Particle-stabilized Pickering Emulsions Research Articles

Octenyl succinic anhydride tigernut starch: Structure, physicochemical properties and stability of curcumin-loaded Pickering emulsion

In recent years, there has been increasing attention to starch particle-stabilized Pickering emulsions. In this study, the tigernut starch (TNS) was isolated from the tigernut meal, and further octenyl succinic anhydride tigernut starch (OSATNS) was prepared by a semi-dry method. The structure of OSATNS was analyzed and characterized by degrees of substitution (DS), contact angle, SEM, and FTIR. OSATNS was then used to stabilize the curcumin-loaded Pickering emulsion to improve the water solubility and stability of the curcumin. The results showed that OSATNS with 3 %–9 % OSA exhibited a DS range of 0.012 to 0.029, and its contact angle increased from 69.23° to 84.76°. SEM revealed that TNS consisted of small starch particles averaging 7.71 μm, and esterification did not significantly alter their morphology or size. FTIR analysis confirmed successful OSA incorporation by revealing two new peaks at 1732 cm−1 and 1558 cm−1. After 7 days of storage, Pickering emulsions stabilized with OSATNS-9 % exhibited superior stability and curcumin retention compared to Tween 80 emulsions, maintaining retention rates above 80 % even after different heat treatments. In conclusion, this study shows the potential application of OSATNS in stabilizing Pickering emulsions and demonstrates its good thermal stability and protection against curcumin during storage.

Pickering emulsion co-delivery system: Stimuli-responsive biomineralized particles act as particulate emulsifiers and bioactive carriers

Pickering emulsions provide a promising platform for the efficient delivery of bioactive. However, co-delivery of fragile bioactives with different physicochemical properties for comprehensive effects still faces practical challenges due to the limited protection for bioactives and the lack of stimuli-responsive property for on-demand release. Herein, a stimuli-responsive co-delivery system is developed based on biomineralized particles stabilized Pickering emulsions. In this tailor co-delivery system, hydrophilic bioactive (pepsin) with the fragile structure is encapsulated and immobilized by biomineralization, the obtained biomineralized particles (PPS@CaCO3) are further utilized as emulsifiers to form O/W Pickering emulsions, in which the hydrophobic oxidizable bioactive (curcumin) is stably trapped into the dispersed phase. The results show that two bioactives are successfully co-encapsulated in Pickering emulsions, and benefiting from the protection capacities of biomineralization and Pickering emulsions, the activity of pepsin and curcumin shows a 7.33-fold and 144.83-fold enhancement compared to the free state, respectively. Moreover, In vitro study demonstrates that Pickering emulsions enable to co-release of two bioactives with high activity retention by the acid-induced hydrolyzation of biomineralized particles. This work provides a powerful stimuli-responsive platform for the co-delivery of multiple bioactive compounds, enabling high activity of bioactives for the comprehensive health effects.

Effects of different solid particle sizes on oat protein isolate and pectin particle-stabilized Pickering emulsions and their use as delivery systems

Oat protein isolate (OPI)/high methoxyl pectin (HMP) complexes (OPP) were prepared to stabilized Pickering emulsions and applied as nutraceutical delivery systems. The different mass ratios and pH changed the interactions between OPI and HMP that caused the different size of OPP. Specifically, smaller particle size of OPP (125.7–297.6 nm) were formed when hydrophobic interactions along with electrostatic forces predominant in OPP (OPI:HMP = 3:1, pH 4, 5). Among these particles, OPP-2 could stabilize Pickering emulsion efficiently through formation of dense interfacial film, which exhibited the highest apparent viscosity and the smallest average droplet size (23.39 μm). Moreover, OPP-2 stabilized Pickering emulsions with superior stability not only exhibited higher encapsulation efficiency of 85.63%, but also could control curcumin release in simulated gastrointestinal fluids to improve curcumin's bioaccessibility. These results verified the possibility of OPP to be a Pickering emulsions stabilizer, and also identified its potential to be a stable delivery system for bioactive compounds.

Characteristics of Pickering emulsions stabilized by microgel particles of five different plant proteins and their application

Pickering emulsions stabilized by protein particles are of great interest for use in real food systems. This study was to investigate the properties of microgel particles prepared from different plant proteins, i.e., soybean protein isolate (SPI), pea protein isolate (PPI), mung bean protein isolate (MPI), chia seed protein isolate (CSPI), and chickpea protein isolate (CPI). MPI protein particles had most desirable Pickering emulsion forming ability. The particles of SPI and PPI had similar particle size (316.23 nm and 294.80 nm) and surface hydrophobicity (2238.40 and 2001.13) and emulsion forming ability, while the CSPI and CPI particle stabilized emulsions had the least desirable properties. The MPI and PPI particle stabilized Pickering emulsions produced better quality ice cream than the one produced by SPI particle-stabilized emulsions. These findings provide insight into the properties of Pickering emulsions stabilized by different plant protein particles and help expand their application in emulsions and ice cream.

