Microencapsulation: An overview on concepts, methods, properties and applications in foods

Enzymes are readily inactivated in harsh micro-environment due to changes in pH, temperature, and ionic strength. Developing suitable and feasible techniques for stabilizing enzymes in food sector is critical for preventing them from degradation. This review provides an overview on chitosan (CS)-based enzymes encapsulation techniques, enzyme release mechanisms, and their applications in food industry. The challenges and future prospects of CS-based enzymes encapsulation were also discussed. CS-based encapsulation techniques including ionotropic gelation, emulsification, spray drying, layer-by-layer self-assembly, hydrogels, and films have been studied to improve the encapsulation efficacy (EE), heat, acid and base stability of enzymes for their applications in food, agricultural, and medical industries. The smart delivery design, new delivery system development, and in vivo releasing mechanisms of enzymes using CS-based encapsulation techniques have also been evaluated in laboratory level studies. The CS-based encapsulation techniques in commercial products should be further improved for broadening their application fields. In conclusion, CS-based encapsulation techniques may provide a promising approach to improve EE and bioavailability of enzymes applied in food industry.HighlightsEnzymes play a critical role in food industries but susceptible to inactivation.Chitosan-based materials could be used to maintain the enzyme activity.Releasing mechanisms of enzymes from encapsulators were outlined.Applications of encapsulated enzymes in food fields was discussed.

In spite of the cost of silicon solar cells decreasing in recent years, there is considerable interest in solar cells with lightweight and flexible forms. Organic semiconductor-based photovoltaic cells (OPVs) have the potential to offer low cost, lightweight and flexible devices. At this stage there is still much to be improved for OPVs as the efficiencies are still lower than their inorganic counterparts. Polymeric materials have been more widely studied than their non-polymeric counterparts. In recent years OPVs polymeric donor materials have emerged with efficiencies reaching 10% with quite a range of materials now providing efficiencies of around 7%. However, the problem with semiconducting polymers is that control of the regioregularity, poly(dispersity), and molecular weight from batch-to-batch is not a simple process. Solution-processable non-polymeric semiconductors are attractive for opto-electronic applications as they are simpler to synthesise, purify, characterise, and the optical properties can be more easily fine-tuned. In this context, diketopyrrolopyrrole (DPP) based small molecules have shown promising results with devices efficiencies reaching around 5-6%. Key properties of the DPP unit are strong p-p interactions, and suitable and tunable energy levels. These properties have been the main drivers in their use in OPVs. This thesis consist of the synthesis, characterisation, and bulk hetrojunction (BHJ) devices properties of novel DPP(ThAr)2 non-polymeric materials. Accordingly, a first series of compounds was synthesized with different electron affinity groups such as fluorenone (Fl) [EhDPP(ThFl)2 and OddDPP(ThFl)2] and benzothiadiazole (Bt) [OddDPP(ThBt)2] attached to the distal ends of a bisthienyl-diketopyrrolopyrrole unit DPP(Th)2 unit. The lDPP(ThAr)2r derivatives were synthesised under standard Suzuki-Miyaura cross-coupling or by direct arylation reaction conditions and the rate of the direct arylation reaction was found to be faster than for the Suzuki-Miyaura cross-coupling reactions. The solubility of the compounds was poor when the 2-ethylhexyl (Eh) moiety was used as the solubilising group for DPP(ThFl)2. 2-Octyldodecyl (Odd) solubilising groups gave better solubility in chlorinated solvents, which are typically used in OPV fabrication. The three non-polymeric DPP materials exhibited bipolar charge transport in organic field effect transistors (OFETs), with hole and electron mobility in the order of 10-2m10-3 cm2 V-1 s-1, and in a diode architecture OddDPP(ThFl)2 and OddDPP(ThBt)2 exhibited mobilities of the order of 10-4 cm2 V-1 s-1 for pristine films. In BHJ devices using [6,6]-phenyl-C70-butyric acid methyl ester (PC70BM) as the acceptor, different solvent mixtures were used for device fabrication to achieve the maximum efficiency. The EQE spectra of the blend film suggested that charge generation due to absorption at wavelengths longer than 750 nm occurred through the Channel I pathway, and at wavelengths shorter than 750 nm, both Channel I and II pathways were in play. OddDPP(ThFl)2 was found to be the best material when acting as an electron donor in BHJ device and achieved maximum PCE of 4.1%. To further study the charge transporting properties of OddDPP(ThFl)2 based materials, its dithiane derivative (SS) [OddDPP(ThFl(SS)2)2)] was prepared. OddDPP(ThFl(SS)2)2 exhibited different thermal and optical properties, which had a direct impact on the OPV device performance and the devices performed poorly. Next, a series of OddDPP(ThBt)2 derivatives were prepared with different electron withdrawing groups, dicyanovinylene (DCV) [OddDPP(ThBt-DCV)2] and n-butyl-2-cyanoacetate (B2A) [OddDPP(ThBt-B2A)2] as end groups. The end groups had a drastic effect on both the thermal and optoelectronic properties. The materials exhibited a similar electron affinity to that of [6,6]-phenyl-C60-butyric acid methyl ester (PC60BM) and hence were used as an electron acceptor with poly(3-n-hexylthiophene) as the electron donor. OddDPP(ThBt-DCV)2 lacked sufficient solubility to be solution processed, but OddDPP(ThBt-B2A)2 could be. The EQE spectra of the OPVs suggested that the Channel II mechanism was responsible for charge generation for wavelengths above 650 nm and both Channels (I and II) wavelengths shorter than 650 nm. However, the best device efficiency was only 0.1%. A final series of materials consisted of 9,9r-bifluorenylidene (BF) and its derivatives as end groups. BF-based materials have been previously reported to give rise to electron accepting materials. In this series the basic structure was kept same, with the difference being simple addition of methoxy groups (OMe) or fluorine (F) atoms to OddDPP(ThBF)2 to form OddDPP(ThBF(OMe)2)2) and (OddDPP(ThBF(F)2)2), respectively. However, only the parent OddDPP(ThBF)2 and the methoxy derivative, OddDPP(ThBF(OMe)2)2 could be purified and characterised. The materials exhibited different thermal phase transition behaviours, but had similar optoelectronic properties. Devices fabricated with BF derivatives and the acceptor (PC70BM) from chloroform and chloroform with 10% dichlorobenzene exhibited similar device performance. However, the device performance was poor. Interestingly, the film fabricated from chloroform with 0.5% 1,8-diiodooctane (DIO) exhibited the best device performance and the OddDPP(ThBF)2:PC70BM OPV had an efficiency of 2.6%.

