Stability Of High Internal Phase Emulsions Research Articles

Development of Oleogel-in-Water High Internal Phase Emulsions with Improved Physicochemical Stability and Their Application in Mayonnaise.

Egg-free mayonnaise is receiving greater attention due to its potential health benefits. This study used whey protein isolate (WPI) as an emulsifier to develop high internal phase emulsions (HIPEs) based on beeswax (BW) oleogels through a simple one-step method. The effects of WPI, NaCl and sucrose on the physicochemical properties of HIPEs were investigated. A novel simulated mayonnaise was then prepared and characterized. Microstructural observation revealed that WPI enveloped oil droplets at the interface, forming a typical O/W emulsion. Increase in WPI content led to significantly enhanced stability of HIPEs, and HIPEs with 5% WPI had the smallest particle size (11.9 ± 0.18 μm). With the increase in NaCl concentration, particle size was increased and ζ-potential was decreased. Higher sucrose content led to reduced particle size and ζ-potential, and slightly improved stability. Rheological tests indicated solid-like properties and shear-thinning behaviors in all HIPEs. The addition of WPI and sucrose improved the structures and viscosity of HIPEs. Simulated mayonnaises (WE-0.3%, WE-1% and YE) were then prepared based on the above HIPEs. Compared to commercial mayonnaises, the mayonnaises based on HIPEs exhibited higher viscoelastic modulus and similar tribological characteristics, indicating the potential application feasibility of oleogel-based HIPEs in mayonnaise. These findings provided insights into the development of novel and healthier mayonnaise alternatives.

Freeze-thaw stability of high-internal-phase emulsion stabilized by chickpea protein microgel particles and its application in surimi.

Future applications of high-internal-phase emulsions (HIPEs) are highly regarded, but poor freeze-thaw stability limits their utilization in frozen products. This study aimed to characterize the structure of chickpea protein microgel particles (HCPI) induced by NaCl and to assess its impact on the freeze-thaw stability of HIPEs. The results showed that NaCl induction (0-400 mmol L-1) increased the surface hydrophobicity (175.9-278.9) and interfacial adsorbed protein content (84.9%-91.3%) of HCPI. HIPEs prepared with HCPI induced by high concentration of NaCl exhibited superior flocculation index and centrifugal stability, and their freeze-thaw stability was better than that of natural chickpea protein. The increase in NaCl concentration reduced the droplet aggregation and coalescence index of the freeze-thaw emulsions, diminishing the precipitation of oil from the emulsion. Linear and nonlinear rheology showed that the strengthened gel structure (higher G' values) restricted water flow and counteracted the damage to the interfacial film by ice crystals at 100-400 mmol L-1 NaCl, thus improving the viscoelasticity of the freeze-thaw emulsions. Finally, the thawing loss of surimi gel with HCPI-200 HIPE was reduced by 2.04% compared to directly adding oil. This study provided a promising strategy to improve the freeze-thaw stability of HIPEs and reduce the thawing loss of frozen products. © 2024 Society of Chemical Industry.

Synergistic effects of phosphorylation modification and protocatechuic acid copolymerization improve the physical and oxidation stability of high internal phase emulsion stabilized by perilla protein isolate

A compact antioxidant interfacial layer was fabricated by combining phosphorylation treatment with protocatechuic acid (PA) copolymerization to enhance the physical and oxidative stability of high internal phase emulsions (HIPEs) prepared using perilla protein isolate (PPI). The covalent binding between PPI and phosphate groups induced conformational changes, facilitating the interaction between PPI and PA. The formed phosphorylated PPI-PA conjugates (LPPI-PA) exhibited a reduced particle size of 196.75 nm, promoting their adsorption at the interface. HIPEs prepared by LPPI-PA conjugates showed higher storage stability due to decreased droplet size, increased interfacial protein adsorption content (90.48%), and the formation of an interconnected network within the system. Additionally, the combination of LPPI and PA anchored PA to the interface, significantly inhibiting lipid oxidation in HIPEs as evidenced by low levels of lipid hydroperoxide (30.33 μmol/g oil) and malondialdehyde (379.34 nmol/g oil). This study holds significant implications for improving the stability of HIPEs.

