Characterization Of Microcapsules Research Articles

Microencapsulation of enzymatically destabilized virgin coconut oil by spray drying technique: Optimization of process parameters, quality assessment and studies on physico-chemical characteristics of microcapsule

Microencapsulation has gained importance in the recent decade due to its barrier properties and effective release of biochemicals. Virgin coconut oil (VCO) was obtained by enzymatic destabilization with the combination of enzymes papain (0.05 % (w/w)) and cellulase with an efficiency in oil extraction of 72.36 %. The aim of the investigation was microencapsulation of medium-chain fatty acids from coconut milk by spray drying and study the physico-chemical properties of the extracted VCO with morphological studies on the obtained microcapsules. The physicochemical properties (Iodine value = 4.24; Free Fatty Acid= 0.3 ±0.007 %; saponification value = 254 ± 4.16 (KOH/g of oil); peroxide value = 0.71 ±0.014 (meqO2/kg)) of the extracted VCO were analyzed. Medium chain fatty acids (C12: lauric acid, C10: capric acid, C8: caprylic acid) constituted 66 % of the extracted VCO, and Lauric acid (C12:0) was the most abundant medium chain fatty acid (52.7 ± 1.27 %). A five-levelled central composite rotatable design was employed with 20 runs to study the effect of inlet temperature, VCO concentration, and wall material concentration on encapsulation efficiency, oil loading %, moisture content, bulk density, water activity, and total color difference. The optimum process parameters for spray drying of VCO with best encapsulation efficiency (77.77 %), oil loading % (35.12 %), moisture content (4.69 %), bulk density (522.22 kg m-3), water activity (0.37), and total color difference (12.42) were found to be 75:25 (% w/w), proportions of GA (Gum arabic) and MD (Maltodextrin) in the wall material solution concentration, 25 (% w/w), VCO concentration and inlet air temperature of 160℃. The obtained VCO microparticle was analyzed for its powder characteristics with Carr index (2.27-11.50) and Hausner ratio (1.02-1.13), indicating good flowability. The spherical shape and smooth exterior surface of the microparticles, revealed by SEM pictures, ensured the protection and retention of VCO inside the microcapsules.

Mesoscopic study on mechanical properties and dynamic damage characteristics of self-healing microcapsule

Mesoscopic study on mechanical properties and dynamic damage characteristics of self-healing microcapsule

Fluidic microencapsulation of calcium chloride hexahydrate phase change material in resorcinol formaldehyde shell

Phase change material, encapsulated in micro-particles are required extensively in temperature control and heat storage applications. The encapsulation through random mixing and chemical emulsification does not allow use of inorganic salt as PCM that is otherwise known to be safe and effective. Microencapsulation of an inorganic phase change material in resorcinol resin shell is demonstrated here by co-flowing the two phases in a fluidic device, and inducing instability driven disintegration of core-sheath filament. Highly unimodal sized microcapsules with diameter of 978 µm ± 75 µm and uniform coating thickness were evident from the optical microscope as well as scanning electron microscope images. The heat absorption and release characteristics of microcapsules with varied shell thickness of 1.57 µm, 4.05 µm and 12.8 µm were studied by differential scanning calorimetry. The integrity of the shell was evaluated through sustained dipping of microcapsules in water, and measuring the electrical conductivity. The fractional release was restricted to about 10% of in-place PCM after 30 days. The results serve as proof of concept for the fluidic microencapsulation in general, and inorganic material in particular, which in spite of possessing many favourable aspects has not been studied till date for thermal control and energy harvesting applications.

Effects of Shellac Self-Repairing and Carbonyl Iron Powder Microcapsules on the Properties of Dulux Waterborne Coatings on Wood.

