喷雾干燥法制备微胶囊工艺研究

主要介绍了喷雾干燥技术制备微胶囊过程中的乳化液配置及相关喷雾干燥工艺参数对微胶囊化过程的影响.     

Spray-Drying Microencapsulation of Anthocyanins by Natural Biopolymers: A Review

There has been an increased interest in the development of food colorants from natural sources as alternatives to synthetic dyes because of both legislative actions and consumer concerns. Anthocyanins are of great interest for the food industry since they give a wide range of colors as well as nutraceutical activities. Nevertheless, due to their low stability to environmental conditions during processing and storage, introducing those compounds into foods is challenging. Microencapsulation may be an efficient way to introduce such compounds into those products. An important step in developing microcapsules is the selection of a biopolymer (wall material) which meets the required criteria. Hence, this review will focus on microencapsulation of anthocyanins with different biopolymers through spray drying to develop natural colorant pigments which possess high stability, solubility, and dispersibility. Our goal is to give updated information regarding microencapsulation of anthocyanins by spray drying, as well as its effectiveness, developments, and optimized conditions which will be discussed.     

Effect of Selected Additives on Microencapsulation of Anthocyanin by Spray Drying

Microencapsulation of anthocyanin pigment present in Garcinia indica Choisy was carried out with maltodextrin of various dextrose equivalents (DE 06, 19, 21, and 33) and other additives such as gum acacia and tricalcium phosphate to enhance the stability of the pigment. The microencapsulated pigment containing 5.0% maltodextrin DE 21, 0.25% gum acacia, and 0.25% tricalcium phosphate was found to have lowest hygroscopic moisture content (4.38%), highest antioxidant activity (69.90%), and highest anthocyanin content (485 mg/100 g). The glass transition temperature was 44.59°C. The sorption isotherms for microencapsulated powder showed that the samples were stable up to water activity less than 0.43. The scanning electron microscope structures depicted that the particle size ranged from 5 to 50 μm with smooth spheres. Storage at 4°C increased the half-life twofold compared to that of the spray-dried product kept at ambient temperature (25°C).     

Manufacturing Drug Loaded Chitosan Microspheres by Spray Drying: Development, Characterization, and Potential Use in Dentistry

The aim of this work was to determine specifications for spray-drying manufacturing of sustained-release drug-loaded microparticles with potential application in dentistry. Chitosan was used as the microencapsulation polymer and ketoprofen as the model drug. A 1:1 chitosan/ketoprofen suspension was spray-dried under different operating conditions. The size distribution, morphology, total drug load, and release profile of the powders were characterized. In vitro release studies were performed with the powder samples entrapped in cellulose dialysis tubes. The microparticles produced had a narrow size distribution (mean diameter ranging from 2.11 to 3.27 µm), good sphericity, and a smooth surface. In vitro release studies showed a linear drug dissolution behavior.     

Manufacturing Drug Loaded Chitosan Microspheres by Spray Drying: Development,Characterization, and Potential Use in Dentistry

The aim of this work was to determine specifications for spray-drying manufacturing of sustained-release drug-loaded microparticles with potential application in dentistry. Chitosan was used as the microencapsulation polymer and ketoprofen as the model drug. A 1:1 chitosan/ketoprofen suspension was spray-dried under different operating conditions. The size distribution, morphology, total drug load, and release profile of the powders were characterized. In vitro release studies were performed with the powder samples entrapped in cellulose dialysis tubes. The microparticles produced had a narrow size distribution (mean diameter ranging from 2.11 to 3.27 µm), good sphericity, and a smooth surface. In vitro release studies showed a linear drug dissolution behavior.     

The effect of formulation variables on the dissolution and physical properties of spray-dried microspheres containing organic salts

In the present work, the spray drying technique was used in formulating calcium microparticles from aqueous systems: dispersions of calcium citrate and solutions of calcium lactate were incorporated with polymers and dispersed into a hot air stream as small droplets, leading to the formation of solid microparticles. Different kinds of polymers (cellulose derivatives and polymethacrylic acid) were studied to evaluate their spray-coating properties and the release profiles. In addition, some physical properties of the microparticles were also determined. The results showed that the calcium release from the microparticles containing both organic calcium salts into a simulated gastrointestinal medium, as well as the microparticles size and morphology can be modified by varying the proportion and the type of the polymer used as encapsulating agent.     

