembrane transport. It is highly demanding to produce thin hydrogel shells to minimize diffusion length and maximize core volume. Here, internal osmosis in water-in-oil-in-water-in-oil (W/O/W/O) triple-emulsion droplets is used to produce thin hydrogel shells enclosing a large water core. The triple-emulsion droplets are prepared to have an ultrathin middle oil layer using a capillary microfluidic device. The innermost water droplet has a higher osmolarity than the outer water layer containing photopolymerizable hydrogel precursors, which pumps water from the outer layer to the core through the ultrathin oil layer by the osmosis. Therefore, the outer layer gets thinner and hydrogel precursors are enriched while the size of the triple-emulsion droplets remains unchanged. Through photopolymerization of precursors and phase transfer from oil to water, hydrogel shells enclosing water core are produced in the water environment; the oil layer is ruptured for molecular exchange through the shells. The thickness and composition of the hydrogel shells are precisely controllable by the osmotic conditions. The shells show a high permeation rate due to the thinness as well as controlled cut-off threshold of permeation for neutral and charged molecules.     

油茶籽油的脂肪酸成分分析及其微胶囊化的制备

通过气相色谱-质谱法(GC-MS),对油茶籽油的脂肪酸成分进行分析,油茶籽油中主要的脂肪酸成分为棕榈酸、硬脂酸、油酸、亚油酸和亚麻酸等,其中不饱和脂肪酸成分达80%以上。以大豆分离蛋白和麦芽糊精作为壁材,采用喷雾干燥的方式对油茶籽油进行微胶囊化制备研究。通过单因素和正交实验,考察了乳化温度、复合壁材配比、壁材浓度以及壁芯材配比等因素对微胶囊包埋率的影响,优化出油茶籽油微胶囊制备的最佳工艺条件为:乳化温度为75℃,大豆分离蛋白和麦芽糊精的配比为0.6,壁材浓度为13%,壁芯材比例为1.5:1。在上述条件下,制备的油茶籽油微胶囊的包埋率达83.83%。对油茶籽油微胶囊化产品进行相关检测和分析。扫描电镜(SEM)显示微胶囊化产品结构完整,具有较好的包埋效果。微胶囊的粒径通过马尔文激光粒度仪测定为8.43μm。     

Microencapsulation of camellia oil to maintain thermal and oxidative stability with focus on protective mechanism

Camellia oil (CO) microcapsules were developed using chitosan–soybean protein isolate (CS-SPI) complexes as wall materials and transglutaminase (TGase) as the cross-linking agent. Results indicated that CO/SPI under the ratio of 1:2 exhibited the highest microencapsulation efficiency and yield, possessing the best encapsulation effect. Morphology observation showed that CO microcapsules were intact, compact and nearly spherical. The microencapsulated CO exhibited the improved thermal resistance and significantly lower peroxide values after 3 days storage, demonstrating that the produced microcapsule was a promising way to maintain the thermal and oxidative stability of camellia oil. It could be found evidence from FTIR, which indicated that covalent cross-linking and hydrogen bonding might be involved among wall materials, and physical interactions between the core and wall materials. Therefore, the produced CO microcapsules could be an effective way to protect camellia oil, which was helpful for improving the processing and storage qualities of camellia oil.     

Application of starch microcapsules containing essential oil in food preservation

Abstract

Consumers' pursuit to a healthy lifestyle has promoted people to develop new technologies that can prolong the shelf life of food without the use of preservatives. Compared with other types of preservation, edible microcapsules containing essential oils (EOs) are becoming more and more popular especially the starch microcapsules containing essential oil (EOs-starch microcapsules) because of their environmentally friendly, healthier characteristics and the ability to carry active ingredients. In addition, the EOs-starch microcapsules can also reduce the flavor influence and prolong the action time of essential oil on food through its slow release effect, which can promote the use of EOs in food. Understanding the different collocation of edible starch microcapsules and EOs and the related antibacterial mechanism will be more effective and targeted to promote the application of EOs in the real food system. The review focus on the contribution of EOs-starch microcapsules to prolong the shelf life of food products, (1) binding characteristics of EOs-starch microcapsules were analyzed, (2) systematically summarizing the main materials and methods for preparing the EOs-microcapsules, (3) specifically addressing the action mechanisms of EOs-starch microcapsules on microorganism, (4) discussing the applications of EOs-starch microcapsules in specific food.     