Lentil protein isolate (Lens culinaris) subjected to ultrasound treatment combined or not with heat-treatment: structural characterization and ability to stabilize high internal phase emulsions

This study evaluated the effect of ultrasound treatment combined or not with heat treatment applied to lentil protein isolate (LPI) aiming to enhance its ability to stabilize high internal phase emulsions (HIPE). LPI dispersion (2%, w/w) was ultrasound-treated at 60% (UA) and 70% (UB) amplitude for 7 min; these samples were subjected to and then heat treatments at 70 °C (UAT70 and UBT70, respectively) or 80 °C (UAT80 and UBT80, respectively) for 20 min. HIPEs were produced with 25% untreated and treated LPI dispersions and 75% soybean oil using a rotor–stator (15,500 rpm/1 min). The LPI dispersions were evaluated for particle size, solubility, differential scanning calorimetry, electrophoresis, secondary structure estimation (circular dichroism and FT-IR), intrinsic fluorescence, surface hydrophobicity, and free sulfhydryl groups content. The HIPEs were evaluated for droplet size, morphology, rheology, centrifugal stability, and the Turbiscan test. Ultrasound treatment decreased LPI dispersions’ particle size (∼80%) and increased solubility (∼90%). Intrinsic fluorescence and surface hydrophobicity confirmed LPI modification due to the exposure to hydrophobic patches. The combination of ultrasound and heat treatments resulted in a reduction in the free sulfhydryl group content of LPI. HIPEs produced with ultrasound-heat-treated LPI had a lower droplet size distribution mode, greater oil retention values in the HIPE structure (> 98%), lower Turbiscan stability index (< 2), and a firmer and more homogeneous appearance compared to HIPE produced with untreated LPI, indicating higher stability for the HIPEs stabilized by treated LPI. Therefore, combining ultrasound and heat treatments could be an effective method for the functional modification of lentil proteins, allowing their application as HIPE emulsifiers.

Differences in the structural properties of three OSA starches and their effects on the performance of high internal phase Pickering emulsions

The emulsifying properties of emulsions are significantly influenced by the structural properties of octenyl succinic anhydride (OSA) starch. The purpose of this work was to elucidate the effect of the structure of OSA starch on its performance as an emulsifier to stabilize Pickering high-internal-phase emulsions (HIPEs). The degrees of substitution (DS) of the three OSA starches were 0.0137, 0.0177 and 0.0236, and their degrees of branching (DB) were 13.96 %, 14.20 % and 14.32 % measured by 1H NMR, which were sequentially labeled as OSA1, OSA2, and OSA3. The OSA3 starch with higher DS and DB had a lower critical micelle concentration (CMC) (0.11 mg/mL). Its emulsification activity (EAI) and emulsion stability (ES) were 61.8 m2/g and 72.5 min, respectively, which were higher than OSA1 and OSA2 starches. The contact angle of the three OSA starches increased from 45.35° to 80.03° with increasing DS and DB. Therefore, it is hypothesized that OSA3 starches have better emulsification properties. The results of physical stability of HIPEs confirmed the above results. These results indicated that DS and DB have a synergistic effect on emulsion properties, and OSA starch with higher DS and DB values were more conducive to the construction of stable HIPEs systems.

Salt-Promoted Fibrillation of Legume Proteins Enhanced Interfacial Modulus for Stabilization of HIPEs Encapsulating Carotenoids with Improved Nutritional Performance.

