Complex Coacervation Process Research Articles

Encapsulation of Essential Oils Using Complex Coacervation: A Study on Microcapsule Formation and Efficiency

Encapsulation by Coacervation is a process used to create microcapsules. Coacervation is a process that has been used in the food and pharmaceutical industry to produce microspheres with an active ingredient, such as drugs, flavors or fragrances encapsulated by them. It is common in pharmacies, food preparation, cosmetics, and agriculture. This phase separation process is called Coacervation, where a colloidal (in this case polymer) solution will separate into two distinct liquid phases: a Polymer-rich phase, which we refer to as the coacervate, and the other is known as Polymer-poor or solvent-based. This can be accomplished by varying the temperature or pH of a non-solvent being introduced. In this study, essential oils of lemon and eucalyptus were encapsulated by the complex coacervation process using gum Arabic, gelatin, and chitosan as wall materials. Glutaraldehyde was used as a cross-linking agent in the methodology. FT-IR and GC characterized the essential oils used. The microcapsules were analyzed using a digital microscope, scanning electron microscopy (SEM), and thermogravimetric analysis. Conclusively, microcapsules were formed in spherical form. Encapsulation efficiencies were obtained between 75-78%. In conclusion, microencapsulated essential oils offer a technology that makes essential oils more effective, long-lasting, and customized. These advantages reveal their widespread impact, offering various uses for a variety of industries and applications.

Coacervation in Slow Motion: Kinetics of Complex Micelle Formation Induced by the Hydrolysis of an Antibiotic Prodrug.

Colistin methanesulfonate (CMS) is the less-toxic prodrug of highly nephrotoxic colistin. To develop and understand highly necessary new antibiotic formulations, the hydrolysis of CMS to colistin must be better understood. Herein, with the addition of poly(ethylene oxide)-b-poly(methacrylic acid) (PEO-b-PMAA) to CMS, we show that we can follow the hydrolysis kinetics, employing small-angle X-ray scattering (SAXS) through complex coacervation. During this hydrolysis, hydroxy methanesulfonate (HMS) groups from CMS are cleaved, while the newly formed cationic amino groups complex with the anionic charge from the PMAA block. As the hydrolysis of HMS groups is slow, we can follow the complex coacervation process by the gradual formation of complex micelles containing activated antibiotics. Combining mass spectrometry (MS) with SAXS, we quantify the hydrolysis as a function of pH. Upon modeling the kinetic pathways, we found that complexation only happens after complete hydrolysis into colistin and that the process is accelerated under acidic conditions. At pH = 5.0, effective charge switching was identified as the slowest step in the CMS conversion, constituting the rate-limiting step in colistin formation.

Understanding emulsifier influence on complex coacervation: Essential oils encapsulation perspective.

The objective of this research was to explore the viability of pea protein as a substitute for gelatin in the complex coacervation process, with a specific focus on understanding the impact of incorporating an emulsifier into this process. The study involved the preparation of samples with varying polymer mixing ratios (1:1, 1:2, and 2:1) and emulsifier content. As core substances, black pepper and juniper essential oils were utilized, dissolved beforehand in grape seed oil or soybean oil, to minimize the loss of volatile compounds. In total, 24 distinct samples were created, subjected to freeze-drying to produce powder, and then assessed for their physicochemical properties. Results revealed the significant impact of emulsifier addition on microcapsule parameters. Powders lacking emulsifiers exhibited higher water solubility (57.10%-81.41%) compared to those with emulsifiers (24.64%-40.13%). Moreover, the emulsifier significantly decreased thermal stability (e.g., without emulsifier, Ton=137.21°C; with emulsifier, Ton=41.55°C) and adversely impacted encapsulation efficiency (highest efficiency achieved: 67%; with emulsifier: 21%).