Magnetic carbonyl iron powder (CIP) microcapsules were created by in situ polymerization using melamine resin as the wall material and CIP as the core material. They were mixed with shellac self-repairing microcapsules to prepare dual-functional wood coatings, and the effect of different amounts of CIP microcapsules in the Dulux Waterborne primer on the performance of the primer was investigated. The findings demonstrated that the core-wall ratio had a significant impact on the characteristics of CIP microcapsules. The microcapsule coating rate reached 57.7% when the core-wall ratio was 0.65:1. The maximum reflection loss of CIP microcapsules with the core-wall ratio of 0.70:1 is -10.53 dB. When the addition amount of shellac self-repairing microcapsules is 4.2%, and the additional amount of CIP microcapsules with a core wall ratio of 0.65:1 and 0.70:1 is 3.0%, the coating color difference is the smallest. The number of microcapsules causes a noticeable drop in the coating's gloss, and the amount of microcapsules causes a small negative change in the coating's adherence. With an increase in the number of microcapsules, the coating's hardness, impact resistance, and tensile resistance first rose and subsequently fell. When the content of CIP microcapsules with core-wall ratio of 0.65:1 and 0.70:1 was 9.0%, the hardness, elongation at break and repair rate of the coating reached the best performance. According to a comprehensive analysis, when the content of CIP microcapsules with core-wall ratio of 0.70:1 is 9.0%, the coating has good performance. At this time, the coating has a color difference of 1.83, a glossiness of 19.3, an adhesion of 2 H, a hardness of 3 H, an impact resistance of 17 kg·cm, and a repair rate of 33.3%. This provides a technical basis for the application of multifunctional coatings on wooden substrates.

A method for real-time mechanical characterisation of microcapsules

Characterising the mechanical properties of flowing microcapsules is important from both fundamental and applied points of view. In the present study, we develop a novel multilayer perceptron (MLP)-based machine learning (ML) approach, for real-time simultaneous predictions of the membrane mechanical law type, shear and area-dilatation moduli of microcapsules, from their camera-recorded steady profiles in tube flow. By MLP, we mean a neural network where many perceptrons are organised into layers. A perceptron is a basic element that conducts input–output mapping operation. We test the performance of the present approach using both simulation and experimental data. We find that with a reasonably high prediction accuracy, our method can reach an unprecedented low prediction latency of less than 1 millisecond on a personal computer. That is the overall computational time, without using parallel computing, from a single experimental image to multiple capsule mechanical parameters. It is faster than a recently proposed convolutional neural network-based approach by two orders of magnitude, for it only deals with the one-dimensional capsule boundary instead of the entire two-dimensional capsule image. Our new approach may serve as the foundation of a promising tool for real-time mechanical characterisation and online active sorting of deformable microcapsules and biological cells in microfluidic devices.

Chitosan-Coated Alginate Microcapsules of a Full-Spectrum Cannabis Extract: Characterization, Long-Term Stability and In Vitro Bioaccessibility.

Cannabinoids present in Cannabis sativa are increasingly used in medicine due to their therapeutic potential. Moreover, the synergistic interaction between different cannabinoids and other plant constituents has led to the development of full-spectrum formulations for therapeutic treatments. In this work, the microencapsulation of a full-spectrum extract via vibration microencapsulation nozzle technique using chitosan-coated alginate is proposed to obtain an edible pharmaceutical-grade product. The suitability of microcapsules was assessed by their physicochemical characterization, long-term stability in three different storage conditions and in vitro gastrointestinal release. The synthetized microcapsules contained mainly ∆9-tetrahydrocannabinol (THC)-type and cannabinol (CBN)-type cannabinoids and had a mean size of 460 ± 260 µm and a mean sphericity of 0.5 ± 0.3. The stability assays revealed that capsules should be stored only at 4 °C in darkness to maintain their cannabinoid profile. In addition, based on the in vitro experiments, a fast intestinal release of cannabinoids ensures a medium-high bioaccessibility (57-77%) of therapeutically relevant compounds. The full characterization of microcapsules indicates that they could be used for the design of further full-spectrum cannabis oral formulations.