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.     

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.     

Microencapsulation in foam spray drying

Abstract

The article presents the results of the experiments of gas-admixing foam spray drying microencapsulation of oil in co-current spray drying tower. The introduction of a foaming gas resulted in a decrease of encapsulation efficiency: for high foaming gas/liquid ratio (GLR) 6.43·10^?3 kg/kg and T_air,0=215?°C by over 50% relative to the non-foaming process due to damage of the microcapsule structure and leakage of the oil phase to the particle surface. For moderate drying temperatures and GLR, 80% of microencapsulation efficiency might be achieved with simultaneous control of selected product properties like apparent and bulk density or angle of repose. Abbreviations GLR gas-to-liquid ratio

HR Hausner ratio

MDX maltodextrin

PSD particle size distribution

SEM scanning electron microscope.

     

Sodium Humate as a Promising Coating Material for Microencapsulation of Beauveria bassiana Conidia Through Spray Drying

Microencapsulation of Beauveria bassiana (Bb) conidia with sodium humate (SH) was undertaken successfully through spray drying at a high inlet air temperature of 175°C with corresponding outlet air temperature of 86.5 ± 1.3°C using 0.2% SH. The obtained product was a free-flowing, dark-brown powder containing microcapsules of Bb conidia coated with sodium humate (Bb-SH). These microcapsules measured 2.47–3.57 µm and possessed an uneven, fluffy surface. The colony-forming units (CFU) of Bb-SH microcapsules spray-dried at 175°C were 21.54 LCFUg^?1, on par with 21.59 LCFUg^?1 for Bb conidial powder not subjected to spray drying. Bb-SH microcapsules resulted in a high mortality of 93.0% against six-day-old Helicoverpa armigera larvae within five days after treatment. Bb-SH microcapsules readily dispersed in water, releasing sodium humate from the conidial surface. Germination of conidia was not affected by sodium humate as visualized by scanning electron microscopy of the cuticular surface of treated larvae. Bb-SH microcapsules showed good viability (21.11 LCFUg^?1) at the end of six months of storage at room temperature (～30°). Thus, sodium humate is a promising biopolymer for encapsulation of Bb conidia for extended shelf-life at room temperature.     

Microencapsulation of Flaxseed Oil by Spray Drying: Effect of Oil Load and Type of Wall Material

The objective of this work was to evaluate the effect of the type of wall material and the oil load on the microencapsulation of flaxseed oil by spray drying. Gum arabic, whey protein concentrate, and a modified starch were used to produce the microcapsules, each with four oil concentrations (10, 20, 30, and 40% oil, w/w, with respect to total solids), for a total of 12 tests. Initially, the feed emulsions were characterized for stability, viscosity, and droplet size. Then they were dried in a laboratory-scale spray dryer and the resulting particles were analyzed for encapsulation efficiency, lipid oxidation, moisture content, and bulk density. The increase in oil concentration led to the production of emulsions with larger droplets and lower viscosity, which directly affected powder properties, resulting in lower encapsulation efficiency and higher lipid oxidation. Among the three wall materials evaluated, the modified starch showed the best performance, with the highest encapsulation efficiency and lowest peroxide values.     