Encapsulation of Bacillus thuringiensis using sodium alginate and chitosan coacervates for insect-pest management

The study investigates the complex coacervation process of sodium alginate (SA) and chitosan (CS), aiming to optimize the yield of coacervates formed from these marine polysaccharides. Structural interactions between SA and CS were analyzed across varying chitosan concentrations (0.01 mg to 20 mg/mL) using turbidimetric analysis. The optimal chitosan concentration for maximum coacervate formation was determined to be 10 mg/mL. Under these conditions, Bacillus thuringiensis var. kurstaki (Bt) strain Bt-127 was successfully microencapsulated, achieving an entrapment rate of 56 %. Boric acid was selected as the cross-linking agent due to its compatibility with Bt and the SA-CS coacervates. Microscopic analysis confirmed the formation of coacervates/microcapsules and effective entrapment of Bt within them, with an entrapment efficiency of 98 %. Fourier transform infrared spectroscopy verified the chemical interactions between SA and CS within the coacervates. Bioassays against Spodoptera litura larvae using the leaf dip method demonstrated the efficacy of the encapsulated Bt formulation, showing an LC50 of 0.51 g/L. These findings highlight the potential of SA-CS coacervates for effective Bt microencapsulation and application in pest control.

Microencapsulation of Essential Oils Using Faba Bean Protein and Chia Seed Polysaccharides via Complex Coacervation Method.

The aim of this study was to develop microcapsules containing juniper or black pepper essential oils, using a combination of faba bean protein and chia seed polysaccharides (in ratios of 1:1, 1:2, 2:1). By synergizing these two polymers, our goal was to enhance the efficiency of essential oil microencapsulation, opening up various applications in the food industry. Additionally, we aimed to investigate the influence of different polymer mixing ratios on the properties of the resulting microcapsules and the course of the complex coacervation process. To dissolve the essential oils and limit their evaporation, soybean and rapeseed oils were used. The powders resulting from the freeze-drying of coacervates underwent testing to assess microencapsulation efficiency (65.64-87.85%), density, flowability, water content, solubility, and hygroscopicity. Additionally, FT-IR and DSC analyses were conducted. FT-IR analysis confirmed the interactions between the components of the microcapsules, and these interactions were reflected in their high thermal resistance, especially at a protein-to-polysaccharide ratio of 2:1 (177.2 °C). The water content in the obtained powders was low (3.72-7.65%), but it contributed to their hygroscopicity (40.40-76.98%).

Highly Stable Microcapsules of Colloidal Photonic Ink in Nonpolar Medium for Full Color E‐Skin Device

AbstractThe colloidal dispersion in a nonpolar medium is an essential material for electrophoretic displays (EPD) with low‐power consumption. A uniform‐sized superparamagnetic iron oxide nanoparticle (SPION) is a promising candidate for EPD, which exhibits tunable structural color by Bragg diffraction. In this study, the surface of SPION is charged in a nonpolar medium by inverse micelles of Solsperse‐17k, an oil‐soluble polymeric surfactant. A photonic ink of SPION dispersion exhibits simultaneous magnetochromism and electrochromism. The photonic ink is encapsulated via a complex coacervation process, in which double layers of gelatin/gum Arabic form a stable shell for µ‐capsule. The µ‐capsules show tunable structural colors, which depends upon the size of SPION in photonic ink. The increased surfactant content in photonic ink brings about a decrease in µ‐capsule size due to a reduced surface tension. A lowered gelatin concentration during coacervation results in a smaller µ‐capsule, which exhibits an electrical color tunability. Optical characterization using a confocal microscopy enables 3D visualization of the inner structure of µ‐capsules and the formation of particle chain structure of SPION in H‐field. The encapsulated photonic ink exhibits magnetochromism for 1 year, illuminating the long‐term stability of µ‐capsules developed in this study.

Production and Characterization of Colon Targeted pH Sensitive Macrospheres and Investıgation of Release Kinetics

The gastrointestinal track has different pH values at different sections. Thus, it is not easy to carry a drug to the colon for absorption. pH sensitive polymeric macrosphere drug carriers have important advantages such as being able to be taken orally, targeting the active ingredient to the desired area and dosing the active ingredient at the desired concentration for a long time in the target area. In this contex pH sensitive sodium alginate-gelatin macrospheres were produced by the dispersion phase gelling and cross-linking (complex coacervation) process method then loaded with Sternbergia lutea extract in this study. The macrosphere extract release kinetics were investigated for different pH medias that simulates different sections of the gastrointestinal track. As a result, the produced drug carrier macrospheres released the active ingredient at the colon pH (pH 7.0) while at lower pH values did not show a significant extract release. Therefore, it was reported that the produced macrospheres have potential to be used for colon diseases treatments.