Numerical simulation of inhibition characteristics of wall temperature rise of phase change microcapsule in liquid-cooled microchannel

Phase change microcapsule suspension is a new type of heat-storage and heat-transfer functional fluid. Owing to the lack of understanding of flow-solid interaction, there exists a difference in research result of the heat transfer performance of suspension fluid. Therefore, the arbitrary Lagrangian-Euler method is used to simulate the flow-solid transfer characteristics of phase-change microcapsules in the liquid-cooled microchannel. Furthermore, the comparison of heat-transfer between particle and phase-change capsules is conducted. The influences of the position, shape, and number of capsules on the inhibition of the wall temperature rise are investigated. The results show that the wall-temperature-rise inhibition mainly occurs in the upstream area of the capsules. The phase change of capsules can reduce the wall temperature rise. On the other hand, the spin movement is faster when the capsule is closer to the wall, and the heat transfer is enhanced. As a result, the inhibitory effect on the wall temperature rise becomes stronger, especially near the heating surface. The circular capsules spin movement is faster and the inhibition performance is better than the ellipse. With the capsules number increasing, the wall temperature inhibition effect also gradually strengthens.

Encapsulation of hop (Humulus lupulus L.) essential oil for controlled release in the non-alcoholic beverage application

In order to increase the stability of hop ( Humulus lupulus L.) essential oil (HEO) and diversify its application into hot beverages, CAPSUL®, modified food starch, was used as the wall material to encapsulate HEO at the mass ratio of 2:1 through spray drying under 180 °C. The resultant microcapsules were applied to the non-alcoholic hop tea for the first time and their release kinetics in this matrix were analyzed by gas chromatography-mass spectrometry (GC-MS). Results showed that the reconstituted HEO emulsion possessed fine droplet size (3.295 μm) and high zeta potential (−22.50 mV). The resultant HEO microcapsules exhibited low moisture content (1.249%), suitable bulk density (0.2934 g/mL), good swelling capacity (2.235 g/g dry solids), low color difference (6.310), desirable morphological characteristics, high encapsulation efficiency (92.02–95.45%) and high flavor retention (57.13–71.15%). Each target aroma compound had its specific release behavior and mechanism from HEO microcapsules, among which β -myrcene and methyl octanoate showed the highest and lowest cumulative release respectively. This might be associated with their different volatilities, polarities, function groups and molecular sizes, or their varying hydrogen-bond formation capability at the entrance of starch helix. Most importantly, HEO microcapsules showed significant aroma increasing and stabilizing effects on the hop tea product during storage. These ideal characteristics of HEO microcapsules demonstrated the great potential of diverse essential oil microcapsules as the promising flavoring agent in a variety of hot beverage matrices. • Overall desirable physicochemical properties were observed in HEO microcapsules. • HEO microcapsule showed satisfactory encapsulation efficiency and flavor retention. • Each target aroma compound had a specific release mechanism during 40 °C of storage. • HEO microcapsule was an effective flavoring agent in the hot beverage matrix.

Effects of manufacturing conditions on the properties of boric acid/melamine-urea-formaldehyde microcapsules prepared by in situ polymerization: Its inhibition behavior on wood destroying fungi

Water-soluble boric acid (BA) was microencapsulated by in situ polymerization with a melamine-urea formaldehyde shell. The effects of core-shell ratio, time, and temperature on the microcapsule characteristics were investigated. The microencapsulated BA was tested for its effectiveness against wood-destroying fungi. The results showed that the core:shell ratio affected the individuality of the microcapsules (MCs), and the most individual microcapsules were those with the 1:1 core:shell ratio. The microencapsulation temperature at the 1:1 core:shell ratio affected the surface porosity and size spectrum of MCs. The surface was porous, and the size spectrum was narrow at 50 °C. The microencapsulation reaction time at the 1:1 core-shell ratio did not have a considerable effect on the MC size. Although the MC size spectrum varied in the studied parameters (core: shell ratio, temperature, time), the average MC sizes were large enough to pass through the bordered pits of the softwood cell wall. Slow boron release was obtained by optimizing the MC preparation parameters. The optimum microencapsulation parameters for slow release of BA were the 1:1 core:shell ratio, 50 °C, and time of 120 min. The capsules produced at optimum microencapsulation parameters were biologically active against the fungus Coniophora puteana and leaching resistance was improved.

