Evaluation of different emulsification methods in double emulsion systems: Response surface optimization approach and emulsion properties

Fabrication of gelatin-EGCG-pectin ternary complex stabilized W/O/W double emulsions by ultrasonic emulsification: Physicochemical stability, rheological properties and structure

In this study, the droplet size distribution, rheological properties, and stability of dairy cream-based emulsions homogenized with different sucrose fatty acid ester (SFAE, a non-ionic small-molecule emulsifier) concentrations (0.08%, 0.16%, and 0.24% w/w) at different homogenization pressures (10 MPa and 20 MPa) were examined. Homogenization at a high pressure resulted in a smaller droplet size and narrower droplet size distribution. The D[4,3] (volume-weighted mean) and D[3,2] (surface-weighted mean) values of the emulsions decreased with an increase in the SFAE concentration. The flow properties of the emulsions homogenized with SFAE showed shear-thinning (n=0.21–0.46) behavior. The apparent viscosity (ηa,10) and consistency index (K) of the homogenized emulsions were lower than those of the control sample that is non-homogenized and without SFAE, and decreased with an increase in SFAE concentration. The storage modulus (G') and loss modulus (G") of all emulsions homogenized with SFAE were also lower than those of the control sample. The stability of all emulsions with SFAE did not show any significant change for 30 d at 5°C. However, the emulsions stored at 40°C were unstable over the storage period. Therefore, the addition of SFAE enhanced the stability of dairy cream emulsions during storage at refrigeration temperature (5°C).

Thus far, the focus of research has been on employing perilla seed protein isolate (PSPI) to stabilize emulsions encapsulating hydrophobic substances, but there is a dearth of studies focusing on PSPI-stabilized double emulsions for encapsulating hydrophilic materials. This experiment investigated the environmental stability (thermal, ionic strength, and freeze-thaw stability) of PSPI-stabilized double emulsions encapsulating anthocyanins. During thermal stability experiments, the emulsion color lightened as the treatment temperature increased, whereas the microstructures of the emulsions exhibited no notable differences among the groups. The anthocyanin retention and antioxidant capacity decreased with increasing thermal treatment temperature. After thermal treatment, no creaming or separation was observed, and anthocyanin retention remained above 65% in all groups. Ionic strength exerted a certain influence on the stability of the emulsions, with droplet size increasing and anthocyanin retention dwindling as ionic strength intensified. At an ionic strength of 100 mmol/L, anthocyanin retention surpassed 70%. No delamination was observed at any of the ionic strengths. With the augmentation of freeze-thaw cycles, the emulsions darkened and yet remained unseparated, droplet size progressively increased, and anthocyanin retention progressively decreased. The findings indicate that the emulsions were environmentally stable and could serve as a reference for the development of related emulsions.

Extraction of Ethylparaben by emulsion liquid membrane: Statistical analysis of operating parameters

Double emulsions (W/O/W) with compartmentalized structures have attracted a lot of research interests due to their diverse applications in the food industry. Herein, oil phase of double emulsions was gelled with beeswax (BW), and the effects of BW mass ratios (0–8.0%) on the stability, oral sensation, and flavor release profile of the emulsions were investigated. Rheological tests revealed that the mechanical properties of double emulsions were dependent on the mass ratio of BW. With the increase in BW content, double emulsions showed a higher resistance against deformation, and lower friction coefficient with a smoother mouthfeel. Turbiscan analysis showed that the addition of BW improved the stability of double emulsions during a 14 days’ storage, under freeze–thawed, and osmotic pressure conditions, but it did not improve the heating stability of double emulsions. The addition of BW contributed to lower air-emulsion partition coefficients of flavor (2,3-diacetyl) compared to those without the addition of BW at 20 °C and 37 °C, respectively. Furthermore, the addition of BW and its mass ratio significantly altered the flavor release behavior during the open-bottle storage of double emulsions. The response value of 0% BW dropped sharply on the first day of opening storage, showing a burst release behavior. While a slow and sustained release behavior was observed in double emulsions with 8.0% BW. In conclusion, gelation of the intermediate oil phase of double emulsions significantly enhanced the stability of double emulsions with tunable oral sensation and flavor release by varying the mass ratio of beeswax.

“Pitanga” leaf hydroethanolic extract (PLHE) presents high antioxidant and antimicrobial activities. The encapsulation of this extract in W/O/W double emulsions could protect its bioactive properties. The objective of this research was to encapsulate PLHE in the inner W phase of a double emulsion and analyze the emulsifiers concentrations and phase ratios effects on its droplet size and the physical stability. Moreover, the double emulsion rheological behavior, antioxidant and antimicrobial activities in their more stable formulation was investigated. For comparison purpose, antioxidant and antimicrobial activities of the PLHE was also determined. Overall, the droplet size and stability were affected by the concentration of emulsifiers and phase ratios. The double emulsion presented heterogeneous droplet size, good physical stability and non-Newtonian behavior. PLHE presented high antioxidant and antimicrobial activities, which was maintained after processing to encapsulation into double emulsion. In conclusion, it was possible to produce active and stable double emulsion loaded with PLHE.

The research successfully produced stable nanoemulsions by incorporating nonionic emulsifiers and environmentally friendly natural waxes. The primary focus of the study was to investigate the specific contributions of nonionic emulsifiers toward enhancing the stability of emulsions. The examination of emulsion properties in the study sheds light on how both formulation and processing methods impact the overall characteristics of the emulsions. The process of natural wax formation in the study involved using a mixture containing 10 wt% of natural wax, and 12 wt% of a complex emulsifier with a hydrophilic-lipophilic balance (HLB) value of 9.86. The emulsification was carried out at a temperature of 95 °C, with a stirring speed of 900 r/min, and an emulsification time of 10 min. The wax emulsion is stabilized by a nonionic emulsifier that creates a protective film at the interface between the water and wax. This film effectively prevents the two substances from separating, thus maintaining the stability of the emulsion. The amount of nonionic emulsifier in the interfacial film can be changed by adjusting the HLB value, the ratio of emulsifier, and the ratio of natural wax. In this way, the thickness and area of the interfacial film can be varied to regulate the particle size, zeta potential, and viscosity of the emulsion. When only the emulsification process is adjusted, the properties of the emulsion have the same trend.

