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。     

复凝聚法制备石蜡相变储能微胶囊及其性能研究

以壳聚糖和阿拉伯胶为壁材,石蜡为芯材,采用复凝聚法制备相变储能微胶囊。通过单因素实验,探究pH、复凝聚反应时间、芯壳比、交联剂用量等对微胶囊包覆率及包覆效率的影响。使用扫描电子显微镜、傅里叶红外光谱仪、差示扫描量热仪和热重分析仪对微胶囊的形貌、化学组成及热性能进行研究。结果表明,在最优工艺条件下(pH=4.5,复凝聚反应时间20 min,芯壳比1.5∶1,交联剂用量2 m L)制备出的微胶囊粒径20³0μm之间,包覆率为52.84%,包覆效率为56.27%。壳聚糖/阿拉伯胶壁材对石蜡起到保护作用,使其耐热性提高。     

复凝聚法制备石蜡相变储能微胶囊及其性能研究

以壳聚糖和阿拉伯胶为壁材,石蜡为芯材,采用复凝聚法制备相变储能微胶囊。通过单因素实验,探究pH、复凝聚反应时间、芯壳比、交联剂用量等对微胶囊包覆率及包覆效率的影响。使用扫描电子显微镜、傅里叶红外光谱仪、差示扫描量热仪和热重分析仪对微胶囊的形貌、化学组成及热性能进行研究。结果表明,在最优工艺条件下(pH=4.5,复凝聚反应时间20 min,芯壳比1.5∶1,交联剂用量2 m L)制备出的微胶囊粒径20~30μm之间,包覆率为52.84%,包覆效率为56.27%。壳聚糖/阿拉伯胶壁材对石蜡起到保护作用,使其耐热性提高。     

微胶囊的制备方法研究进展

本文介绍了微胶囊的常用天然壁材和微胶囊的制备方法。天然壁材分为碳水化合物、蛋白质和脂类3大类,其中传统天然壁材有海藻酸钠、壳聚糖、明胶等,新型天然壁材包括脂质体、微生物细胞壁(酵母菌细胞壁)、多孔淀粉等。微胶囊的常规制备方法包括:复凝聚法、单凝聚法、界面聚合法、原位聚合法、锐孔-凝固浴法、喷雾干燥法等,微胶囊的新型制备方法有:分子包埋法、微通道乳化法、超临界流体快速膨胀法、酵母微胶囊法、层-层自组装法、模板法等。但是微胶囊技术还存在诸多不成熟之处,有些关键问题还有待解决。     

磺化碱木质素聚氧乙烯醚/聚乙烯亚胺静电自组装法制备阿维菌素微胶囊

以磺化碱木质素聚氧乙烯醚（SAL-PEG）/聚乙烯亚胺（PEI）为壁材,阿维菌素原药为芯材,采用静电自组装法制备了木质素基阿维菌素微胶囊（AVM-CS）。分别研究芯壁比、交联剂的用量、交联反应pH、NaCl溶液浓度等因素对微胶囊成囊性能和缓释性能的影响,确定优化的AVM-CS成囊参数为：芯壁比=2/5、戊二醛用量=2%、交联pH=8,在1 mol/L NaCl溶液中成囊。制备的AVM-CS呈不规则球状,粒径范围为1~5μm。缓释性能研究发现AVM-CS与聚氨酯壁材制备的阿维菌素微胶囊的缓释效果相当,但是AVM-CS的释放比较完全,原药的利用率更高。     

含壳聚糖-V_E微胶囊化妆品中V_E的稳定性

以壳聚糖为壁材、VE为芯材采用单凝聚法制备壳聚糖-VE微胶囊,然后分别制备VE化妆品和壳聚糖-VE微胶囊化妆品。以正己烷为溶剂萃取放置一定时间化妆品中VE,采用HPLC测定萃取VE含量,对比分析不同化妆品中VE稳定性。实验得出:壳聚糖-VE微胶囊化妆品与直接加入VE化妆品比较,15d后直接加入VE化妆品中的VE含量下降22.3%,壳聚糖-VE微胶囊化妆品中的VE含量下降8.7%,壳聚糖-VE微胶囊化妆品中的VE得到保护和隔离,提高了化妆品中VE稳定性。     

壳聚糖/三元共聚物微胶囊的制备及表征

利用多聚电解质间的凝聚作用,在细胞生理条件下制备了一种液核带正电的新型微胶囊体系.该微胶囊的液核为N-乙酰化率50%的壳聚糖衍生物（HNC) 溶液,壳膜由HNC与异丁烯酸 (MAA)-羟乙基异丁烯 (HEMA)-甲基丙烯酸甲酯 (MMA) 三元共聚物(MAA-HEMA-MMA)凝聚而成.从N-乙酰化率15.3%的市售壳聚糖（FNC）出发,乙酰化制备的HNC在细胞生理pH条件下具有良好的溶解特性和质子化率.黏度80～3000 cPa•s间的HNC溶液可制备外观整齐、尺度均一的球形微胶囊.HNC分子量及浓度、pH、凝聚时间等对微胶囊的壳膜结构和表面特性都有一定影响,并进一步影响微胶囊的渗透性和强度.高浓度HNC有利于制备高强度的微胶囊,而低浓度HNC则有利于制备渗透性较好的微胶囊.     