Complex coacervation and freeze drying using whey protein concentrate, soy protein isolate and arabic gum to improve the oxidative stability of chia oil.

Chia oil (CO) is popular for being the richest vegetable source of α-linolenic acid (60-66%). However, this content of polyunsaturated fatty acids(PUFA) limits the incorporation of bulk CO in food products due to its high probability of oxidation. This justifies the study of alternative wall materials for microencapsulation. No reports regarding the use of dairy protein/vegetable protein/polysaccharide blends as wall material for the microencapsulation of CO have been published. Therefore, this work analyzed the behavior of a whey protein concentrate (WPC)/soy protein isolate (SPI)/arabic gum (AG) blend as wall material. The complex coacervation (CC) process was studied: pH, 4.0; total solid content, 30% w/v; WPC/SPI/AG ratio, 8:1:1 w/w/w; stirring speed, 600 rpm; time, 30 min; room temperature. The oxidative stability index (OSI) of CO (3.25 ± 0.16 h) was significantly increased after microencapsulation (around four times higher). Furthermore, the well-known matrix-forming ability of AG and WPC helped increase the OSI of microencapsulated oils. Meanwhile, SPI contributed to the increase of the encapsulation efficiency due to its high viscosity. Enhanced properties were observed with CC: encapsulation efficiency (up to 79.88%), OSIs (from 11.25 to 12.52 h) and thermal stability of microcapsules given by the denaturation peak temperatures of WPC (from 77.12 to 86.00 °C). No significant differences were observed in the fatty acid composition of bulk and microencapsulated oils. Microcapsules developed from complex coacervates based on the ternary blend represent promising omega-3-rich carriers for being incorporated into functional foods.

Development of functional textile via microencapsulation of peppermint oils: a novel approach in textile finishing

PurposeThe efforts of researchers in the 21st century have been devoted to developing novel approaches to leave planet earth green for future generations. This study aims to report the synthesis of microcapsules from natural essential peppermint oil and their application to a bleached polyester and cotton (PC) blended fabric.Design/methodology/approachMicrocapsules were prepared by a complex coacervation process and applied through the conventional pad-dry-cure method. The liquid suspension of the microcapsules was examined by optical microscopy to investigate the surface morphology of the microcapsules. Scanning electron microscopy was used to examine the surface morphology of the fabric after the application of the microcapsules. The finished fabric was checked for its mosquito repellent activity at the lab scale using a standard test protocol (cage test) by inserting a human arm and hand enfolded with microcapsules treated fabric.FindingsPC fabric treated with 6% microencapsulated peppermint oil at zero wash showed 95.3% repellency against mosquitoes, and after 30 washes, the repellency was 85.8% which confirmed the durability of the developed finished fabric. The finished samples exhibited excellent air permeabilities and absorbencies.Originality/valueThis study successfully developed peppermint oil microencapsulated fabric with excellent efficacy against three mosquito species.

Preparation and Antibacterial Properties of Carvacrol-loaded Composite Microcapsules via Palygorskite-Stabilized Pickering Emulsions

AbstractEssential oils (including carvacrol, CAR) have been used in the medicinal and health field because of their broad-spectrum antibacterial activities. However, the volatility and pungent odor are still the greatest obstacles to wider application. The purpose of the present study was to address those problems by encapsulating the antibacterial CAR in palygorskite (Plg) by integrating it into Pickering emulsions with complex coacervation. The CAR in Pickering emulsion was formed firstly by stabilization with the CAR-modified Plg; then, the emulsion droplets were embedded and fixed in the microcapsule through the subsequent complex coacervation process, which occurred between the quaternary ammonium salt of chitooligosaccharides (HACC) and sodium alginate (SA) via calcium ions. The microcapsules obtained were characterized by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The results demonstrated that the microcapsules presented a nearly sphere-like shape with a mean diameter of 3.5 mm but had a porous interior structure. The Plg plays multiple roles in the preparation process, including increasing the emulsion stability, improving the encapsulation efficiency of CAR, and the thermostability of microcapsules. The microcapsules showed remarkable antibacterial properties against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), and inhibition rates toward E. coli and S. aureus reached 100% when the microcapsules were encapsulated with 15 or 20% of CAR, respectively. The microcapsules obtained could be used as antibacterial agents in food preservatives, animal feed, and other health-related consumer products.