A comprehensive review of starch-based technology for encapsulation of flavor: From methods, materials, and release mechanism to applications

This study examines the hygroscopic and surface tension properties as a function of photochemical aging of the aerosol emissions from biomass burning. Experiments were conducted in a chamber setting at the UC-Riverside Center for Environmental Research and Technology (CE-CERT) Atmospheric Processes Lab using two biomass fuel sources, manzanita and chamise. Cloud condensation nuclei (CCN) measurements and off-line filter sample analysis were conducted. The water-soluble organic carbon content and surface tension of the extracted filter samples were measured. Surface tension information was then examined with Köhler theory analysis to calculate the hygroscopicity parameter, κ. Laboratory measurement of biomass burning smoke from two chaparral fuels is shown to depress the surface tension of water by 30% or more at organic matter concentrations relevant at droplet activation. Accounting for surface tension depression can lower the calculated κ by a factor of 2. This work provides evidence for surface tension depression in an important aerosol system and may provide closure for differing sub- and supersaturated κ measurements.

In recent decades, the microcapsules of lipids, compound lipids, and essential oils, have found numerous potential practical applications in food, textiles, agricultural products, as well as pharmaceuticals. This article discusses the encapsulation of fat-soluble vitamins, essential oils, polyunsaturated fatty acids, and structured lipids. Consequently, the compiled information establishes the criteria to better select encapsulating agents as well as combinations of encapsulating agents best suited to the types of active ingredient to be encapsulated. This review shows a trend towards applications in food and pharmacology as well as the increase in research related to microencapsulation by the spray drying of vitamins A and E, as well as fish oil, thanks to its contribution of omega 3 and omega 6. There is also an increase in articles in which spray drying is combined with other encapsulation techniques, or modifications to the conventional spray drying system.