Effects of different proteins and maltodextrin combinations as wall material on the characteristics of Cornus officinalis flavonoids microcapsules.

The flavonoids in Cornus officinalis (CO) have various pharmacological activities, however, the flavonoid instability limits its application in food and pharmaceutical industries. In this study, Cornus officinalis flavonoid (COF) microcapsules were prepared by using a combination of whey isolate protein (WPI), soy isolate protein (SPI), gelatin (GE), and maltodextrin (MD) as wall materials, respectively. Meanwhile, the encapsulation efficiency, solubility, color, particle size, thermal stability and microstructure as well as the antioxidant capacity of microcapsules were assessed. When the protein/MD ratio was 3:7, three kinds of combined wall materials realized high encapsulation efficiency (96.32–98.24%) and water solubility index (89.20–90.10%). Compared with other wall material combinations, the microcapsules with WPI-MD wall ratio at 3:7 had lower particle size (7.17 μm), lower moisture content (6.13%), higher encapsulation efficiency (98.24%), better water solubility index (90.1%), higher thermal stability (86.00°C), brightness L* (67.84) and higher 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging capacity (6.98 mgVc/g), and better flowability. Results suggested that WPI and MD could be better wall materials applied in encapsulating COF.

Progress of Microencapsulated Phycocyanin in Food and Pharma Industries: A Review.

Phycocyanin is a blue fluorescent protein with multi-bioactive functions. However, the multi-bioactivities and spectral stability of phycocyanin are susceptible to external environmental conditions, which limit its wide application. Here, the structure, properties, and biological activity of phycocyanin were discussed. This review highlights the significance of the microcapsules’ wall materials which commonly protect phycocyanin from environmental interference and summarizes the current preparation principles and characteristics of microcapsules in food and pharma industries, including spray drying, electrospinning, electrospraying, liposome delivery, sharp-hole coagulation baths, and ion gelation. Moreover, the major technical challenge and corresponding countermeasures of phycocyanin microencapsulation are also appraised, providing insights for the broader application of phycocyanin.

Studies of Encapsulation Efficiency and Swelling Behavior of Riboflavin Encapsulated by Alginate and Chitosan

Vitamin B2, also known as riboflavin, has an important function to human tissue development and energy metabolism. Riboflavin is sensitive and unstable to external influences such as light and reducing agents. In addition, most of the absorption of nutrients occurs in the intestines so the release of riboflavin in gastric need to be avoided. To overcome this problem, riboflavin was microencapsulated with sodium alginate and chitosan polymer using ionic gelation emulsification method. The purpose of this research was to study the microencapsulation itself, and also to study the effect of the riboflavin composition used upon the encapsulation efficiency and the effect of pH medium on microcapsules swelling behavior. In this research, microcapsule characterization was also carried out using FTIR and SEM. The FTIR result shows that there are crosslinking which indicated by functional groups changes between the samples during the formation of microcapsules. The SEM result show that the dried microcapsule has rougher and wrinkled surface. In efficiency encapsulation study, microencapsulation was carried out by varying the composition of riboflavin, that is 50, 75, 100, 125, and 150 mg. Optimal encapsulation efficiency was obtained at 125 mg with an efficiency encapsulation of 51.56%. The microcapsules sample were also tested for their swelling ability by putting the microcapsules into the solution with various pH ranging from 1.2, 2.5, 4.1, 5.2, 6.8 and 8. The swelling test results showed that the characteristics of microcapsules were suitable for the human digestive system because the higher the pH of the medium, then the higher the microcapsules swelling ability.