The thermal acidic-treatment-induced fibrillation of legume proteins isolated from cowpea and mung bean was demonstrated to be promoted by salt. Worm-like thin prefibrilar intermediates were formed in low salt concentrations (0-75 mM), which twisted to be the thick and mature amyloid-like fibrils with multistrands as the salt content was elevated (150-300 mM). Absorption of the fibrils fabricated in high salt concentrations to the oil/water interface constructed the protein layer with a significantly higher interfacial modulus compared with the one formed by the fibrils fabricated in low salt concentrations. Consequently, they showed the superiority in stabilizing high internal phase emulsions (HIPEs) with oil volume fraction ratios higher than 74%. HIPEs stabilized by the high salt-concentration-induced legume protein fibrils had stronger capabilities not only in encapsulating liposoluble carotenoids but also in protecting their stability against heating, ultraviolet, and iron ion stimulus, compared with the one stabilized by the low-salt-concentration-induced legume protein fibrils. Bioaccessibilities of the carotenoids in simulating gastrointestinal (GI) digestion were significantly improved after encapsulation by the HIPEs, which were interestingly increased with the elevation of salt concentrations utilized for preparing the legume protein fibrils. Furthermore, the carotenoids-loading-HIPEs were injectable and showed in vivo nutritional functions of mitigating colitis.

Stability of high internal-phase emulsions prepared from phycocyanin and small-molecule sugars.

The use of high internal-phase Pickering emulsions in the food industry is widespread due to their excellent stability and special rheological properties. Proteins are often used as food-grade Pickering stabilizers due to their safety and nutritious properties. Nowadays, the development and efficient utilization of novel proteins as Pickering stabilizers has become a new challenge. Phycocyanin complexes with small-molecule sugars (SMS), formed as a result of non-thermal interactions, can serve as stabilizers for high internal-phase Pickering emulsions. The addition of SMS-enabled gel-like emulsions significantly reduced the amount of emulsifier used. When the SMS was sorbitol, the emulsion had excellent elastic properties and self-supporting ability and was stable during long-term storage, when subjected to centrifugation, and under different temperature conditions. The fluorescent property of phycocyanin was utilized to investigate the formation mechanism of the emulsion. Small-molecule sugars were able to form 'sugar-shell' structures on the surface of proteins to enhance the structural stability of proteins. Phycocyanin-SMS-stabilized emulsions provided superior protection for photosensitive and volatile substances. The retention rates of trans-resveratrol and n-hexane increased by 384.75% and 30.55%, respectively. These findings will encourage the development of proteins that stabilize Pickering emulsions. They will also provide new ideas for protecting photosensitive and volatile substances. © 2023 Society of Chemical Industry.

Stabilization of oil-in-water high internal phase emulsions with octenyl succinic acid starch and beeswax oleogel

High internal phase emulsions (HIPEs) based on beeswax (BW) oleogels and octenyl succinic acid starch (OSA starch) were prepared by a facile one-step method. Effects of the oleogelation of internal phase on the formation, stability and functionality of the HIPEs were investigated. OSA starch absorbed at the interface allowed high surface charge (|ζ| > 25 mV) of the droplets, and small droplet size (d ≈ 5 m). Microstructural observation suggested that the HIPEs were of O/W type with droplets packed tightly. With the increase in BW content (0–4 %), the particle size (4–7 μm) and ζ-potential (−25 ~ −30 mV) of the HIPEs were first decreased and then increased. Stability analysis revealed that the addition of BW effectively improved emulsion stability against centrifugation, freeze-thawing, changes in pH and ionic strength, and the HIPE with 2 % BW presented the best stability. Rheological tests indicated that the HIPEs with higher content of BW exhibited higher storage modulus, solid-like properties, and shear thinning behaviors. Creep-recovery results implied that the oleogelation enhanced the structure of HIPEs and improved the deformation resistance of the systems. When subjected to light and heat, oleogel-in-water HIPEs showed advantages in protecting β-carotene from degradation, and β-carotene in the HIPEs with 2 % BW had the lowest degradation rate. These findings suggested that gelation of oil phase could improve the stability of HIPEs and the encapsulation capability, which would be meaningful for the development of novel healthy food.

High internal phase emulsions stabilized by whey protein covalently modified with carboxymethyl cellulose: Enhanced environmental stability, storage stability and bioaccessibility

In this work, the effects of whey protein-carboxymethyl cellulose (WP-CMC) conjugates on the environmental stability, in vitro digestion stability, storage stability and bioaccessibility of high internal phase emulsions (HIPEs) were investigated. Compared to the HIPEs stabilized by the mixture of WP and CMC, the HIPEs stabilized by WP-CMC were less sensitive to environmental changes by particle size and zeta-potential, and showed better stability and bioavailability of pine nut oil as well as β-carotene during simulated gastrointestinal digestion. In addition, the inclusion function and pine nut oil oxidative stability of the HIPEs stabilized by WP-CMC were better during 16 days of storage than those of the pine nut oil and HIPEs stabilized by the mixture of WP and CMC, and also expressed higher storage stability of β-carotene. These results suggested that the conjugate-stabilized emulsions developed in this study have potential applications as protectors and carriers of liposoluble active ingredients.