Microencapsulation of Ketoprofen in Blends of Acrylic Resins by Spray Drying

Microparticles of ketoprofen entrapped in blends of acrylic resins (Eudragit RL 30D and RS 30D) were successfully produced by spray drying. The effects of the proportion ketoprofen : polymer (1:1 and 1:3) and of spray-drying parameters (drying gas inlet temperatures of 80 and 100°C; microencapsulating composition feed flow rates of 4 and 6 g/min) on the microparticles properties (drug content, encapsulation efficiency, mean particle size, moisture content, and dissolution behavior) were evaluated. Differential scanning calorimetry (DSC) thermograms and X-ray diffractograms of the spray-dried product, the free drug, and the physical mixture between the free drug and spray-dried composition (blank) were carried out. Microparticles obtained at inlet temperature of 80°C, feed flow rate of 4 g/min, and ketoprofen : acrylic resin ratio of 1:3 presented an encapsulation efficiency of 88.1%, moisture content of 5.8%, production yield around 50%, and a higher reduction in dissolution rate of the entrapped ketoprofen. Sigmoidal shape dissolution profiles were presented by the spray-dried microparticles. The dissolution profiles were relatively well described by the Weibull model, a showing high coefficient of determination, R ², and a mean absolute error between experimental and estimated values of between 4.6 and 10.1%.     

Microencapsulation of Gac Oil by Spray Drying: Optimization of Wall Material Concentration and Oil Load Using Response Surface Methodology

The objective of this study was to optimize the wall material concentration and the oil load on the encapsulation of Gac oil using spray drying by response surface methodology. Results showed that the quadratic polynomial model was sufficient to describe and predict encapsulation efficiencies in terms of oil, β-carotene, lycopene, peroxide value (PV), moisture content (MC), and total color difference (Δ E) with R ² values of 0.96, 0.95, 0.86, 0.89, 0.88, and 0.87, respectively. Under optimum conditions (wall concentration of 29.5 % and oil load of 0.2), the encapsulation efficiencies for oil, β-carotene, lycopene, PV, MC, and Δ E were predicted and confirmed as 92 %, 80 %, 74 %, 3.91 meq/kg, 4.14 % and 12.38, respectively. The physical properties of the encapsulated oil powders obtained by different formulations were also determined. It was concluded that the protein-polysaccharide matrix as the wall material was effectively used for spray-drying encapsulation of Gac oil.     

Effect of homogenization parameters on selected physical properties of lemon aroma powder

The aim of this study was to examine the relationship between homogenization parameters of lemon aroma emulsion and selected physical properties of obtained powders. Emulsion was prepared in a high shear homogenizer (10 min, 24,000 rpm) or a two-stage pressure homogenizer (30_10 or 60_20 MPa). A 30% emulsion of maltodextrin and Arabic gum in the ratio 7:1 by mass in water and aroma was prepared. The addition of lemon aroma was 2, 6 and 10% (w/w). It was found that in emulsions an increase of aroma addition caused an increase in diameter from 2.4 to 4 μm for Ultra Turrax high shear homogenization and did not change the diameter size for pressure homogenization. For pressure homogenization similar viscosity values were observed. A different effect was observed for high shear homogenization (31–40 mPa s). Increase in aroma addition caused an increase in viscosity. Moreover, a similar diameter of the aroma phase after reconstitution of emulsion from powder (0.7–1.3 μm) was observed. In powders with an increasing amount of aroma, regardless of homogenization method, an increase in porosity, spread of particle size and total colour differences and also a decrease in loose bulk density, solubility and lightness were observed. The lowest apparent density of powders was found for an emulsion containing 6% aroma. The shape of powder particles did not differ from themselves.     

MODELING MASS TRANSFER OF FITC-LABELED DEXTRAN FROM POLYELECTROLYTE MICROCAPSULES

Layer-by-layer adsorption of oppositely charged polyelectrolytes has been used for the manufacturing of hollow microspheres or capsules for controlled release studies. Using this self-assembly technique, microsphere core material was encapsulated with poly styrenesulfonate (PSS) and poly allylamine (PAH) multilayers or PAH and polyvinyl sulfate (PVS) multilayers and the core dissolved to produce hollow microcapsules. The microspheres were loaded with fluorescein-isothiocyanate (FITC)-labeled dextran of different molecular weights for different lengths of time to quantify the release properties. After loading, the capsules were immersed in water and the FITC-dextran was allowed to diffuse into the mother liquor. The FITC-dextran concentration of the mother liquor was measured over a period of hours and days. In this study, one- and two-compartment models were developed, based on a species mass balance, to predict the concentration of dextran release from the microcapsules over time. The two-compartment model was found to be superior to the one-compartment model in its fit to the observed data. The model was applied to experimental data in order to characterize the release properties of microcapsules with different numbers of layers and constituent architectures.     

