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The complexation between two oppositely charged polyelectrolytes (PE) can lead liquid-liquid (complex coacervates, CC) or liquid-solid (solid precipitates, SP) phase separations. Herein, the effect of pH (2−11) and ionic strength (I , 0.05–1.0 M KCl) on the associative interactions between chitosan (QL)-alginate (SA) and QL-Pectin (Pec), polysaccharides widely used in biotechnology field, is described. pH and I , exhibited significant effect on the structure and phase transitions by modifying the ionization degree (α), pk a , and associative interactions between PE. Onset of binding was established at pH c 9, while continued acidification (pH τ 5.8) led to simultaneous CC and SP exhibiting a maximum turbidity in both systems. At pH δ 4.0, QL-Pec showed preferably CC structures whereas QL-SA maintained the CC and SP structures. At pH ω 2, the associative interactions were suppressed due to the low ionization of Pec and SA. I (1.0 M) significantly diminished the interactions in QL-Pec due to charge screening. Molecular weight, second virial coefficient, hydrodynamic size, ionizable groups, and persistence length of polyion, influenced on the phase behavior of QL-Pec and QL-SA systems. Therefore, CC and SP are found simultaneously in both systems, their transitions can be modulated by intrinsic and environmental conditions, expanding the functional properties of complexed polysaccharides. [ABSTRACT FROM AUTHOR]

This study aimed to stabilize microcapsules with core materials of glyceryl monostearate (GMS) and octyl and decyl glycerate, and wall materials of soy protein isolates (SPI) and flaxseed gum (FG) by complex coacervation method to overcome the drawbacks of coenzyme Q10 (CoQ10). It was demonstrated by the study that the obtained microcapsules were irregular aggregates. Differential scanning calorimetry and x-ray diffraction patterns indicated that CoQ10 was entrapped inside the disordered semisolid cores of microcapsules. The CoQ10 loading and encapsulation efficiency analysis revealed that GMS and FG helped CoQ10 better encapsulated inside the microcapsules. The in vitro release curve showed a "burst" release of CoQ10 absorbed on the surface of microcapsules for the first 180 min, followed by a sustained release of the encapsulated CoQ10. GMS and FG contributed to the sustained release and the release mechanism of the microcapsules was Fickian diffusion. The in vitro simulated digestion demonstrated that the constructed microcapsules improved the bio-accessibility of CoQ10. Finally, due to the protection of GMS and FG, microcapsules had good storage stability. In conclusion, this study emphasized the potential of using new microcapsules to deliver and protect lipophilic ingredients, providing valuable information for developing functional foods with higher bioavailability. [Display omitted] [ABSTRACT FROM AUTHOR]

This study investigates the utilization of functional additives (β-carotene microcapsules) and 3D printing technology for the production of innovative surimi products. The β-carotene microcapsules were prepared using different ratios of gelatin (Ge), gum Arabic (Ara), and carboxymethylcellulose sodium (CMC). Among these ratios, the ratio of 5:5:1 (Ge:Ara:CMC) resulted in more stable microcapsules spherical structures and better environmental stability. Subsequently, different concentrations (5–20 %) of the obtained β-carotene microcapsules were added to surimi samples. As the concentration increased, there was an improvement in the gel strength of the surimi. However, no significant changes were observed when the concentration was 15 % (p > 0.05). All samples exhibited shear thinning behavior. The addition of microcapsules improved the resilience and thixotropy of surimi, making it more suitable for 3D printing applications. The inclusion of β-carotene microcapsules in surimi products not only meets the nutritional needs of consumers, but also provides valuable insights for the development of functional surimi products. [ABSTRACT FROM AUTHOR]

The complexation of carboxymethyl short-chain amylose (CSA) and hydroxypropyl trimethyl ammonium chloride chitosan (HACC) and the stability of CSA/HACC nanocomplex were investigated. Resonance light scattering (RLS), turbidity, nanoparticle size and zeta potential analyses revealed that the complex coacervation occurred between CSA and HACC. The mass ratio and pH markedly influenced the complexation behavior; CSA with a higher degree of substitution (DS0.2) altered the complexation at a lower mass ratio and pH, increasing the turbidity and RLS intensity. The results of particle size and zeta potential analyses indicated that CSA/HACC complexes possessed the good pH and ionic strength stability. In addition to electrostatic interactions, hydrogen bonding and hydrophobic effects were also determined to be involved in the complexation process using thermal titration calorimetry (ITC). Additionally, the process was spontaneous, and CSA with a higher DS showed stronger complexation ability. These results may enable the understanding of polysaccharide complex behaviors. • The complexation between CSA and HACC was governed by pH and mass ratio. • Improved DS of CSA could enhance the stability of nanocomplex. • The interaction force changes from enthalpy drive to entropy drive with pH increased. [ABSTRACT FROM AUTHOR]