The formation of rice starch/casein complex by hydrothermal and stabilizing high internal phase emulsions with 3D printing property

The high internal phase emulsions (HIPEs) are suitable for 3D printing because of their good self-supporting and shear-thinning. However, the HIPEs prepared from single unmodified casein showed bad self-supporting and could not be used for 3D printing. Therefore, the rice starch/casein complex (SC) was prepared and used in the HIPEs for 3D printing. The SC was treated at different hydrothermal temperatures (60, 80, and 100 °C), and FTIR, XRD, and DSC confirmed the formation of SC by hydrogen bonds. The DSC, apparent viscosity, and microstructure revealed the degree of gelatinization of SC, which affected the properties of the HIPEs. When the degree of gelatinization of SC increased from 12.35% to 70.62%, the HIPEs prepared from the SC treated at 100 °C for 1 h had higher storage modulus, viscosity, and three-interval thixotropy, including lower frequency dependence, which showed the desirable 3D-printing qualities, that is, easy extrusion, stable recovery, and self-supporting. The storage stability of HIPEs prepared from SC showed stable storage at low temperatures (4 °C > 25 °C). These results suggest that rice starch/casein with a higher degree of gelatinization could be used to prepare HIPEs with good 3D-printing characteristics. Furthermore, the developed HIPEs could be applied for 3D printing of foods with the personalized shape.

Extrusion-based 3D printing of pickering high internal phase emulsions stabilized by flaxseed protein-sodium alginate complexes for encapsulating curcumin

In the present work, sodium alginate-based complex (flaxseed protein-sodium alginate) electrostatic complexes (FP-AG) were fabricated, acting as an effective emulsifier for the first time to stabilize Pickering high internal phase emulsions (HIPE). Interactions between FP and AG were evaluated by isothermal titration calorimeter and quartz crystal microbalance with dissipation monitoring. These results suggested that electrostatic interactions played a dominant role in FP-AG complexation, and stronger interactions between FP and AG occurred under acidic conditions, forming more viscoelastic layers. FP-AG complexes at pH 4.0 (FP-AG4) exhibited appropriate wettability (87.9°). HIPEs were prepared using FP-AG4 (HIPE-C), contrasted with FP at pH 8.0 (HIPE-P) as a control. Rheological results suggested that HIPE-C exhibited shear-thinning behavior (extrusion), high thixotropy (recovery), and high viscoelasticity (self-supporting), which possessed a great potential for 3D printing. Moreover, 3D printing and the stability of curcumin of HIPE were explored simultaneously for the first time. These results showed that HIPE-C exhibited outstanding printability and printing models presented smooth surfaces, regular shapes, and distinct resolution. HIPE-C showed a better protection for curcumin against ultraviolet and thermal treatments than HIPE-P. FP-AG complexes could be used as an effective HIPE stabilizer and novel edible ink with good 3D printability in food industry.

Conjugation of aminated sugar beet pectin–tannic acid nanoparticles with cinnamaldehyde at the oil–water interface to stabilize a 3D printable high-internal phase emulsion