Lipophilic bioactive materials, such as carotenoids, exhibit various health benefits. To enhance their stability and application in food and pharmaceutical industries, feasibility of microencapsulating these bioactive materials by spray drying was investigated. High‐ and low‐energy emulsification methods were compared at various emulsion compositions and their effects on emulsion stability were characterized. High‐energy method was preferred for safety concerns, as it was able to produce fine emulsions (davg < 400 nm) at relatively low surfactant‐to‐oil ratio. The formed infeed emulsions, with MCT oil as core material, gelatin as wall material and primary emulsifier and Tween 80 as secondary emulsifier, were then spray dried using a lab scale spray dryer (Büchi B‐290). Operating conditions were optimized and results demonstrated that spray drying technology could be applied to transform stable infeed emulsions (containing bioactive materials) into microcapsules with desired properties (e.g., low moisture content (5.5–7% (d.b.)), relatively narrow size distribution (d50 between 9.8 and 10.8 μm), and high encapsulation efficiency (around 90%)). So, it is feasible to use this emulsion‐based system to microencapsulate bioactive materials by spray drying.Practical applicationLipophilic bioactive elements are highly susceptible to adverse environment conditions. To overcome these problems, feasibility of microencapsulating these bioactive materials by spray drying was investigated in the present study. A high‐energy method was compared with a low‐energy method in order to find an appropriate emulsification method. The formed infeed emulsion was then spray dried to determine optimum operating conditions. This research should be useful for identifying the most appropriate operating conditions for lipophilic bioactive materials microencapsulation for industrial application especially in food and pharmaceutical industries. Meanwhile, it also provides a possible reference for other scientists and researchers.

Natural polymer is a frequently used polymer in various food applications and pharmaceutical formulations due to its benefits and its biocompatibility compared to synthetic polymers. One of the natural polymer groups (i.e., polysaccharide) does not only function as an additive in pharmaceutical preparations, but also as an active ingredient with pharmacological effects. In addition, several natural polymers offer potential distinct applications in gene delivery and genetic engineering. However, some of these polymers have drawbacks, such as their lack of water retention and elasticity. Sacran, one of the high-molecular-weight natural polysaccharides (megamolecular polysaccharides) derived from Aphanothece sacrum (A. sacrum), has good water retention and elasticity. Historically, sacran has been used as a dietary food. Moreover, sacran can be applied in biomedical fields as an active material, excipient, and genetic engineering material. This article discusses the characteristics, extraction, isolation procedures, and the use of sacran in food and biomedical applications.

The article focuses on the physical properties of nanofluids based on ethylene glycol (EG) with dispersed zirconium dioxide (ZrO2) nanoparticles. For this purpose, the two-step method was applied to prepare samples with five different nanoadditive volume fractions (0.002, 0.004, 0.006, 0.0081, 0.0102). No surfactants were used in the sample preparation process. All materials are commercially available and were used without any modification. To determine the physical properties of ZrO2-EG nanofluids, various techniques were used. Oscillating U-tube method, Du Noüy ring method Ohm law, and dielectric spectroscopy were applied to obtain the mass density, surface tension, electrical conductivity and permittivity, respectively. All measurements were performed at a constant temperature of 298.15 K. The effect of nanoparticles volume fraction on the physical properties of the prepared nanofluids was determined. The mass density, surface tension, electrical conductivity and permittivity increase with the increasing content of ZrO2 in ethylene glycol.

Two intermolecular potential models of methanol (TraPPE-UA and OPLS-AA) have been used in order to examine their validity in reproducing the selected structural, dynamical, and thermodynamic properties in the unary and binary systems. These two models are combined with two water models (SPC/E and TIP4P). The temperature dependence of density, surface tension, diffusion and structural properties for the unary system has been computed over specific range of temperatures (200-300K). The very good performance of the TraPPE-UA potential model in predicting surface tension, diffusion, structure, and density of the unary system led us to examine its accuracy and performance in its aqueous solution. In the binary system the same properties were examined, using different mole fractions of methanol. The TraPPE-UA model combined with TIP4P-water shows a very good agreement with the experimental results for density and surface tension properties; whereas the OPLS-AA combined with SPCE-water shows a very agreement with experimental results regarding the diffusion coefficients. Two different approaches have been used in calculating the diffusion coefficient in the mixture, namely the Einstein equation (EE) and Green-Kubo (GK) method. Our results show the advantageous of applying GK over EE in reproducing the experimental results and in saving computer time.