The formation of complex coacervation using chitosan and octenyl succinic anhydride modified starch (OSA starch) and microencapsulation of algae oil were investigated in this study. The zeta-potential, turbidity and coacervate yield were evaluated as a function of pH and the chitosan- OSA starch mass ratio. The highest coacervate yield was achieved at pH 6.0 with a chitosan to OSA starch ratio of 1:3 (w/w). Isothermal titration calorimetry (ITC) indicated favorable affinity (Ka = 1.51 × 105 M−1) between chitosan and OSA starch. The microcapsules yielded an encapsulation efficiency (EE) in the range of 42.8 ± 0.8%- 93.1 ± 1.2%, the loading capacity ranged between 30.4 ± 2.7% and 58.3 ± 1.3%. Fourier transform infrared spectroscopy (FT-IR) spectra and scanning electron microscopy (SEM) further confirmed the microencapsulation. In comparison with the bulk oil, the microencapsulated algae oil exhibited improved oxidative stability during storage. • Stable complex coacervates were obtained by optimization of the pH values and the chitosan to OSA starch mass ratios. • Algae oil microcapsules were successfully produced using biopolymer complexes • Chitosan- OSA starch complex exhibited good encapsulation properties • Enhanced oxidative stability of the microcapsules was achieved during storage [ABSTRACT FROM AUTHOR]

Injuries related to articular cartilage are among the most challenging musculoskeletal problems because of poor repair capacity of this tissue. The lack of efficient treatments for chondral defects has stimulated research on cartilage tissue engineering applications combining porous biocompatible scaffolds with stem cells in the presence of external stimuli. This work presents the role of rat bone marrow mesenchymal stem cell (BMSC) encapsulated-novel three-dimensional (3D) coacervate scaffolds prepared through complex coacervation between different chitosan salts (CHI) and sodium hyaluronate (HA). The 3D architecture of BMSC encapsulated scaffolds (HA/CHI) was shown by scanning electron microscopy (SEM) to have an interconnected structure to allow cell-cell and cell-matrix interactions. Chondrogenic induction of encapsulated BMSCs within HA/CHI coacervates demonstrated remarkable cellular viability in addition to the elevated expression levels of chondrogenic markers such as sex determining region Y-box 9 protein (SOX9), aggrecan (ACAN), cartilage oligomeric matrix protein (COMP) and collagen type II (COL2A1) by immunofluorescence staining, qPCR and ELISA test. Collectively, HA/CHI coacervates are promising candidates for future use of these scaffolds in cartilage tissue engineering applications. [Display omitted] • Rat BMSCs were encapsulated in HA/CHI coacervates and those cells had a viability over > 84 %. • After chondrogenic induction, coacervate encapsulated BMSCs were observed as well-distributed and in a round shape. • Upregulation of COL2A1 and ACAN genes were shown both in qPCR and ELISA. • Chondrogenic proteins were detected mostly in pericellular area while BMSCs appeared as a lacunae-embedded chondrocyte. • Chondrogenic markers of coacervate encapsulated BMSCs increased with or without induction. [ABSTRACT FROM AUTHOR]