In this work, we demonstrated the use of aminated sugar beet pectin (SBP–NH2)–tannic acid (TA) nanoparticles (NPs) conjugated with cinnamaldehyde (CA) to form 3D printable high-internal phase emulsions (HIPEs). Unlike the absorption of common stabilizers, the interfacial conjugation of SBP-NH2/TA NPs with CA formed ultra-absorbed NPs at the oil–water interface through electrostatic bonding, hydrogen bonding, hydrophobic interactions, and Schiff base reaction. The addition of CA (2.5 wt%) to the oil phase significantly reduced the mean droplet size of SBP-NH2/TA NPs stabilized HIPE (75 vol% oil; SBP-NH2/TA mass ratios of 1:0.5) from 23.03 to 18.33 μm and greatly improved the stability of HIPEs during a 90-day storage period at 25 °C. Concomitantly, rheological studies indicate that HIPEs with CA had high viscoelasticity up to 3 orders of magnitude, providing HIPE-based inks with exceptional support performance and smooth extrusion features. In particular, TA and CA act as the components of a stabilizer and adsorb onto the oil–water interface, imparting combined antioxidant and antimicrobial dual capabilities to HIPEs. In the SBP-NH2/TA NPs stabilized HIPEs, the addition of CA resulted in 0.34-fold lower amounts of primary and secondary lipid oxidation products and 0.4–0.5-fold higher antimicrobial properties against either E. coli or S. aureus. This work established that the interfacial conjugation of the SBP-NH2/TA NPs with CA advanced the antioxidant and antimicrobial properties, stability, water-holding capacity, and viscoelastic properties of HIPEs. Furthermore, the three-dimensional (3D) printed structure with notable mechanical strength was achieved.

High Internal Phase Emulsions Stabilized by Pea Protein Isolate Modified by Ultrasound Combined with pH-Shifting: Micromorphology, Rheology, and Physical Stability

In this study, the interfacial behavior of high internal phase emulsions (HIPEs), stabilized by ultrasound combined with pH-shifting modified pea protein isolate (MPPI), was investigated, and its emulsification process and stabilization mechanism were discussed. The effects of MPPI concentration on the micromorphology, droplet size, rheology, and stability of HIPEs were investigated. As the MPPI concentration increased, the appearance of HIPEs gradually changed from a relatively fluid state to a plastic solid-like state with detailed texture. There occurred a gradual decrease in droplet size, the cohering of an orderly and tight arrangement, in addition to the formation of a bilayer elastic interface layer. The macro- and microrheological assessments confirmed that the apparent viscosity, storage modulus, elasticity index, and macroscopic viscosity index increased gradually. Furthermore, it was demonstrated that 5 wt% MPPI-stabilized HIPEs had the potential to be used as 3D printing inks. Stability evaluation showed that the TURBISCAN stability index decreased and centrifugal stability increased. The appearance and microstructure remained highly stable after heating at 80 °C for 30 min and storage at 4 ℃ for 90 days. These findings confirm that MPPI improves the rheological behavior and stability of HIPEs by modulating the interfacial adsorption and network structure.

Stability and release of peach polyphenols encapsulated by Pickering high internal phase emulsions in vitro and in vivo

In this work, Pickering high internal phase emulsions (HIPEs) were employed to protect peach polyphenols in vitro and vivo. Firstly, HIPEs stabilized by zein nanoparticles and gum Arabic (GA) with corn oil volume fraction of 76% were prepared. The effects of pH in aqueous phase (pH 3–7) and GA concentration (0 %–4%) on the creaming index (CI), particle size, potential, microstructure and rheology of HIPEs were analyzed. Results indicated that after GA concentration reached 2%, the stability of HIPEs kept relatively steady. With the decrease of pH in aqueous phase, the stability of HIPEs improved. Consequently, the pH 3 and 2% GA concentration were selected to prepare the stable HIPEs. Secondly, the HIPEs with corn oil dissolved peach polyphenols (PP-HIPEs) were obtained and the encapsulation rate of peach polyphenols reached 74.25%. Compared to polyphenols dissolved in water and corn oil, the stability of peach polyphenols in PP-HIPEs during UV irradiation, storage and heating significantly improved. Bioaccessibility of peach polyphenols in PP-HIPEs during simulated gastrointestinal digestion obviously enhanced and reached 60.49%. The content of polyphenols in stomach, small intestine, colon and feces in PP-HIPEs were higher, suggesting the better protection, higher adsorption and stronger potential biological activity during digestion. Meanwhile the peach polyphenols could prevent the increase of body weight caused by HIPEs. Thus, the HIPEs could be used as an excellent protective and effective delivery method for peach polyphenols during digestion.