牛至精油微胶囊抑菌效果研究

选用明胶、阿拉伯胶为壁材,采用复凝聚法制备了明胶/阿拉伯胶牛至精油微胶囊,研究该微胶囊对大肠杆菌、金黄色葡萄球菌、番茄灰霉菌、番茄早疫菌的抑制效果。结果表明,牛至精油微胶囊的包埋率为80.34%,产率为83.69%,牛至精油经微胶囊化后对四种供试菌株的抑制效果更加持久。     

牛至精油微胶囊抑菌效果研究

选用明胶、阿拉伯胶为壁材,采用复凝聚法制备了明胶/阿拉伯胶牛至精油微胶囊,研究该微胶囊对大肠杆菌、金黄色葡萄球菌、番茄灰霉菌、番茄早疫菌的抑制效果。结果表明,牛至精油微胶囊的包埋率为80.34%,产率为83.69%,牛至精油经微胶囊化后对四种供试菌株的抑制效果更加持久。     

氧指示剂在香料微胶囊壁材筛选中的应用

以海藻酸钠（SA）、甲基纤维素（MC）、羧甲基壳聚糖（CMC）作为微胶囊壁材，亚甲基蓝（MB）/TiO2/甘油（Gly）作为氧指示剂，制备了6种微胶囊氧指示剂复合薄膜。根据氧指示剂复合薄膜激活、回色以及重复利用性筛选合适的屏氧壁材体系。当MC的质量浓度为20 g/L，MB、TiO2、Gly用量分别为0.05 g、1 g和0.5 mL时，MB/TiO2/Gly/MC氧指示剂复合薄膜光催化激活效率最佳。在空气湿度为75%、温度为35 ℃条件下，MC/SA/MC和MC/CMC/SA氧指示剂复合薄膜在10 h的回色率分别为28.7%和27.9%，且回色时变化较均匀；重复使用3次，MC/SA/MC和MC/CMC/SA氧指示剂复合薄膜的回色率仅分别下降了0.8%和1.0%，说明这两种壁材体系是屏氧良好的香料壁材。将这两种壁材体系通过喷雾干燥法包埋玫瑰精油芯材制备香料微胶囊，存放7 d后，包埋在MC/CMC/SA中的芯材有新物质出现而MC/SA/MC中无新物质，说明MC/SA/MC体系对精油有更好的保护作用。     

Optimization of cinnamaldehyde microcapsule wall materials by experimental and quantitative methods

Microencapsulation is a widely-investigated technique used for the unstable material preservation since the wall materials prevent the core materials from loss and deterioration. To improve the stability of cinnamaldehyde (CAL), different microcapsule wall systems are fabricated by spray-drying, and then characterized by experimental methods to determine the most suitable wall materials. Surface morphology, encapsulation efficiency, effective loading capacity, as well as moisture absorption property are evaluated, and the results suggest that a three-matrix system of methyl cellulose (MC)/sodium alginate (SA)/MC or MC/carboxymethyl chitosan (CMC)/SA wall formulation is more suitable for CAL microencapsulation. Moreover, a novel quantitative method is also proposed to verify the most stable wall material microencapsulation. The quantitative results show that the highest activation energy (53.00 ± 2.24 kJ/mol) is observed for the MC/CMC/SA-encapsulated CAL microcapsule. Taken together, the results suggest that MC/CMC/SA wall formulation shows excellent barrier properties and is superior to other wall materials in preventing microencapsulated CAL deterioration. This study will be efficient in designing an ideal capsule for CAL microencapsulation.     