Microencapsulation of bromelain from pineapple extract powder by industrially scalable complex coacervation

An industrially scalable complex coacervation process (referred to as the CoCo process) enables the formation of dry complex coacervated microcapsules in one step using a low-cost spray drying approach. Here, we demonstrated the feasibility of maintaining the activity of an enzyme directly coacervated with alginates in dry powder particles by the CoCo process. As a proof of concept, bromelain, an enzyme mixture extracted from pineapple, was used to form bromelain-alginate complex coacervated (CoCo) powder. The proteolytic activity of bromelain was fully recovered from the bromelain-alginate CoCo powder, with approximately 40% of the protein coacervated with alginate. Preservation of enzyme activity by the CoCo process demonstrates the potential for scalable, cost-effective application of enzymes in foods, as well as nutraceutical, household, and industrial products.

Thermodynamic parameters of gelatin-pectin complex coacervation

Investigating the thermodynamic parameters in the formation process of protein-polysaccharide complex coacervates is very important for understanding the binding mechanism of the two biopolymers and regulating food properties by using complex coacervates. Herein, the influence of pH, salt ion strength and temperature on the thermodynamic parameters of gelatin (G)-pectin (P) complex coacervation were explored by using isothermal titration calorimetry (ITC), supplemented by dynamic light scattering and turbidity measurement. The results showed that G and P could form complex coacervates mainly through electrostatic bonding with different strength in the pH2.0–10.0. The complex coacervation process of G and P at pH 3.5 was spontaneous driven by entropy, while the binding at pH 8.5 and 9.5 was enthalpy driven. In addition, the electrostatic binding of G/P at pH 3.5 changed into an enthalpy driven process with the increase of salt ion concentration to 100 mM. Finally, the binding constant between G and P decreased with the increase of temperature from 25 °C to 45 °C, as well as positive ΔH and ΔS and negative ΔG, suggesting that the binding also involves hydrogen bonding and hydrophobic interaction. These findings could provide in-depth understanding of the application of G/P complex coacervates in the design of food structure.

Viability of microencapsulated Lactobacillus acidophilus by complex coacervation associated with enzymatic crosslinking under application in different fruit juices

The objective of this study was to produce microcapsules containing Lactobacillus acidophilus LA-02 by complex coacervation followed by crosslinking with transglutaminase and to evaluate the effect of their addition on different fruit juices, as well as the probiotic viability of L. acidophilus and its effect on fruit juices during storage. To this end, L. acidophilus was microencapsulated by complex coacervation, followed by crosslinking with transglutaminase at different concentrations. Probiotics, in their free and microencapsulated forms, were added to orange juice and apple juice at concentrations of 10% and 30%. The obtained microcapsules were characterized in terms of morphology. The viability of probiotics and the effects of their addition on fruit juices were assessed and the juices characterized (with respect to pH and total soluble solids) during 63 days of storage at 4 °C. Orange juice proved to be more suitable for the addition of probiotics, and the survival of probiotics was directly related to pH. The microcapsules had a protective effect on L. acidophilus, prolonging their survival, and the crosslinking process proved to be adequate and promising, ensuring probiotic viability. Thus, the complex coacervation process associated with induced enzymatic crosslinking provided protection for L. acidophilus in different fruit juices, showing an adequate methodology for adding probiotics to this adverse food matrix, guaranteeing the survival of L. acidophilus for up to 63 days, and generating products with innovative and promising probiotic appeal.

Microencapsulation of Vanilla Oleoresin (V. planifolia Andrews) by Complex Coacervation and Spray Drying: Physicochemical and Microstructural Characterization.