Preparation and Evaluation of Taste Masked Paracetamol Microcapsules

Paracetamol (PAR) is widely used for pediatric and geriatric patients to treat pain and fever, but it has an extremely bitter taste which poses a challenge to be formulated into suitable oral dosage forms for these age categories. This study was aimed to prepare taste-masked paracetamol microcapsules by temperature-induced phase separation technique using ethylcellulose (EC) as a wall polymer and calcium carbonate (CaCO3) as a gastro-soluble pore former. The effect of drug/polymer ratio and proportions of calcium carbonate in the wall on microcapsules characteristics were studied. The taste masking efficiency was evaluated using an in vitro dissolution model simulating oral cavity conditions. The optimized formulation was characterized by FT-IR and SEM. Results show that the particle size and the drug release in 0.1 N HCl (pH 1.2) were dependent on the drug/polymer ratio and the proportion of calcium carbonate in the wall. FT-IR spectroscopy of PAR microcapsules showed no interaction between drug and polymer. The in vitro taste masking evaluation of microparticles F8 with a drug/polymer ratio (8/1), which achieved the percent drug release more than 75% at 30min in 0.1N HCL, showed efficient taste-masking of PAR compared to the bitterness threshold.

Lutein encapsulated in whey protein and citric acid potato starch ester: Construction and characterization of microcapsules

The poor water solubility and stability of lutein limit its application in industry. Microencapsulation technology is an excellent strategy to solve these problems. This study used citric acid esterified potato starch and whey protein as an emulsifier to prepare oil-in-water lutein emulsion, and microcapsules were constructed by spray drying technology. The effects of different component proportions on microcapsules' microstructure, physical and chemical properties, and storage stability were analyzed. Citrate esterified potato starch had good emulsifying properties, and when compounded with whey protein, the encapsulation efficiency (EE) of microcapsules increased, and the embedding effect of lutein improved. After microencapsulation, the solubility of lutein increased significantly, reaching over 49.71 %, and gradually raised with more whey protein content. Furthermore, the high proportion of whey protein helped improve microcapsules' EE and thermal properties, with the maximum EE reaching 89.36 %. The glass transition temperatures of microcapsules were all higher than room temperature, which indicated that they keep a stable state under general storage conditions. The experimental results of this study may provide a reference for applying lutein in food and other fields.

THE INFLUENCE OF CORE - SHELL RATIO ON CHARACTERISTICS OF MICROCAPSULES CONTAINING CINNAMON ESSENTIAL OIL APPLIED TO AROMATHERAPEUTIC TEXTILES

Microencapsulation is one of the techniques to prepare the functional textiles. In this paper the essential cinnamon oil loaded microcapsules were prepared by solvent evaporation method. In the microencapsulation process, the core - shell ratio was changed by altering the cinnamon oil content in four levels of 0.15, 0.25, 0.35 and 0.45 g while the other components remained unchanged. The microcapsule characteristics including shape and morphology, size and size distribution, microencapsulation efficiency in dependence on the core-shell ratio were investigated. The antimicrobial capacity and the fragrance durability of interlock knitted fabric coated with the elaborated microcapsules were evaluated. The results showed that cinnamon oil was microencapsulated successfully in the spherical microcapsules. When the cinnamon oil content increased, the microcapsule size decreased and the size distribution became broader, the microcapsules were more porous and more aggregate, the fragrance intensity of the fabric treated with microcapsules increased while the activity against E. coli bacteria decreased. According to the results, the microcapsules elaborated with 0.15 g of cinnamon oil was recommended for the treatment of interlock cotton knitted fabric to apply in aroma and antimicrobial textiles.