Stability and release properties of double emulsions for food applications

Food emulsifiers based on milk fat globule membranes and their interactions with calcium and casein phosphoproteins

Ultrasound-assisted emulsification is an emerging technology as it provides several advantages over conventional emulsification methods. Oil–water emulsions are generally designed to encapsulate, protect, and deliver oil-soluble functional ingredients while double emulsions are used to deliver both water-soluble and oil-soluble functional ingredients simultaneously. Poor stability and less encapsulation efficiency are the main challenges associated with the double emulsification process. Ultrasound can be used as an efficient technology to obtain more stable primary and double emulsions with desired emulsification properties under control processing conditions. This review discusses the factors affecting the properties of milk protein-stabilized primary and double emulsions under sono-emulsification.

Stability, microstructural and rheological properties of complex prebiotic emulsion stabilized by sodium caseinate with inulin and konjac glucomannan

The effects of six different polyglycerol esters of fatty acids (PGEs) and two different particle sizes produced using various processing parameters on the physicochemical properties and stability of the β-carotene emulsions during digestion in simulated gastric fluid (SGF) were investigated. β-Carotene emulsions were prepared by high-pressure homogenization using β-carotene (0.1% w/w) in soybean oil as the oil phase and 1% (w/w) PGE in Milli-Q water as the water phase. The particle size of β-carotene emulsions was measured by a laser diffraction technique, and the stability of emulsions was interpreted in terms of the increase in particle size and span value of emulsion droplets and the retention of β-carotene during digestion in SGF. The average particle size ranges of emulsions were 0.17 to 0.27 μm for fine emulsions and 1.16 to 1.59 μm for coarse emulsions. In the prepared β-carotene emulsions, the particle size decreased with increasing polymerization of the glycerol in PGEs, and the higher polymerization of the glycerol also increased the stability of emulsions during digestion in SGF. Although the β-carotene content in the emulsions significantly decreased with increasing digestion period, loss of β-carotene was more severe in unstable emulsions than in stable emulsions, suggesting that the particles incorporated into droplets could provide some protective barrier for decreasing the β-carotene degradation. Therefore, β-carotene emulsions stabilized by PGEs with high polymerization of the glycerol may be useful for further applications in food and drug formulations. Decaglycerol monooleate (MO750) was demonstrated to be the most effective emulsifier in stabilizing β-carotene emulsions in this study.

Design and process optimisation of double emulsions loaded with casein hydrolysate

Summary Modified plant protein may be used as a healthy and more functional emulsifier in food products. The objective of this study was to evaluate the emulsifying properties of functionally enhanced pea protein (i.e. pea protein conjugated with guar gum, G‐PPI) and its potential application to mayonnaise, compared with unmodified pea protein. Emulsions containing G‐PPI were prepared at different pH, salt concentrations, protein concentrations and oil/water ratios. Mayonnaise samples were prepared using the pea proteins or egg yolk powder. Various characteristics of the emulsions, including droplet size, apparent viscosity, viscoelasticity and microstructure, were analysed. The emulsions with G‐PPI had significantly increased stability of up to 89.4% and apparent viscosity of up to 48.62 mPa.s. The G‐PPI emulsion had a smaller average droplet size of 934.4 nm at pH 7 compared with the PPI emulsion (stability 62.7%, apparent viscosity 22.8 mPa.s and droplet size 1664.8 nm). The pH, NaCl concentration, protein concentration and oil/water ratio greatly affected the emulsifying properties. The G‐PPI mayonnaise at higher protein concentrations (6 or 8%) exhibited excellent emulsifying and rheological properties. The modified pea protein through the green modification process with natural polysaccharides could be used as a safe and functional emulsifier in different emulsified foods.

Particle-stabilized emulsion systems, namely Pickering emulsions have recently emerged as novel yet attractive dosage form for controlled delivery of biologically active compounds. The stability and properties of emulsions are influenced by formulation and processing factors. In this study, oil-in-water Pickering emulsions were prepared using Fe3 O4 @cellulose nanocrystal (MCNC) nanocomposites and the effects of CNC/Fe3 O4 (CNC/MNP) ratios, MCNC particle concentration Cmcnc, oil volume fraction φoil and ionic strength on the colloidal stability were evaluated. The results showed that stable emulsions could be attained using MCNC particles with CNC/MNP ratio ≤ 1. Increasing CNC/MNP ratio > 1 resulted in different degree of phase separation of emulsions. The average droplet size of MCNC-stabilized Pickering emulsions (MCNC-PE) decreased from 17.34 to 3.58 µm with an increase in Cmcnc as a result of improved coalescence stability due to higher droplet surface coverage Smcnc by MCNC particles. An increase in φoil led to pronounced increase in droplet size from 2.82 to 17.00 µm. Interestingly, the ionic strength showed little or no impact on the emulsion droplet size and creaming. The storage stability study revealed that most emulsions remained fairly stable with no apparent change in droplet size. In conclusion, the physical stability of MCNC-PE was found to be greatly influenced by particulate emulsifier concentration and oil loadings. These two parameters must be well controlled in the development of Pickering emulsions for potential food and pharmaceutical applications.