Drug Release Kinetics of Spray-Dried Chitosan Microspheres

The aim of this article was to investigate the drug release kinetics of spray-dried chitosan microspheres using various kinetic models. The mean particle size and encapsulation efficiency of cross-linked chitosan microspheres was between 3.8 and 4.2 μm and 96.3 and 98.7%, respectively. Spray-dried chitosan microspheres were spherical in shape with smooth surface. The surface morphology of spray-dried chitosan microspheres was affected by the crystallinity of the loaded drug and cross-linking agent. The release data of the spray-dried chitosan microspheres were treated with zero-order, first-order, Higuchi, Korsmeyer, and Kopcha kinetic models and best fit was observed with Higuchi model, indicating the release of drug from spray-dried chitosan microspheres followed Fick's law of diffusion.     

Drug Release Kinetics of Spray-Dried Chitosan Microspheres

The aim of this article was to investigate the drug release kinetics of spray-dried chitosan microspheres using various kinetic models. The mean particle size and encapsulation efficiency of cross-linked chitosan microspheres was between 3.8 and 4.2 μm and 96.3 and 98.7%, respectively. Spray-dried chitosan microspheres were spherical in shape with smooth surface. The surface morphology of spray-dried chitosan microspheres was affected by the crystallinity of the loaded drug and cross-linking agent. The release data of the spray-dried chitosan microspheres were treated with zero-order, first-order, Higuchi, Korsmeyer, and Kopcha kinetic models and best fit was observed with Higuchi model, indicating the release of drug from spray-dried chitosan microspheres followed Fick's law of diffusion.     

Stabilization of Lipoxygenase-1 from Glycine max by Microencapsulation

Lipoxygenase from soybean was encapsulated and the effect of different carrier materials (whey protein, gum arabic, whey protein along with sodium alginate and maltodextrin) on enzyme stability during spray drying was studied and compared with freeze drying. The addition of polyethylene glycol (PEG-4000) during spray drying evidently enhanced enzyme stability. Total activity of lipoxygenase after spray drying was 1.14 × 10⁴(whey protein isolate), 1.2 × 10⁴(gum arabic), 1.09 × 10⁴ (whey protein isolate + sodium alginate), 1.44 × 10⁴(maltodextrin), and 1.55 × 10⁴(PEG + maltodextrin). Highest enzyme activity recovery of 72.02% was achieved with the combined addition of maltodextrin and PEG-4000. Moisture, scanning electron microscopy analysis, and storage studies were carried out for spray- and freeze-dried enzyme.     

Microencapsulation of extra‐virgin olive oil by spray‐drying: Influence of wall material and olive quality

Encapsulation is a process by which small particles of core products are packaged within a wall material to form microcapsules. One common technique to produce encapsulated products is spray‐drying which involves the conversion of liquid oils in the form of an emulsion into dry powders. Emulsification conditions, wall components, and spray‐drying parameters have been optimized for the microencapsulation of different extra‐virgin olive oils. To achieve this goal, the influences of emulsion conditions have been evaluated for different wall components such as proteins (sodium caseinate and gelatin), hydrocolloids (Arabic gum), and hydrolyzed starches (starch, lactose, and maltodextrin). In addition, for each of the tested conditions the ratio of wall solid‐to‐oil and spray‐drying parameters were as well optimized. The microencapsulation effectiveness was determined based on process yield and the ratio between free and encapsulated oil (microencapsulation efficiency). Highest encapsulation yields were achieved when gelatin, Arabic gum and maltodextrin and sodium caseinate and maltodextrin were used as encapsulation agents and the ratio of wall solid‐to‐oil was 1:4 and 1:2, respectively. Under these conditions, 53% of oil was encapsulated. The influence of olive oil quality in the microencapsulation process was evaluated in terms of fatty acids profile alteration after the microencapsulation process.