Microencapsulation of nutmeg essential oil (Myristica fragrans) via spray drying: effects of feed emulsion parameters on emulsion and powder characteristics

Nutmeg essential oil (Myristica fragrans) is susceptible to deterioration and chemically unstable when exposed to the environment, resulting in a loss of bioactive compounds and the development of off-flavors. Microencapsulation is then used to enhance shelf stability and nutritional value. This study aimed to attempt the nutmeg essential oil encapsulation, utilizing the spray drying technique by analyzing the effect of emulsion parameters. An array of process parameters including wall material content (7, 8, and 9%), the mass ratio of carrageenan to soy protein isolate (1:2, 1:1, 2:1), and concentration of essential oil (25, 50, and 75%) were thoroughly investigated. The results showed that almost all parameters significantly influence (p < 0.05) on determining emulsion and powder quality. The microencapsulation process with a mass ratio of carrageenan to soy protein isolate of 1:2 gave better microcapsules characteristics than other powders. The microencapsulation process that was performed with a solid content of 7% as wall material and nutmeg essential oil at the concentration of 25% as core material showed the best performance, resulting in the highest solid yield (83.33±0.37%) with good emulsion characteristics (i.e. stability, viscosity, and diameter droplet) and powder properties (i.e. moisture content, total solid, hygroscopicity, and color).

Preparation and characterization of microcapsules loaded with polyphenols-enriched Uncaria tomentosa extract using spray-dryer technique

Preparation and characterization of microcapsules loaded with polyphenols-enriched Uncaria tomentosa extract using spray-dryer technique

Microencapsulation of wheat germ oil by external gelation and its oil release characteristics

In microencapsulation, composition of wall materials defines the characteristics of microcapsules, their targeted use, and bioavailability of the core material. Sodium alginate (SA) is a good candidate as a cold method to produce microcapsules, but its high cost, sodium foot prints, and digestive intolerance are the constrains. In the present study, SA was partially substituted with starch (S), pectin (P), and whey (W) to encapsulate wheat germ oil (WGO). Encapsulation efficiency was highest at 20% and 30% replacement of SA. The angle of repose was highest for S. Oil release studies were conducted in hexane, simulated gastric and intestinal fluid (SGF and SIF) without enzymes. SA with S had highest mean release in hexane (60.07%), SFG (21.11%), and SIF (72.25%) followed by P and W. The amount of oil released was lower in lower core to coating ratios and substitution of SA with polymers caused an increase in oil release. Novelty impact statement Encapsulation efficiency was highest at 20% and 30% replacement of sodium alginate. The addition of pectin increased the mean size of microcapsules of wheat germ oil. Oil released percentage in simulated gastric and intestinal fluid was less in lower core to coating ratios.

Formulation and characterization of microcapsules encapsulating carvacrol using complex coacervation crosslinked with tannic acid

Carvacrol-loaded microcapsules were developed based on coacervation complexes of whey protein isolate (WPI) and high methoxyl pectin (HMP), followed by cross-linking with tannic acid (TA). Optimal pH and WPI-HMP ratios for complex coacervation were found to be 4.1 and 5:1, respectively. Coacervation complexes were used to encapsulate carvacrol. Optimum conditions for achieving morphology and encapsulation efficiency were found for wall materials with a concentration of 2% (w/v), a wall/core ratio of 1:2 (w: w), and a homogenization speed of 15,000 rpm. The optimized formulation of microcapsules has an encapsulation efficiency of 77.48 ± 0.03% for carvacrol and a size of 1.08 μm. The addition of tannic acid (TA) decreased particle size and had no other influence on the morphological properties of microcapsules. Additionally, Fourier transform infrared spectroscopy (FTIR) indicated that coacervates were formed through the electrostatic interactions between WPI and HMP and the main force between TA and coacervates is hydrogen bonding. The addition of HMP to WPI and the presence of TA both decreased the content of tryptophan residues. Carvacrol microcapsules crosslinked with TA demonstrated better stability and antioxidant properties, showing potential for encapsulation of bioactive substances.

Morphological, rheological and thermal characteristics of biopolymeric microcapsules loaded with plant stimulants

Morphological, rheological and thermal characteristics of biopolymeric microcapsules loaded with plant stimulants