Vanilla is one of the most popular species in the world. Its main compound, vanillin, is responsible for its characteristic aroma and flavor and its antioxidant and biological properties. Vanillin is very unstable in the presence of oxygen, light, and humidity, which complicates its use and preservation. Therefore, to solve this problem, this study aimed to develop vanilla oleoresin microcapsules. Vanilla oleoresin was obtained with supercritical carbon dioxide and microencapsulated by complex coacervation and subsequent spray drying (100 °C/60 °C inlet/outlet temperature). The optimal conditions for the complex coacervation process were 0.34% chitosan, 1.7% gum Arabic, 5.29 pH, and an oleoresin:wall material ratio of 1:2.5. Fourier Transform Infrared Spectroscopy (FT-IR) analysis of the coacervates before and after spray drying revealed the presence of the functional group C=N (associated with carbonyl groups of vanillin and amino groups of chitosan), indicating that microencapsulation by complex coacervation-spray drying was successful. The retention and encapsulation efficiencies were 84.89 ± 1.94% and 69.20 ± 1.79%. The microcapsules obtained from vanilla oleoresin had high vanillin concentration and the presence of other volatile compounds and essential fatty acids. All this improves the aroma and flavor of the product, increasing its consumption and application in various food matrices.

Industrially scalable complex coacervation process to microencapsulate food ingredients

Abstract Microencapsulation by conventional complex coacervation, though highly effective and achievable at the bench-scale, is challenging to scale-up because of the complexity of the process. A novel, industrially-scalable microencapsulation process by in situ complex coacervation during spray drying (the ‘CoCo process’) is introduced, where the multiple steps are collapsed into one, to form dry complex coacervated (CoCo) microcapsules by spray drying. The CoCo process was used to encapsulate d -limonene in CoCo microcapsules using alginate and gelatin as wall materials. Insoluble CoCo particles were produced without chemical cross-linking, with extents of complex coacervation of 75 ± 6% and 64 ± 6% for CoCo particles with and without d -limonene, respectively. Up to 82.7% of d -limonene was retained during spray drying; moreover, the CoCo matrix exhibited excellent barrier properties, retaining up to 80.0% of total d -limonene over 72-day storage in sealed vials at room temperature. Industrial relevance Commercialization of microencapsulation of bioactives by complex coacervation in agricultural and food applications is hindered by the high-cost and time-intensive multistep process consisting of emulsification, coacervation, shell hardening and drying. In this work, we overcome these limitations by developing an industrially scalable in situ complex coacervation process during spray drying (‘CoCo process’). One-step complex coacervation during spray-drying opens the door to cost-effective, high-throughput, high-volume production of bioactive-containing microcapsules. The protective matrix microcapsules formed by this novel process stabilize and protect the bioactive, while allowing controlled release of the cargo for various applications in the food and many other industries.

Encapsulation optimization and pH- and temperature-stability of the complex coacervation between soy protein isolate and inulin entrapping fish oil

Fish oil presents health benefits but sensorially generates off-flavors and unpleasant odors originated from the oxidation of polyunsaturated fatty acids. To counteract this problem, microencapsulation by complex coacervation can be applied. Inulin is a prebiotic fiber, but its use in the complex coacervation process was unexplored. The objectives were to optimize the fish oil microencapsulation using soy protein isolate (SPI) and inulin as wall materials, and to determine the effect of pH and temperature on the oil retention in the microparticles. A central composite rotatable design was used, in which the inulin:SPI ratio and the amount of oil added as a function of the amount of wall materials were the independent variables. A yield of 61% and encapsulation efficiency of 94% were obtained using small amounts of inulin (inulin:SPI = 0.4) and fish oil (20%). However, the optimized microparticles were not resistant when subjected to stress of pH (5.5–6.5) and temperature (50–100 °C). Conversely, the cross-linking with transglutaminase improved the resistance of the microparticles, helping to retain more than 81% of the microencapsulated oil. These cross-linked microparticles could be suitable for food matrices that have the pH range evaluated in this study and that receive thermal treatment.

Gum Arabic and chitosan self-assembly: Thermodynamic and mechanism aspects

The interactions between gum Arabic (GA) and chitosan (CN) in solution have been investigated upon pH (4.5, 5.0 and 5.5) and temperature (5, 25 and 45 °C). Isothermal titration calorimetry (ITC) has been used to determine the thermodynamic parameters involved in the complex coacervation process between these two polymers. Zeta potential, turbidity measurements and optical microscopy were used as complementary methods to have a better understanding of the phenomenon at the origin of the self-assembly. Unlike data already published by authors, concerning the GA-CN coacervation model, a raise in temperature seemed to favor electrostatic interactions. The enthalpy became more favorable upon temperature, a phenomenon probably related to the availability of CN charges. A raise in temperature would lead to a compaction of CN, decreasing its steric hindrance during self-assembly. According to all experiments conducted in this study, the GA/CN interaction optimal molar ratio would be 4:1. However, this optimal ratio changed upon pH-temperature combinations. The results presented in this study should lead to a better understanding of the interactions between charged polymers and in the end, help in their application in the food, pharmaceutical and cosmetic industries.