Microencapsulation of tea tree oil by spray‐drying with methyl cellulose as the emulsifier and wall material together with chitosan/alginate

Amphiphilic methyl cellulose (MC) was used as the emulsifier and the internal wall material to increase the microencapsulation efficiency (ME) of tea tree oil (TTO) and the stability of the emulsion for spray‐drying. The results of microscopy images, zeta potential, and microencapsulation efficiency indicated that the wall material components affected the morphology, stability, and ME of the microcapsules. The microcapsules with the wall materials of MC/chitosan (CTS)/alginate (ALG) were spherical and had higher ME than those with monocomponent or bicomponents of MC, CTS, or ALG, or triple components of MC/ALG/CTS. Spray drying conditions were optimized to find the optimum microencapsulation conditions. The highest ME 89.4% and the highest oil embedding rate (ER) 90.4% were obtained through spray‐dying the emulsion of 0.8 mL TTO embraced by 0.4 g MC, 0.6 g CTS, and 3 g ALG at the drying conditions of inlet air temperature 210 °C, needling frequency 2 s, and pump flow rate 55 r/min. Microencapsulation obviously decreased the release of TTO. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44662.     

Microencapsulation of capsanthin by soybean protein isolate‐chitosan coacervation and microcapsule stability evaluation

Although capsanthin possesses excellent coloring performance and healthcare functions, its application in the food industry is limited due to its susceptibility to humidity, heat, and light. The purpose of this research was to microencapsulate capsanthin by soybean protein isolate (SPI)‐chitosan coacervation and evaluate whether the microencapsulation improved the stability of capsanthin against the adverse conditions mentioned above. The results indicated that the optimum conditions for capsanthin microencapsulation were emulsification speed 10,000 rpm, emulsification temperature 45°C, wall concentration 15 g/L and core to wall ratio 1:2 (w/w). Under these conditions, the droplets in the emulsion were even in size distribution without agglomeration and the microencapsulation efficiency and microencapsulation yield reached 90.46% and 86.69%, respectively. Microencapsulation increased the stability of capsanthin against low/medium moisture, heat, and especially light, but was less effective in protecting capsanthin microcapsules in high moisture. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39671.     

Effect of Homogenization Pressure and Oil Load on the Emulsion Properties and the Oil Retention of Microencapsulated Basil Essential Oil (Ocimum basilicum L.)

The objective of this work was to evaluate the influence of oil concentration and homogenization pressure on the emulsion and particle properties during the microencapsulation of basil essential oil by spray drying, using gum arabic as the wall material. Experiments were planned according a 2² rotational central composite design. The independent variables were oil concentration with respect to total solids (10–25%) and homogenization pressure (0–100 MPa). Emulsions were analyzed for droplet mean diameter, stability, and viscosity, and particles were analyzed for oil retention, moisture content, particle size, and morphology. Emulsion viscosity was not affected by any of the independent variables. The increase in the homogenization pressure from 0 to 100 MPa resulted in smaller emulsion droplet size (down to 0.40 µm) and, consequently, higher oil retention (up to 95%). On the other hand, higher oil loads (25%) resulted in poorer oil retention (51.22%). Microencapsulation of basil essential oil using gum arabic as the wall material proved to be a suitable process to obtain powdered basil essential oil, presenting great oil retention with the use of lower oil concentration and higher homogenization pressure.     

Encapsulation Efficiency of Food Flavours and Oils during Spray Drying

Microencapsulation is a rapidly expanding technology which is a unique way to package materials in the form of micro- and nano-particles, and has been well developed and accepted within the pharmaceutical, chemical, food and many other industries. Spray drying is the most commonly used encapsulation technique for food products. A successful spray drying encapsulation relies on achieving high retention of the core materials especially volatiles and minimum amounts of the surface oil on the powder particles for both volatiles and non-volatiles during the process and storage. The properties of wall and core materials and the prepared emulsion along with the drying process conditions will influence the efficiency and retention of core compounds. This review highlights the new developments in spray drying microencapsulation of food oils and flavours with an emphasis on the encapsulation efficiency during the process and different factors which can affect the efficiency of spray drying encapsulation.     

Microencapsulation of Cinnamon Oleoresin by Spray Drying Using Different Wall Materials

Microencapsulation of spice oleoresin is a proven technology to provide protection against degradation of sensitive components present therein. The present work reports on the microencapsulation of cinnamon oleoresin by spray drying using binary and ternary blends of gum arabic, maltodextrin, and modified starch as wall materials. The microcapsules were evaluated for the content and stability of volatiles, entrapped and total cinnamaldehyde content for six weeks. A 4:1:1 blend of gum arabic:maltodextrin:modified starch offered a protection, better than gum arabic as seen from the t_1/2; i.e., time required for a constituent to reduce to 50% of its initial value.     