In this study, intermolecular interactions and structure formation between hemp protein isolate (HPI) and gum Arabic (GA) were investigated to unravel their complexation mechanisms. For this purpose, structural transition as a function of pH (2.0–7.0) and protein to polysaccharide ratio (HPI:GA, R = 0.5:1–13:1 w /w) was evaluated via turbidimetric analysis, ζ-potentiometry, state diagram construction and coacervate yield. It was proved that critical phase transition pH shifted to higher values with R increase, until reaching a plateau at ratio 10:1, with complexes to be formed even at pH region where both biopolymers were negatively charged. The shift of pH value, where maximum turbidity was noticed (pH opt), was well in accordance with net charge neutrality of HPI-GA mixtures found by electrophoretic mobility measurements. Maximum coacervation, occurred at ratio R = 2:1 and pH opt = 3.5, was depicted by the highest yield (92%), while morphological characteristics of liquid as well as freeze-dried HPI-GA coacervates, obtained through optical and scanning electron microscope measurements, gave a further perception of the associative processes during complex coacervation. Additionally, the molecular interactions between HPI and GA were confirmed by Fourier transform infrared spectroscopy (FTIR) revealing primarily electrostatic interactions with secondary stabilization of hydrogen bonds. Therefore, these findings could provide useful information for the development of HPI – GA coacervates as a potential bioactive encapsulation means. [Display omitted] • HPI-GA complex coacervation is highly dependent on pH and biopolymers mixing ratio. • Coacervates formation was accomplished mainly by electrostatic interactions. • Maximum coacervation was observed at mixing ratio 2:1 (w /w) and pH opt of 3.5. • Coacervates prepared at optimum conditions presented a porous microstructure. [ABSTRACT FROM AUTHOR]

A D -optimal design was employed to optimize the microencapsulation (MEC) of basil essential oil (BEO) within a biopolymer matrix using the complex coacervation technique. BEO microcapsules (BEO-MCs) obtained under the optimal conditions exhibited high yield and efficiency with 80.45 ± 0.01 % and 93.10 ± 0.18 %, respectively. The successful MEC of BEO with an average particle size of 4.81 ± 2.86 μm was confirmed by ATR-FTIR, X-RD, and SEM analyses. Furthermore, the thermal stability of BEO-MCs was assessed using TGA-DSC analysis, which provided valuable insights into the MC's thermal stability. Furthermore, the proposed model, with a high R2 value (0.99) and low RMSE (1.56 %), was the most suitable one among the tested models for the controlled release kinetics of the optimal BEO-MCs under simulated gastrointestinal conditions. The successful optimization of BEO MEC using biopolymers through the D -optimal design could be a promising avenue for food and pharmaceutical industries, providing new strategies for the development of effective products. • D- optimal design optimizes basil EO microencapsulation for high yield and efficiency. • Biopolymer-based microcapsules show promise for food and pharmaceutical industries. • Advanced analyses confirm thermal stability of basil oil microcapsules (BEO-MCs). • MATLAB model accurately predicts controlled release kinetics of optimized MCs. • Optimization process enhances properties and applicability of BEO-MCs. [ABSTRACT FROM AUTHOR]

The feasibility of 3D printing the color, aroma and shape changes of yam gel with microwave heating as stimulus and soybean protein isolate-chitosan-maltodextrin complex coacervated microcapsules rich in water-soluble betacyanin and rose essence as stimulus-response materials was discussed. The morphology of microcapsules presented irregular spherical structure, and the surface was relatively smooth and slightly concave. Microwave heating led to the gradual destruction of microcapsules in yam gel, releasing internal pigments and essence, and enhancing the redness and flavor of printed samples. The release of the water phase and oil phase of the microcapsules and the hot-spot expansion effect of the models made the 3D printed bird models bend and deform, realizing the deformation effect of "spreading of wings", which realized a three-response synchronous change in color, shape, and flavor of the printed samples within 45 s. In this study, a variety of 4D printed foods with synchronous changes in sensory characteristics were created, which increased sensory enjoyment on the basis of ensuring the nutritional needs of food. • A 4D food printing strategy was proposed which can realize the simultaneous change of multiple sensory properties. • Microcapsules containing betacyanin and rose essence were prepared. • Microwave changed the color, flavor and shape of the printed samples containing microcapsules. • Rapid changes in color, shape, and flavor were achieved within 45 s. [ABSTRACT FROM AUTHOR]

The occurrence of Maillard reaction in protein – polysaccharide coacervated microcapsules and its effects on microcapsule properties were investigated. Vitamin E microcapsules were prepared by soybean protein isolate – chitosan coacervation at 50 °C, 70 °C, or 90 °C for 12 h in the presence of maltose. Chromatic and furosine measurements revealed that Maillard reaction occurred in the microcapsules and was favored by high incubation temperatures. The three coacervation temperatures did not destroy the microcapsule structure, but improved the microencapsulation efficiency and microencapsulation yield instead. The microcapsules exhibited decreased aggregation and the increased absolute zeta potential and particle size were believed contribute to this improvement. Stability analysis demonstrated that the microcapsules possessed enhanced resistance to dissolution in water and improved storage stability than control microcapsules. It is concluded that coacervation at a temperature high enough to initiate Maillard reaction is a promising way to improve the physiochemical properties of protein – polysaccharide coacervated microcapsules. • Heating at 50 °C and higher initiated Maillard reaction in coacervated capsules. • Maillard reaction reduced microcapsule aggregation and increased particle size. • Maillard reaction led to improved microencapsulation performance. • Maillard reaction conferred enhanced stability against dissolution in water. • Maillard reaction conferred enhanced storage stability. [ABSTRACT FROM AUTHOR]

