微胶囊化法改善膨胀型阻燃剂与聚丙烯的相容性

为了增强多聚磷酸铵(APP)-季戊四醇(PT)-三聚氰胺(M)组成的膨胀型阻燃剂(IFR)与聚丙烯(PP)的相容性，选用RY界面接枝剂，一端含有能与活泼H反应的基团，与IFR颗粒表面的-NH-，-OH基团反应，另一端含有与底材相容性好的油性基团，通过表面接枝的方法，将IFR微胶囊化。SEM和流变性实验证明该技术增强了阻燃剂与PP的相容性。     

Characteristics of microcapsule of red ginger (Zingiber officinale var. Rubrum) essential oil produced from different Arabic gum ratios on antimicrobial activity toward Escherichia coli and Staphylococcus aureus

Essential oil has antimicrobial activity. Encapsulation of essential oil might affect its antimicrobial activity. The present study was aimed to study the characteristic of red ginger essential oil microcapsule obtained from varying Arabic gum ratios on the growth inhibition of E. coli dan S. aureus. Red ginger essential oil from steam distillation was coated using Arabic gum with ratio 1:3, 1:4, 1:5 (w/b). The 1:3 (v/w) ratio of red ginger essential oil and Arabic gum showed the best microcapsule characteristics with average inhibition diameter zones 5.67 mm for E. coli and 6.67 mm for S. aureus, and reduction of bacterial count for E. coli 1.8 log CFU/g and S. aureus 2.3 log CFU/g, yield of microcapsule 51.54%, water activity 0.207, water content 3.57%, solubility 97.46%, surface oil 0.08%, and particle size 258.2 µm. The major component of red ginger essential oil was ar-curcumene, zingiberen, β-bisabolene, β-sesquiphellandrene, and camphene.     

Advances in micro and nano-encapsulation of bioactive compounds using biopolymer and lipid-based transporters

BackgroundBioactive compounds possess plenty of health benefits, but they are chemically unstable and susceptible to oxidative degradation. The application of pure bioactive compounds is also very limited in food and drug formulations due to their fast release, low solubility, and poor bioavailability. Encapsulation can preserve the bioactive compounds from environmental stresses, improve physicochemical functionalities, and enhance their health-promoting and anti-disease activities.Scope and approachMicro and nano-encapsulation based techniques and systems have great importance in food and pharmaceutical industries. This review highlights the recent advances in micro and nano-encapsulation of bioactive compounds. We comprehensively discussed the importance of encapsulation, the application of biopolymer-based carrier agents and lipid-based transporters with their functionalities, suitability of encapsulation techniques in micro and nano-encapsulation, as well as different forms of improved and novel micro and nano-encapsulate systems.Key findings and conclusionsBoth micro and nano-encapsulation have an extensive application, but nano-encapsulation can be a promising approach for encapsulation purposes. Maltodextrin in combination with gums or other polysaccharides or proteins can offer an advantageous formulation for the encapsulation of bioactive compounds by using encapsulation techniques. Electro-spinning and electro-spraying are promising technologies in micro and nano-encapsulation, while solid lipid nanoparticles and nanostructure lipid carriers are exposing themselves as the promising and new generation of lipid nano-carriers for bioactive compounds. Moreover, phytosome, nano-hydrogel, and nano-fiber are also efficient and novel nano-vehicles for bioactive compounds. Further studies are required for the improvement of existing encapsulate systems and exploring their application in food and gastrointestinal systems for industrial application.     

Improvement of the stability of nattokinase using γ-polyglutamic acid as a coating material for microencapsulation

In this study, nattokinase (NK) was microencapsulated in high-molecular-weight Na-γ-PGA, and the amount of NK added to the Na-γ-PGA was in the ratio of 1:1 and 2:1 w/w, which was designated as NK-100 and NK-200, respectively. The temperature and pH stability of microencapsulated NK were found to be higher than those of the free form. Free NK lost its overall initial activity after treatment at a temperature above 60 °C or at a pH less than 5.0 for 1 h. NK-100 and NK-200 retained 35% and 60% of their activities after exposure to an acidic condition of pH 4.0 and possessed 18% and 25% activity after treatment at 60 °C for 1 h, respectively. Furthermore, NK-100 and NK-200 exhibited more protective bioactivity than free NK did in storage stability tests. This simple and versatile approach can be potentially applied to the microencapsulation of various biomolecules for drug-delivery applications.     