Mixture Design Approach in Wall Material Selection and Evaluation of Ultrasonic Emulsification in Flaxseed Oil Microencapsulation

Flaxseed oil, sensitive to oxidation, was systematically microencapsulated with six triple wall materials combinations [carbohydrate (maltodextrine and two different modified starches (N-Lok® and HiCap® 100)); protein (sodium caseinate, whey protein concentrate); and Arabic gum] for the highest microencapsulation efficiency and oxidation stability. Proportions of the triple wall materials were optimized in mixture design using the quadratic model. Effects of Ultra-Turrax and ultrasonic emulsifications on microencapsulation efficiencies were additionally characterized in the optimized wall material combinations. The microcapsules produced were investigated for particle size distribution, moisture content, water activity, bulk density, and oxidative stability. Results showed that the combination of modified starch (Hi-Cap® 100)/Arabic gum/whey protein concentrate (4/0/1, w/w/w) provided the highest efficiency in flaxseed oil microencapsulation. However, the only successful combination in preventing flaxseed oil oxidation was maltodextrine/Arabic gum/whey protein concentrate (4/0/1, w/w/w). The microcapsules produced by ultrasonic emulsification had higher microencapsulation efficiency than that of Ultra-Turrax emulsification.     

Microencapsulation of Cinnamon Oleoresin by Spray Drying Using Different Wall Materials

Microencapsulation of spice oleoresin is a proven technology to provide protection against degradation of sensitive components present therein. The present work reports on the microencapsulation of cinnamon oleoresin by spray drying using binary and ternary blends of gum arabic, maltodextrin, and modified starch as wall materials. The microcapsules were evaluated for the content and stability of volatiles, entrapped and total cinnamaldehyde content for six weeks. A 4:1:1 blend of gum arabic:maltodextrin:modified starch offered a protection, better than gum arabic as seen from the t_1/2; i.e., time required for a constituent to reduce to 50% of its initial value.     

Properties and Stability of Spray-Dried and Freeze-Dried Microcapsules Co-Encapsulated with Fish Oil,Phytosterol Esters,and Limonene

The objectives of this study were to investigate the properties and stability of microcapsules containing fish oil co-encapsulated with phytosterol ester and limonene, prepared by spray-drying and freeze-drying methods. Whey protein isolate and soluble corn fiber were used as wall materials in the encapsulation process. The properties of microcapsules, including structure, glass transition, volatile/non-volatiles retention, microencapsulation efficiency, oxidation stability, color measurement, and sensory profiles, were evaluated after drying and during a seven-day accelerated storage trial. The finding reveals that drying methods have an effect on the retention of volatile fraction and the physical structure of the wall matrix consisted of WPI and SCF, consequently influencing the storage stability of the powders. Significantly higher retention of volatile fraction (p < 0.05) and lower surface oil were found in the spray-dried samples, resulting in the higher microencapsulation efficiency. However, samples dehydrated by both methods have good redispersion properties, showing no statistical significance (p > 0.05). The oxidation of the encapsulated oils was comparable for both spray- and freeze-dried samples during the seven-day accelerated storage trial but the loss of limonene flavor was significantly higher in the freeze-dried samples (p < 0.05). Sensory evaluation indicated that the addition of limonene could mask the unpleasant fishy odor in the co-encapsulated microcapsules. Overall, freeze drying did not produce powders with superior properties and did not show better protection towards the core materials than spray drying.     

Factors Influencing the Antibacterial Activity of Chitosan and Chitosan Modified by Functionalization

The biomedical and therapeutic importance of chitosan and chitosan derivatives is the subject of interdisciplinary research. In this analysis, we intended to consolidate some of the recent discoveries regarding the potential of chitosan and its derivatives to be used for biomedical and other purposes. Why chitosan? Because chitosan is a natural biopolymer that can be obtained from one of the most abundant polysaccharides in nature, which is chitin. Compared to other biopolymers, chitosan presents some advantages, such as accessibility, biocompatibility, biodegradability, and no toxicity, expressing significant antibacterial potential. In addition, through chemical processes, a high number of chitosan derivatives can be obtained with many possibilities for use. The presence of several types of functional groups in the structure of the polymer and the fact that it has cationic properties are determinant for the increased reactive properties of chitosan. We analyzed the intrinsic properties of chitosan in relation to its source: the molecular mass, the degree of deacetylation, and polymerization. We also studied the most important extrinsic factors responsible for different properties of chitosan, such as the type of bacteria on which chitosan is active. In addition, some chitosan derivatives obtained by functionalization and some complexes formed by chitosan with various metallic ions were studied. The present research can be extended in order to analyze many other factors than those mentioned. Further in this paper were discussed the most important factors that influence the antibacterial effect of chitosan and its derivatives. The aim was to demonstrate that the bactericidal effect of chitosan depends on a number of very complex factors, their knowledge being essential to explain the role of each of them for the bactericidal activity of this biopolymer.