The complexation mechanism of zedo gum and cress seed gum as nutraceutical polysaccharides with gelatin (type-A and type-B) was investigated as a function of pH, Protein to polysaccharide mixing ratio and ionic strength. Turbidity measurements were performed to achieve optimum reaction conditions. Furthermore, Zeta potential measurements along with measuring complex coacervation yield were carried out to support the turbidity results. The state diagrams representing complex coacervation formation limits were obtained for each system. FTIR analysis was performed on resulted complex coacervates which confirmed the molecular interactions between each gum and gelatin. Also, the coacervate phase of the suspensions showed shear-thinning behavior according to steady-state flows and represented higher values of storage moduli at lower frequencies in frequency sweep measurements. All systems which are assessed in this study have the potential to form particles, however, the one containing gelatin type-A had better performance in terms of pH stability. • Complex coacervates were formed using zedo gum and Cress seed gum as a polysaccharide source and gelatin. • The best gum:gelatin mixing ratio of complex coacervates prepared by zedo gum, cress seed gum and gelatin were evaluated. • The optimum pH of complex coacervates prepared by zedo gum, cress seed gum and gelatin were determined. • Wider pH window of complex coacervation was observed for systems containing Gelatin type-A. • Increasing ionic strength shrank the pH window of complex coacervation. • All complex coacervates had pseudoplastic behavior. [ABSTRACT FROM AUTHOR]

Abstract Complex coacervation was achieved by mixing the lysing enzyme from T. harzianum (LYS) with polyallylamine hydrochloride (PAH). We show in this work that the study electrostatic complexes conformation can lead to the formation of dense complexes. We systematically investigated the effects of pH and the mass ratio on the structure and properties of the complex. The different transition phases (pHc, pHφ1, and pHφ2) have been determined using dynamic light scattering, zeta potential and turbidimetric measurements. The interpolymeric bonds may be ionic or physical, depending on the pH of the system. For a pH value of 4.9, the mixture system [LYS]/[PAH] gives raise the formation of coacervate droplets. The effects of temperature on the structure of coacervate droplets are studied by small angle light scattering (SALS). Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

Abstract Carboxymethyl konjac glucomannan (CMKGM) shows potential in the construction of colon-targeted delivery systems through electrostatic interaction-based techniques. Its coacervation with chitosan (CHI) was investigated as a function of degree of substitution (DS). CMKGMs displayed the same optimum coacervation conditions of pH 6.5 and mass ratio 1:1 with CHI, but the coacervate yield was positively related to their DS. The coacervation was weakened by the presence of NaCl, but was not affected in temperatures 25–75 °C and total biopolymer concentrations 0.05–0.15% (w/v). Both electrostatic interaction and hydrogen bonding were involved in the coacervation and a higher DS contributed a denser network structure, a smaller particle size, and greater elasticity. The coacervates maintained their structures in simulated gastrointestinal fluids, but could be degraded by the β-mannanase in simulated colonic fluid. Hence, CMKGMs could be used in colon-targeted and enzyme-triggered delivery systems and the delivery performance could be tailored by varying their DS. Graphical abstract Unlabelled Image Highlights • CMKGM coacervated with CHI independent of its DS. • Optimum coacervation between CMKGM and CHI occurred at pH 6.5 and mass ratio 1:1. • CMKGM – CHI coacervates could be degraded by β-glucomannase in the simulated colonic fluid. • The properties of CMKGM – CHI coacervates were closely related to the DS of CMKGM. • CMKGM could be used for the construction of colon-targeted delivery systems. [ABSTRACT FROM AUTHOR]