Myofibrillar protein with κ- or λ-carrageenans as novel shell materials for microencapsulation of tuna oil through complex coacervation

The myofibrillar protein (MP) extracted from Ctenopharyngodon idellus was used as a novel shell material for microencapsulation of tuna oil by using the complex coacervation method in the presence of κ- or λ-carrageenan. The optimum conditions for the complex coacervation process were found to be pH 5.0 and a 4:1 ratio of MP to carrageenan (κ- or λ-carrageenan). The occurrence of complexation between the biopolymers (liquid microcapsules) was compared to the final emulsion of individual MP and confirmed by confocal laser scanning microscopy (CSLM). After spray-drying, the obtained microcapsules were analyzed in terms of morphology, size, encapsulation efficiency (EE), surface oil (SO), encapsulation yield (EY), payload (PL), moisture content, hygroscopicity, wettability, solubility, flowability, color and oxidative stability. CSLM confirmed the occurrence of complexation between the biopolymers. The morphology of the resultant microcapsules was influenced by polymer type. The average size of all microcapsules was no more than 6.0 μm with EE, SO, EY and PL ranging from 91.11 to 98.65%, 0.01–0.07%, 82.67–99%, and 41.33–49.5%, respectively. When compared to the individual MP microcapsules, the complex coacervate microcapsules were lower in hygroscopicity and wettability, but higher in moisture content and solubility. The λ-carrageenan improved the solubility of microcapsules greatly, followed by κ-carrageenan. The optimal complex coacervate microcapsules performed better in protection against oxidative deterioration during storage. This research reveals MP as a promising microencapsulating agent for microencapsulation and protection of bioactive compounds, especially with κ- or λ-carrageenan as complex coacervates.

Microencapsulation of ergosterol and Agaricus bisporus L. extracts by complex coacervation using whey protein and chitosan: Optimization study using response surface methodology

In the present work microencapsulation was applied to an ergosterol enriched extract (EEE) from Agaricus bisporus L. and pure ergosterol (PE) using a complex coacervation process. The process was optimized following two steps: (i) using response surface methodology to optimize the conditions of temperature (T, 55 to 95 °C), protein-to-chitosan ratio (P/C, 0.5 to 10.5), maximizing yield (Y1, %, w/w), efficiency (Y2, %, w/w) and load (Y3, %, w/w); and (ii) using the dose-response methodology to optimize the ergosterol content (E) at the optimal conditions achieved in (i). The global optimal conditions for both cases were the same (T of 55 °C and a P/C of 0.5), but with maximized responses of Y1 = 75.02%; Y2 = 100.00%, Y3 = 12.78%, and Y1 = 19.19%; Y2 = 100.00%, Y3 = 15.87%, respectively. The effect of increasing ergosterol content led to the reduction of the microencapsulation yield, but with an increase in the ergosterol load and maintenance of the microencapsulation efficiency.

Synthesis and characterization of microalgae fatty acids or Aloe vera oil microcapsules

Abstract It’s proposed a single methodology for the encapsulation of Aloe vera oil or microalgae fatty acids using the complex coacervation process between gelatin and gum arabic. Although a very recurrent method, it is not trivial to establish a single coacervation methodology to encapsulate different compounds. The optimal synthesis conditions, that resulted in the best yield and encapsulation efficiency, are 1:1 (m/m) wall-to-core ratio, a temperature of 40°C and agitation speed of 10,000 rpm. Optical microscopy analysis revealed that the microcapsules are spherical, have average diameters of 112 μm (A. vera) and 118 μm (microalgae) and do not form agglomerates. The microcapsules were characterized by the osmotic pressure at which they ruptured, allowing the calculation of their mechanical resistance, which resulted in 392 MPa (A. vera) and 425 MPa (microalgae). The presented optimized methodology to encapsulate both compounds aims to contribute to their efficient and rational use, especially in cosmeceutical applications.