Antimicrobial functionalization of Ca alginate-coconut oil latent heat storing microcapsules by Ag nanoparticles

Latent heat storage by phase change materials (PCM) is a promising way of thermal energy storage for equilibrating the daily fluctuation of temperature in office- and home buildings. Bio-originated compounds have got great importance to evade further plastic contamination all over the world. Durability of biodegradable natural materials by means of environmentally friendly agents is an exciting challenge. In this study Ca alginate-coconut oil eco-friendly core-shell PCM microcapsules were functionalized with Ag nanoparticles, following their synthesis using harmless reducing agents. Throughout the preparation of the PCM microcapsules by repeated interfacial coacervation/crosslinking procedure, the Ag nanoparticles were homogeneously dispersed in the Ca alginate shell. High coconut oil content was achieved in the Ag nanoparticle-loaded microcapsules, which was not influenced by the Ag nanoparticle content. The high PCM content resulted in correspondingly high latent heat storing capability. The freezing and melting heat storing capacities were in the range of 83.6 and 85.6 J/g, as well as 89.7 to 92.6 J/g, respectively, matching to the extremely high PCM content in the range of 82.7% to 84.8% (m/m). Leaking of the heat storing microcapsules was not observed after 200 heating-cooling cycles. The Ag nanoparticle content did not influence the PCM ratio of the microcapsules, although as expected their antimicrobial potential was significantly enhanced by it. The highest Ag nanoparticle loading, that was 1.3% (m/m) related to the total mass of microcapsules, exerted excellent antibacterial and antifungal impact.     

Multifunctional phase change microcapsules based on graphene oxide Pickering emulsion for photothermal energy conversion and superhydrophobicity

In order to enlarge the applications of microencapsulated phase change materials (microPCMs), the novel stearic acid (SA)@graphene oxide (GO)/melamine-formaldehyde (MF) multifunctional superhydrophobic microPCMs were prepared with the method of condensation polymerization. We have made a systematical study of the effects of GO content on the SA@GO/MF microPCMs. The morphology and chemical composition characterizations showed the successful fabrication of microcapsules. The differential scanning calorimeter (DSC) identified that microPCMs could store latent heat energy. According to the contact angles (CA) measurement, the microPCMs displayed the water contact angle of 160.2°, which possessed the superhydrophobic property. Moreover, the self-cleaning property of SA@GO/MF microPCMs was demonstrated by designing self-cleaning experiment. The simulated irradiation experiment showed the good photothermal conversion performance of microPCMs. Owing to photothermal energy conversion performance and superhydrophobicity, multifunctional phase change microcapsules could have vital potentials in energy conversion and self-cleaning.     

壳聚糖包裹广藿香精油微胶囊的制备及表征

采用复合凝聚法,以广藿香精油为芯材,壳聚糖（CTS）和阿拉伯胶（GA）为壁材,制备了广藿香精油微胶囊。采用扫描电子显微镜（SEM）、激光粒度仪、傅里叶红外光谱（FT-IR）等对微胶囊进行表征。结果表明,当乳化剂用量为质量分数1%,芯壁质量比为1∶2,乳化转速为2 500r/min,复凝pH为5,固化剂用量为1.5g时,微胶囊包封率和载药量最佳,微胶囊球形规则、分散性好,平均粒径为10.5μm。     

广藿香油微胶囊化学交联法对棉织物的功能整理

以2D树脂作交联剂,以广藿香油微胶囊对棉织物进行防皱抗菌功能整理。运用扫描电镜及红外光谱对织物进行表征,并对织物抑菌耐水洗性能、缓释性能、防皱性能及甲醛含量进行了测试。结果表明,微胶囊通过2D树脂的桥梁连接作用被固着在棉织物上,提高了微胶囊织物防皱抗菌耐洗涤效果。