Abstract Complex coacervation is a highly promising microencapsulation technique that is extensively employed in pharmaceutical, food, agriculture and textile industries. The process involves the interaction of oppositely charged polyelectrolytes in aqueous form. High payload and high encapsulation efficiency (up to 99%), relatively lower cost of processing, ability to use food-grade shell materials and synthesis at ambient temperature makes coacervation an appropriate choice in food and agrochemical industries. Various works have been documented using different polymer systems and core-shell combinations. This review paper intends to summarize some of the recent advances in complex coacervation for use in the food and agriculture areas. Current status and future trends of plant proteins utilization for complex coacervation have been reviewed. It is expected that this review will be a useful resource for material scientists, food technologists and food engineers. [ABSTRACT FROM AUTHOR]

Abstract The formation of complex coacervation using fast acidification at 25 °C for 0.5 h between casein (CAS) and gum arabic (GA) was investigated by turbidity, particle size distribution (PSD), zeta potential (ZP), and Fourier transform infrared (FTIR). When the mass ratio of CAS and GA was 1:1 and the total biopolymer concentration (C T) was 0.5% (w/v), an optimum pH (pH opt) of complex coacervation was found at pH 3.5. Particle size distribution (PSD) of homogenous CAS and GA solutions, and mixture solution of CAS-GA at critical pH values revealed the association and disassociation processes during complex coacervation. Meanwhile, ZP and FTIR spectra analyses indicated that the complexation between CAS and GA was ascribed to electrostatic interaction and hydrogen bonding. The CAS-GA coacervates were characterized by X-ray diffraction (XRD), thermogravimetric analyzer (TGA), and differential scanning calorimetry (DSC). Two XRD peaks (2 θ = 8° and 23°) differing from CAS and GA indicated the characteristic of CAS-GA coacervates. Moreover, the thermal stability of CAS-GA coacervates was superior to CAS and GA below 220 °C. The good performance of CAS-GA coacervates predicts a bright future in application of food and pharmacy industries. Highlights • Complex coacervation was prepared by casein and gum arabic. • Casein-gum arabic complex coacervates were formed at pH 3.5 when casein: gum arabic ratio was 1:1. • The formation was driven by electrostatic interaction and hydrogen bonding. • The characterization of coacervates was confirmed by XRD, DSC, and TGA. [ABSTRACT FROM AUTHOR]

Co-encapsulation of acylglycerols and probiotics may improve the resistance of probiotics to adverse conditions. In this study, three probiotic microcapsule models were constructed using gelatin (GE)-gum arabic (GA) complex coacervate as wall material: microcapsules containing only probiotics (GE-GA), microcapsules containing triacylglycerol (TAG) oil and probiotics (GE-T-GA) and microcapsules containing diacylglycerol (DAG) oil and probiotics (GE-D-GA). The protective effects of three microcapsules on probiotic cells under environmental stresses (freeze-drying, heat treatment, simulated digestive fluid and storage) were evaluated. The results of cell membrane fatty acid composition and Fourier transform infrared (FTIR) spectroscopy revealed that GE-D-GA could improve the fluidity of cell membrane, maintain the stability of protein and nucleic acid structure, and decrease the damage of cell membrane. These characteristics supported the high freeze-dried survival rate (96.24 %) of GE-D-GA. Furthermore, regardless of thermotolerance or storage, GE-D-GA showed the best cell viability retention. More importantly, GE-D-GA provided the best protection for probiotics under simulated gastrointestinal conditions, as the presence of DAG reduced cell damage during freeze-drying and the degree of contact between probiotics and digestive fluids. Therefore, co-microencapsulation of DAG oil and probiotics is a promising strategy to resist adverse conditions. • GE-D-GA had a higher freeze-dried survival rate compared with GE-GA. • The presence of DAG improved the thermotolerance of probiotics microcapsules. • GE-D-GA showed higher probiotic survival rate in simulated gastrointestinal system. • GE-D-GA showed higher probiotic viability retention during storage. [ABSTRACT FROM AUTHOR]

Heteroprotein complex coacervation corresponds to the formation of two liquid phases in equilibrium induced by the interaction of two oppositely charged proteins. The more concentrated phase known as coacervate phase, has attracted interest from several fields of science due to its potential applications for example for encapsulation and delivery of bioactives. Prior such application, it is necessary to understand how the presence of small ligands affects the complex coacervation. In this work, we report on the interaction of small ligand with individual proteins β-lactoglobulin (β-LG) and lactoferrin (LF) and consequences on their complex coacervation. ANS (8-Anilinonaphthalene-1-sulfonic acid), a fluorescent probe, was used as model ligand. While ANS did not interact with β-LG, it presented two sets of binding sites with LF inducing its self-aggregation. Depending on its concentration, ANS modulated the shape of β-LG-LF macromolecular assembly. Coacervates were observed for ANS/LF molar ratio <25 against amorphous aggregates for higher ANS/LF molar ratios. A maximum loading capacity of around 40 mg of ANS per gram of LF in the formed heteroprotein coacervates was reached. [ABSTRACT FROM AUTHOR]