Formulation and stabilization of high internal phase emulsions: Stabilization by cellulose nanocrystals and gelatinized soluble starch

In this work, high internal phase emulsions (HIPEs) stabilized by naturally derived cellulose nanocrystals (CNC) and gelatinized soluble starch (GSS) were fabricated to stabilize oregano essential oil (OEO) in the absence of surfactant. The physical properties, microstructures, rheological properties, and storage stability of HIPEs were investigated by adjusting CNC contents (0.2, 0.3, 0.4 and 0.5 wt%) and starch concentration (4.5 wt%). The results revealed that CNC–GSS stabilized HIPEs exhibited good storage stability within one month and the smallest droplets size at a CNC concentration of 0.4 wt%. The emulsion volume fractions of 0.2, 0.3, 0.4 and 0.5 wt% CNC–GSS stabilized HIPEs after centrifugation reached 77.58, 82.05, 94.22, and 91.41 %, respectively. The effect of native CNC and GSS were analyzed to understand the stability mechanisms of HIPEs. The results revealed that CNC could be used as an effective stabilizer and emulsifier to fabricate the stable and gel-like HIPEs with tunable microstructure and rheological properties.

Freeze-thaw stability and rheological properties of high internal phase emulsions stabilized by phosphorylated perilla protein isolate: Effect of tea saponin concentration

This study investigated the interfacial behavior of phosphorylated perilla protein isolate (LZPI) and tea saponin (TS) as co-stabilizers in high internal phase emulsions (HIPEs), and its relationship with rheological properties and freeze-thaw stability of HIPEs was further explored. The results demonstrated that the interfacial adsorption process of LZPI-TS complexes could be divided into two stages. At low concentration (0.2–1.0%, w/v), TS had synergistic effects with LZPI, and the oil-water interface was dominated by LZPI co-adsorbing TS molecules. The combination of interfacial interaction and the improvement of interfacial film strength endowed the prepared HIPEs with enhanced performance, such as decreased droplet size, strengthened inter-droplet network structure, better viscoelasticity and structure-recovery property. However, at high TS concentration (1.5–2.0%, w/v), the interfacial film was mainly dominated by TS, and some LZPI would be replaced by TS from the interface into the aqueous phase, resulting in the reduction of interfacial film strength, further reducing the droplet size and viscoelasticity of HIPEs, but effectively improving the freeze-thaw stability of the system owing to the increased viscosity of the continuous phase and the decreased amount of ice crystals formed during the freezing process. These findings confirmed that the interfacial behavior of LZPI-TS complexes was regulated by TS concentration, which was closely related to the performance and stability of HIPEs. This study had important guiding significance for revealing the interaction between protein and small molecular emulsifier, and providing technical reference for developing mayonnaise-like emulsions with good performance and excellent freeze-thaw stability. • The combination of LZPI and TS improved the strength of the interfacial film. • HIPEs containing 1.0% TS exhibited enhanced rheological properties. • The addition of 1.0–2.0% TS was beneficial for the enhancement of freeze-thaw stability of HIPEs.

OSA-linear dextrin enhances the compactness of pea protein isolate nanoparticles: Increase of high internal phase emulsions stability

The pea protein isolate nanoparticles/octenyl succinic anhydride linear dextrin (PPINs/OSA-LD) composite particles were fabricated by heating at acidic condition. Heating treatment not only made OSA-LD dissolve, but also promoted the hydrophobic interactions between PPINs and OSA-LD. With the increase of OSA-LD content, the average diameter of composite particles decreased due to the avoidance of hydrophobic aggregation between PPINs during heating, and the composite particles became more compact and regular. The high internal phase emulsions (HIPEs) stabilized by composite particles exhibited smaller droplet size, higher viscosity and modulus attributing to the formation of denser interfacial layer. The results of low field nuclear magnetic resonance proved that the HIPEs stabilized by composite particles showed more uniform distribution of water and oil. This work provided a facile method to fabricate composite particles, which had excellent capacity to stabilize the HIPEs.