The goal of the present work is to find a suitable method for developing β-carotene aerosols by varying core (active material) to wall (excipient) ratios (1:10, 1:25, and 1:50). For this, spray freeze drying (SFD) and spray drying (SD) techniques were adopted to develop aerosols. The results revealed that aerosols from SFD had low density and free-flowing behavior; whereas, SD samples were cohesive. SFD aerosols were porous and SD samples had smooth structures, with sizes of 8.3 to 9.3 and 9.3 to 9.6 µm, respectively. All formulations exhibited good mass median aerodynamic diameter (MMADt) of 3.75 to 6.96 µm and % emitted dosage was found higher in SFD aerosols (around 57 to 60%). Release of β-carotene through the in-vitro study was found higher in SFD samples and controlled release was observed in 1:50 formulation. In 12 h release, around 64% and 74% contents were released from SD and SFD aerosol samples, respectively. Particle density, size, and morphology strongly affect particle deposition in the lungs’ and this approach can be conveniently scale-up for pulmonary supplementation of food bioactive compounds.

Pomegranate peel waste is a valuable reservoir of heat-sensitive total hydrolysable tannins (THT), with potential applications in food and pharmaceuticals. Preserving THT is challenging due to degradation post-extraction. We explore ionic gelation as an encapsulation method to optimize THT utilization. Through external gelation, we optimized the process variables using Box-Behnken design. At 40 g kg-1 sodium alginate, 25 g kg-1 calcium chloride, and 300 g kg-1 pomegranate peel extract (PPE), we achieved an 83.65% encapsulation efficiency. Compared to spray drying, external gelation demonstrated superior performance, with enhanced release percentages and stability. Physical, phytochemical, and release profiles of encapsulates were extensively analysed. External gelation achieved an 87.5% release in 30 min, outperforming spray-dried counterparts (69.7% in 25 min). Encapsulated PPE exhibited robust antibacterial activity against Staphylococcus aureus (ATCC 25923) in powdered infant formula, with a 32 ± 0.01 mm zone of inhibition and 300 μg mL-1 minimum inhibitory concentration. Insights into S. aureus growth curves underlined the mechanism of action via membrane potential alterations. The results of carried investigations also showed that the antibacterial activity of the encapsulated PPE extracts against the targeted organism was identical to the antibacterial activity exhibited by synthetic antibiotics used generally to kill microorganisms in food. Therefore, from the findings, it can be concluded that the PPE encapsulate produced using the external gelation technique at the optimized condition displayed superior storage stability possessing strong antimicrobial activity when compared to encapsulate produced using the spray drying technique. External gelation emerges as a potent technique for developing effective encapsulates enriched with natural antimicrobials or antibiotics. This approach holds promise for applications in food, pharmaceuticals, and nutraceuticals, enhancing stability and efficacy while reducing reliance on synthetic antibiotics. © 2024 Society of Chemical Industry.

Aim Evaluate the stability of microparticles loaded with fish oil produced by spray drying, spray chilling and by the combination of these techniques (double-shell) and use the microparticles for food application. Methods Samples were stored for 180 days at 6 °C and 24 °C (75% RH). Performed investigations included encapsulation efficiency, moisture content, aw, size (laser scattering), colour (L*, a*, b*), polyunsaturated fatty acids (PUFAs) (GC), thermal behaviour (DSC) and crystalline structure (XRD). Results Double-shell microparticles containing 26 wt% core material, 22.74 ± 0.02 µm (D0.5) and 2.05 ± 0.03 span index, 1.262 ± 0.026 wt% moisture content and 0.240 ± 0.001 of aw had PUFAs retention higher than 90 wt% during storage at 6 °C without changes in crystalline structure (β’-type crystals) and melting temperature (54 °C). The sensory evaluation suggested low fish oil release in oral phase digestion. Conclusions Double-shell microparticles were effective to protect and deliver PUFAs.