Role of glycated caseinate in stabilisation of microencapsulated lipophilic functional ingredients

The aim of the present study was to investigate the possible impact of the antioxidative activity and the altered technological properties of glycated caseinate on the oxidative stability of microencapsulated fish oil. Glucose, glucose syrup or dextrans were used for glycation of caseinate and the resulting blends were intensively characterised prior to their use for microencapsulation. After microencapsulation, hydroperoxide and propanal content of the encapsulated fish oil was monitored over a period of up to eight weeks.     

Evaluation of lipid oxidation in spaghetti pasta enriched with long chain n−3 polyunsaturated fatty acids under different storage conditions

This study investigated lipid oxidation in spaghetti enriched in long chain n−3 polyunsaturated fatty acids (LC n−3 PUFA) by the addition to semolina of an integrator containing eicosapentaenoic acid and docosahexaenoic acid. Two oxidative parameters were evaluated: peroxide value (PV), to assess primary oxidation and oxidised fatty acids to quantify secondary oxidation products. Functional spaghetti had a shelf life comparable to control pasta. LC n−3 PUFA were not significantly implicated in the onset of oxidation in spaghetti stored under daylight and accelerated oxidation in a laboratory heater. Storage decidedly affected shelf life: PV in functional spaghetti increased from 7.1 to 43.4 meq O₂/kg of fat under light exposure over 12 months, and from 7.1 to 16.2 meq O₂/kg under accelerated ageing at 55 °C for 27 days, reproducing about 18 months at room temperature. Oxidised fatty acids increased in fortified spaghetti from 4.8 to 13.8 g/100 g of fat under light exposure over 12 months and from 4.8 to 7.8 g/100 g of fat at 55 °C in 27 days. The high sensitivity of spectrophotometric and chromatographic analytical methods permitted the evaluation of primary and secondary oxidative derivatives in small amounts of fat.     

Preparation of microencapsulated carbon microspheres coated by magnesium hydroxide/polyethylene terephthalate flame–retardant functional fibers and its flame retardant properties

In order to improve the compatibility between the flame retardants of carbon microspheres coated by magnesium hydroxide (MH@CMSs) and the PET matrix and improve the spinnability of the masterbatch, MH@CMSs have been microencapsulated by PET to obtain microencapsulated carbon microspheres coated by magnesium hydroxide flame retardants – MMH@CMSs.Morphologies and structures of MMH@CMSs have been studied by scanning electron microscope (SEM), transmission electron microscopy (TEM), and FTIR, which showed that an organic shell layer of PET as capsule wall was coated on the surface of MH@CMSs. A series of MMH@CMSs/PET fibers with different MMH@CMSs contents were successfully prepared through the melt-spinning method. The morphology and structure of MMH@CMSs/PET fibers were characterized by SEM and FTIR. The flame retardancy of MMH@CMSs/PET fibers was determined via limiting oxygen index (LOI) test and cone calorimeter. Results showed that the MMH@CMSs/PET fibers possessed optimum flame retardancy when the MMH@CMSs content is 0.6 wt.%, at which the LOI reached a maximum of 25.8, and the pk-HRR, total heat release, and total smoke release were reduced by 27.4, 20, and 13.6%, compared with pure PET fibers, respectively. Moreover, the flame-retardant mechanism was studied by thermogravimetric analysis, thermogravimetric analysis-infrared spectrometry, and the SEM of the residue char, which disclosed that MMH@CMSs enhanced the thermal stability of PET fibers, and promoted PET fibers to form a dense and continuous protective char layer that effectively blocked heat transfer and combustible gas release.     