Confined flow behavior under high shear rates and stability of oil/water high internal phase emulsions (HIPEs) stabilized by whey protein isolate: Role of protein concentration and pH

High shear rheometry was used to investigate the rheological behavior of high internal phase emulsions (HIPEs) stabilized by whey protein isolate (WPI). The physical stability of HIPEs was tested at extremely high shear rates generated by decreasing the gap height between parallel plates. Viscosity and yield stress, at narrow gaps, increased with protein concentration due to tighter packing of smaller droplets. Structural breakdown and recovery of HIPEs were affected by protein concentration and pH. The hysteresis behavior of HIPEs was either thixotropic or anti-thixotropic and was determined by protein concentration, whereas pH affected the magnitude of anti-thixotropy. At pH 3, emulsions showed greater stability against extreme shear and creaming due to higher deformability of oil droplets and increased interdroplet interaction compared to neutral pH. Challenging the physical integrity of concentrated emulsions under high shear is an effective way to characterize microstructural changes and stability of HIPEs in foods.

Hydrophilic macroporous monoliths with tunable water uptake capacity fabricated by water‐in‐oil high internal phase emulsion templating

AbstractIn this contribution, a series of well‐defined amphiphilic di‐block copolymers poly(ethylene oxide)‐b‐polystyrene (PEO43‐b‐PSx) with different PS segment lengths of x = 41, 78, and 130 units were synthesized through activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP). The as‐prepared block copolymers successfully stabilized the water‐in‐oil (W/O) high internal phase emulsions (HIPEs) containing pH responsive monomers 2‐(dimethylamino)ethyl methacrylate (DMAEMA) and 2‐(diethylamino)ethyl methacrylate (DEAEMA). The effect of macro‐surfactant loading, PS segment length, and DMAEMA/DEAEMA content on the stability of HIPEs and the corresponding polyHIPE structure were investigated. Results show that the average void size of polyHIPE decreases with the increase of surfactant concentration. Macroporous morphologies with closed‐cell or open‐cell can be manipulated by surfactant loading as well. The openness of polyHIPE decreases as the increase in hydrophobic PS segment length. Compared to DMAEMA containing HIPE systems, stable DEAEMA containing HIPEs are more easily obtained by using the as‐prepared macro‐surfactant. Stable HIPE with a relatively large amount of DEAEMA, up to 70 vol% of oil‐phase has been achieved. The obtained PDEAEMA‐co‐PS polyHIPEs derived from 0.116 mol% PEO43‐b‐PS41 stabilized emulsion templates show pH responsiveness towards water absorption and the highest acidic water uptake capacity can be up to 6.6 times its weight at equilibrium state. This work paves the way for the preparation of hydrophilic macroporous monolith from stable W/O HIPE template, and confirms the strength of macro‐surfactant in such an approach.

Characteristics, formation mechanism and stability of high internal phase emulsions stabilized by porcine plasma protein (PPP) / carrageenan (CG) hybrid particles

High internal phase emulsions (HIPEs) stabilized by nanoparticles based on biomacromolecules are challenging issues in recent decade. Herein, a newly developed HIPE was investigated by using heat-denatured porcine plasma protein (PPP) nanoparticles at pH 6.5 as emulsifier, and its emulsifying stability could be significantly enhanced by compounding carrageenan (CG). In the miscible system, PPP and CG formed hybrid particles through non-covalent interaction, and the sizes and zeta-potentials of the particles increased significantly along with addition of CG (from 0 to 0.7%, w/v), reached up to about 3.6 μm and −53 mV at 0.5% (w/v), respectively. CG weakened the ability of PPP to lower interfacial tension of oil/water (O/W), but increased the apparent viscosity of the system. The results from CLSM, rheology and stability experiments indicated a significant increasing trend of the HIPEs stability and solid-like characteristics along with addition of CG. Compared with the controls including bovine serum albumin (BSA), BSA-CG and CG alone, PPP-CG hybrid particles had good performance in fabricating and stabilizing the HIPEs. The work revealed the novel function of PPP as emulsifier of HIPEs and so offered the theoretical direction for application of PPP as a mass by-product, as well as an excellent HIPEs system for food, medicine and cosmetics fields.