Electrostatic interaction between beta-lactoglobulin (β-Lg) and water-soluble fraction of Farsi gum (WSFPG) was studied under the influence of pH, β-Lg:WSFPG mixing ratio (MR) and total concentration (TC) through performing various experiments such as turbidity, particle size and zeta potential measurements. Changes in the relative viscosity during in-situ acidification were studied at various ionic strengths. Lower amounts of absorbance and sedimentation were observed by decreasing the MR. An increase in the TC increased the absorbance of complexed samples. The smallest particle sizes, obtained at a same MR (1:3), were 108 and 188 nm at TCs of 0.1 and 0.3 wt%, respectively. The decreased relative viscosity upon acidification was a proof for the wrapping phenomenon in the biopolymer mixture. A further decrease in the relative viscosity was observed at higher ionic strength. The results of this study may facilitate the rational design of functional nanoparticles in associative mixtures of β-Lg and WSFPG. [ABSTRACT FROM AUTHOR]

The interactions of fish gelatine (FG) with hyaluronic acid (HA) are studied in an aqueous environment at 25 °C by turbidimetric titration, confocal scanning laser microscopy, dynamic light scattering, zeta potentiometry, spectrophotometry with methylene blue, and construction of state diagrams. FG forms soluble complexes with HA above a boundary pH (pH φ1 ), where both biopolymers are net-negatively charged, but develop insoluble complexes as liquid-state complex coacervates below pH φ1 , where the two biopolymers are oppositely charged. The insoluble complexes are continuously aggregated with further acid titration, followed by immediate visible phase-separation when another boundary pH (pH p ) is reached. The complex formation is mainly driven by electrostatic attractions rather than hydrogen bonding or hydrophobic interactions. The complex formation is promoted by increasing FG-to-HA weight ratio or total biopolymer concentration, or at a low ionic strength, but significantly suppressed in the presence of high ionic strength. [ABSTRACT FROM AUTHOR]

The main objective of this work was to investigate the effects of polysaccharide type (gum Arabic, GA and/or carboxymethyl cellulose, CMC) and concentration (0–0.2% (w/w)) on the electrostatic interactions with β-lactoglobulin (BLG). Biopolymer interaction was studied using turbidimetric analysis, dynamic light scattering (DLS), electrophoretic mobility and relative viscosity measurements. Complexes were developed at pH values below the isoelectric point (pI) of BLG. Increasing polysaccharide concentration increased the stability of nanocomplexes through increasing the negative charges carried by complexes. The differences between GA and CMC were attributed to the polysaccharide structure (linear or branched chains), charge density and flexibility. Phase contrast optical microscopy showed that complexation was of nucleation and growth type mechanism. Relative viscosity measurements confirmed that wrapping phenomenon occurred in both associative mixtures. [ABSTRACT FROM AUTHOR]

Chia seed oil (CSO) microcapsules were produced by using chia seed protein isolate (CPI)-chia seed gum (CSG) complex coacervates aiming to enhance the oxidative stability of CSO. The effect of wall material composition, core-to-wall ratio and method of drying on the microencapsulation efficiency (MEE) and oxidative stability (OS) was studied The microcapsules produced using CPI-CSG complex coacervates as wall material had higher MEE at equivalent payload, lower surface oil and higher OS compared to the microcapsules produced by using CSG and CPI individually. CSO microcapsules produced by using CSG as wall material had lowest MEE (67.3%) and oxidative stability index (OSI = 6.6 h), whereas CPI-CSG complex coacervate microcapsules had the highest MEE (93.9%) and OSI (12.3 h). The MEE and OSI of microcapsules produced by using CPI as wall materials were in between those produced by using CSG and CPI-CSG complex coacervates as wall materials. The CSO microcapsules produced by using CPI-CSG complex coacervate as shell matrix at core-to-wall ratio of 1:2 had 6 times longer storage life compared to that of unencapsulated CSO. The peroxide value of CSO microcapsule produced using CPI-CSG complex coacervate as wall material was <10 meq O 2 /kg oil during 30 days of storage. [ABSTRACT FROM AUTHOR]