Aqueous Preparation and Evaluation of Albumin‐Chitosan Microspheres Containing Indomethacin

Controlled‐release egg albumin‐chitosan microspheres containing indomethacin as a model drug were successfully prepared by coacervation method. The proposed method can offer a simple method for microsphere preparation in an aqueous system with the elimination of the use of organic solvents that are usually needed in conventional techniques of microencapsulation. The interaction between negatively charged egg albumin molecules in phosphate buffer, pH 7.2, or sodium hydroxide solution and positively charged chitosan molecules dissolved in diluted acetic acid to form an insoluble precipitate was the principle for the formation of the microspheres. The effects of many process variables, such as amount of formaldehyde as a cross‐linking agent, stirring time, final pH of encapsulation medium, initial drug loading, and albumin concentration or albumin‐to‐chitosan weight ratio, on the properties of the prepared microspheres were investigated. Incorporation efficiencies of the microspheres to the drug were high in most cases and ranged between 63.3 ± 3.6% and 92.39 ± 3.2%, while particle sizes were 435.2 ± 12.6 up to 693.9 ± 34.6 µm for the different tested batches. On the other hand, the values of angles of repose and compressibility indices were in the range of 23.5 ± 0.4 to 32.0 ± 0.7 degrees and 11.1 ± 0.7% to 23.6 ± 0.7% respectively, which indicate overall good free flowing nature of the microspheres of all batches. The maximum required amount of the cross‐linking agent was determined to avoid excessive unnecessary chemicals. It was also noticed that excessive time of stirring and excessive initial drug loading are not recommended as it may lead to microspheres of low properties. The pH of the encapsulation media (pH 3.77 up to pH 4.91) significantly affected the properties of the microspheres. As the pH of the encapsulation media was increased, the incorporation efficiency, particle size, and flowability decreased, along with increase of drug release rate, which could be related to incomplete cross linking of the microspheres matrix. It was also observed that high concentration of albumin solution and accordingly the increase of albumin‐to‐chitosan weight ratio were accompanied with increases in incorporation efficiency and particle size with improved microsphere flowability and slow indomethacin release. Thus, the proposed microspheres showed the ability to control the release of indomethacin, and their properties were highly affected by many process variables that could be controlled to obtain an optimized system.     

Preparation and characterization of microencapsulated polythiol

Microcapsules containing curing agent for epoxy were successfully prepared by in situ polymerization with poly(melamine–formaldehyde) (PMF) as the shell material and high-activity polythiol (pentaerythritol tetrakis (3-mercaptopropionate), PETMP) as the core substance. Having been encapsulated, the core material PETMP had the same activity as its raw version. The synthesis approach was so improved that the consumption of polythiol was reduced to a low level. By carefully analyzing the influencing factors including catalyst concentration, reaction time, reaction temperature, feeding weight ratio of core/shell monomers, dispersion rate and emulsifier content, the optimum synthetic conditions were found out. The results indicated that not only core content and size of the microcapsules but also thickness and strength of the shell wall can be readily adjusted by the proposed technical route. The relatively thin shell wall (0.2 μm) assured sufficient core content even if the microcapsules were very small (1–10 μm). The polythiol-loaded microcapsules proved to be qualified for acting as the mate of epoxy in making two-part microencapsulated healing agent of self-healing composites.     

Preparation and characterization of microcapsules containing linseed oil and its use in self-healing coatings

Effectiveness of linseed oil filled microcapsules was investigated for healing of cracks generated in paint/coatings. Microcapsules were prepared by in situ polymerization of urea–formaldehyde resin to form shell over linseed oil droplets. Characteristics of these capsules were studied by FTIR, TGA/DSC, scanning electron microscope (SEM) and particle size analyzer. Mechanical stability was determined by stirring microcapsules in different solvents and resin solutions. Cracks in a paint film were successfully healed when linseed oil was released from microcapsules ruptured under simulated mechanical action. Linseed oil healed area was found to prevent corrosion of the substrate.