Spray drying is one of the most preferred preservation methods that converts an aqueous feed containing solvent, carrier agent, and food compounds into dry powder with superb physicochemical and functional properties. This paper reviews the fundamental and important operating parameters, product characteristics, current and potential applications, and techno-economic aspects of spray drying. The key operating parameters should be chosen to achieve the highest spray drying performance in terms of operational efficiency and product quality. A successful spray drying operation is greatly dependent on the feed material properties, the mechanical design of the equipment, and selected operating parameters. This paper also found that water content, water activity, and glass transition temperature are the main parameters that really determine product quality in terms of shelf life and storage conditions of food powder obtained from the spray drying process. Recent advances in the development of new heatless spray drying technology in the manufacture of food flavoring and nutraceuticals are interesting to develop, in addition to the potential to produce nano-sized powders with distinctive properties and the use of superheated steam and carbon dioxide to sterilize products. The appropriate information on spray drying technology featured in this paper is targeted to reinforce researcher and practitioner understanding for widening its applications in pertinent food industries. Doi: 10.28991/HEF-2024-05-02-09 Full Text: PDF

Dragon fruit is a popular fruit grown in Malaysia. It is well known for the rich nutrient contents, and it is commercially available worldwide. It is rich in anthocyanins and antioxidants. Dragon fruit is also an essential source of betacyanin, which serves as a red/purple pigment with antioxidative properties. The objective of the present work is to study the stability of natural colorant from dragon fruit peel. The crushed peel and water were taken in the ratio of 1:10 and was subjected to seven different types of extraction techniques such as microwave-assisted extraction, ohmic heating, ultrahigh-pressure homogenization, sonicator, supercritical fluid extraction, aqueous extraction, Soxhlet extraction. Out of the microwave-assisted extraction had the most Anthocyanin content, and it was used for further studies. The selected extract was filtered, and the stability of anthocyanin was examined at varying pH (2…10) and temperature (60…100⁰C). In addition to this, thermal stability (80…100 ⁰C for 150 min) was checked at a deferent time interval (80 to 100⁰C…150 min.). The microwave extract was used for the encapsulation process using maltodextrin, and soy protein isolate as carrier material with 1:4, 1:5 core to wall ratio by spray drying and freeze-drying techniques. The quality analysis, such as total anthocyanin content, encapsulation efficiency, color, water activity, bulk density, solubility, and moisture content, were analyzed of microencapsulated anthocyanin extract. This result showed that encapsulated dragon fruit peel (pitaya) powder could be used as a natural colorant in food applications.

The purpose for the current research is to compare and evaluate physiochemical properties of spray-dried (SD) microcrystals (MCs), nanocrystals (NCs), and nanocrystals with a dispersion agent (NCm) from a poorly soluble compound. The characterization was carried out by performing size and surface analysis, interfacial tension (at particle moisture interface), and in-vitro drug dissolution rate experiments. Nanosuspensions were prepared by media milling and were spray-dried. The SD powders that were obtained were characterized morphologically using scanning electron microscopy (SEM), polarized light microscopy (PLM), and Flowchem. Solid-state characterization was performed using X-ray powder diffraction (XRPD), Fourier transfer infrared spectroscopy (FT-IR), and differential scanning calorimetry (DSC) for the identification of the crystalline nature of all the SD powders. The powders were characterized for their redispersion tendency in the water and in pH 1.2. Significant differences in redispersion were noted for both the NCs in both dissolution media. The interfacial tension for particle moisture interface was determined by applying the BET (Braunauer–Emmett–Teller) equation to the vapor sorption data. No significant reduction in the interfacial tension was observed between MCs and NCs; however, a significant reduction in the interfacial tension was observed for NCm at both 25 °C and 35 °C temperatures. The difference in interfacial tension and redispersion behavior can be attributed to a difference in the wetting tendency for all the SD powders. The dissolution studies were carried out under sink and under non-sink conditions. The non-sink dissolution approach was found suitable for quantification of the dissolution rate enhancement, and also for providing the rank order to the SD formulations.