Abstract: Surface patch binding (SPB) induced mesophase separation causing complex coacervation between biopolymers: gelatin A–gelatin B, chitosan–gelatin A, chitosan–gelatin B, and, agar–gelatin B was investigated with and without salt (I =0–0.3M NaCl). SPB was induced by pH change and three characteristic pHs identified transitions in a turbidity plot: intermolecular interactions ensued at pH c , coacervation transition occurred at pH Φ and phase separation was noticed at pHprep. Associative interactions lead to formation of soluble complexes at pH c exclusively through SPB whereas the coacervation transition was driven by electrostatic binding (EB). Neither pH c nor pH Φ displayed discernible ionic strength (till 50mM) or temperature dependence, but coacervate yield reduced with increase in ionic strength. Coacervation was completely suppressed beyond 50mM NaCl. Linear combination of attractive and repulsive parts operating between a polyelectrolyte (charged rod) with a polyampholyte (dipole or point charge) was used to model the interaction potential as function of ionic strength. Relative strength of SPB vis a vis EB was used as SPB index to establish a linear relationship with zeta potential ratio of binding partners. Different phase diagrams could be constructed which clearly identified distinct interaction regimes encountered in solutions undergoing coacervation transition. [Copyright &y& Elsevier]

Abstract: Complex coacervation in exfoliated Laponite nanoplatelets and fish gelatin mixtures was studied as a function of four key parameters: pH, ionic strength, gelatin/Laponite weight ratio, and total weight. The aim was to understand how these parameters influence phase separation kinetics, composition, internal structure, and viscoelastic properties of coacervates. By careful experimental design and turbidity measurements, the optimum conditions for coacervation were obtained. Thermogravimetric analysis revealed an outstanding heat-resistance for gelatin/nanoclay coacervates. Finally, structure of the coacervate phase was characterized by oscillatory shear experiments. The storage modulus data was observed to follow a power-law behavior and it was confirmed that under the optimum conditions, the coacervate phase was dense and structured with a characteristic length scale (ξ rheol) of ∼8.25nm. Regardless of the physicochemical condition at which complexation occurred, it was shown that the equilibrium structure of the coacervates is related to the kinetics of intermediate and late stages of phase separation; as the new defined kinetics parameter K was observed to be inversely proportional to ξ rheol that quantifies the compactness of the coacervate networks. [Copyright &y& Elsevier]

Abstract: Spectrophotometric and light scattering measurements, along with optical microscopy, were used to follow the complexation and coacervation process that occur when β-lactoglobulin (BLG)/tragacanthin (T) mixed dispersions (0.3wt.% total concentration; BLG:T ratio of 2:1) were brought from pH 6 to pH 2. In addition, the coupling of slow in situ acidification of the mixture and rheometry was utilised to gain deeper insights into pH-induced structural transitions during the assembly process. The results obtained by this multi-methodological approach allowed the associative phase separation process to be parameterised in terms of a set of characteristic pH values (∼5.3, ∼4.8, ∼4.5, ∼4.15, ∼4, ∼3.8, ∼2.5) at which critical structural changes took place. Investigation of the absorbance profiles of complexed/coacervated systems as a function of time revealed that several transitions could occur at different time scales. Morphological changes in the assemblies and the subsequent formation of some flocculant substances during the late stage of process were clearly visualised using microscopy. [Copyright &y& Elsevier]

Abstract: This study aimed to investigate the pH-induced complexation of silk fibroin (SF) and hyaluronic acid (HA). SF–HA complex coacervation was investigated by monitoring turbidity of the SF–HA system under slow acidification. Gravimetric analysis was performed to determine the yield of complex coacervation and viscosity of the system was measured to study the formation of the complexes at different pH values. The influences of total biopolymer concentration and biopolymer weight ratio on complex coacervation were examined during the analyses. Formation of the complexes was evidenced by the minimum viscosity and the maximum turbidity observed in the system. SF–HA complexes were formed within the pH–window of 2.5–3.5 regardless of the total biopolymer concentration or biopolymer ratio. Complex coacervation of SF–HA showed a reversible behavior and coacervation could be handled even in excess amounts of the biopolymers, which pointed out a non-stoichiometric complexation. [Copyright &y& Elsevier]