In vitro digestion and colonic fermentation characteristics of media-milled purple sweet potato particle-stabilized Pickering emulsions.

Pickering emulsions stabilized by multicomponent particles have attracted increasing attention. Research on characterizing the digestion and health benefit effects of these emulsions in the human gastrointestinal tract are quite limited. This work aims to reveal the digestive characteristics of media-milled purple sweet potato particle-stabilized Pickering emulsions (PSPP-Es) during in vitro digestion and colonic fermentation. The media-milling process improved the in vitro digestibility and fermentability of PSPP-Es by reaching afree fatty acids release rate of 43.11 ± 4.61% after gastrointestinal digestion and total phenolic content release of 101.00 ± 1.44 μg gallic acid equivalents/mL after fermentation. In addition, PSPP-Es exhibited good antioxidative activity (2,2-diphenyl-1-picrylhydrazyl and ferric reducing antioxidant power assays), α-glucosidase inhibitory activity (half-maximal inhibitory concentration: 6.70%, v/v), and prebiotic effects, reaching a total short-chain fatty acids production of 9.90 ± 0.12 mol L-1, boosting the growth of Akkermansia, Bifidobacterium, and Blautia and inhibiting the growth of Escherichia-Shigella. These findings indicate that the media-milling process enhances the potential health benefits of purple sweet potato particle-stabilized Pickering emulsions, which is beneficial for their application as a bioactive component delivery system in food and pharmaceutical products. © 2024 Society of Chemical Industry.

Freeze-thaw stability of Pickering emulsion stabilized by modified soy protein particles and its application in plant-based ice cream

Pickering emulsions are of great interest to the food industry and their freeze-thaw stability important when used in frozen foods. Particles of soybean isolate (SPI) were heat treated and then crosslinked with transglutaminase (TG) enzyme to produce Pickering emulsions. The protein particles produced using unheated and uncrosslinked SPI (NSPI) was used as the benchmark. The mean particle size, absolute zeta potential, and surface hydrophobicity of protein particles produced using heat treatment and TG crosslinking (at 40 U/g) SPI (HSPI-TG-40) were the highest and substantially higher than those produced using NSPI. The thermal treatment of protein particles followed by crosslinking with TG enzyme improved the freeze-thaw stability of Pickering emulsions stabilized by them. The Pickering emulsions produced using HSPI-TG-40 had the lowest temperature for ice crystal formation and they had better freeze-thaw stability. The plant-based ice cream prepared by HSPI-TG-40 particle-stabilized Pickering emulsions had suitable texture and freeze-thaw stability compared to the ice cream produced using NSPI. The Pickering particles produced using heat treatment of SPI followed by crosslinking with TG (at 40 U/g) produced the most freeze-thaw stable Pickering emulsions. These Pickering particles and Pickering emulsions could be used in frozen foods such as ice cream.

Controlled oxidation and digestion of Pickering emulsions stabilized by quinoa protein and (-)-epigallocatechin-3-gallate (EGCG) hybrid particles

In this study, we prepared Pickering emulsions stabilized by quinoa protein isolate (QPI) and (-)-epigallocatechin-3-gallate (EGCG) non-covalent hybrid particles using ultrasonic emulsification technique and demonstrated lipid oxidation and in vitro digestion process of Pickering emulsions. The interaction forces between QPI and EGCG were characterized using fluorescence spectroscopy, isothermal titration calorimetry, and Fourier transform infrared spectroscopy. Results indicated that the non-covalent QPI/EGCG hybrid particles were formed mainly via hydrophobic interactions, hydrogen bonds, and electrostatic interactions at pH 5. Then, the QPI/EGCG non-covalent hybrid particles were applied to modify the Pickering emulsion with ultrasonic homogenization. The rheological experimental results showed that the energy storage modulus (G′) was higher than the loss modulus (G″), indicating that the emulsion had solid-like properties. As a physical barrier, interfacial layer fabricated by antioxidant QPI/EGCG hybrid particles limited lipid oxidation at 60 °C for 15 days. At 37 °C, the QPI/EGCG hybrid particles stabilized Pickering emulsions with robust antioxidant interfacial structure limited the lipid digestion under simulated gastrointestinal tract (gastric, small intestine phases). Thus, EGCG and quinoa proteins were more resistant to free radical oxidation and gastrointestinal digestion with the assistance of ultrasound. It provides a basis for better development of food and drug delivery systems by fully utilizing the antioxidant properties of plant polyphenols.

In vitro gastrointestinal digestion and colonic fermentation of media-milled black rice particle-stabilized Pickering emulsion: Phenolic release, bioactivity and prebiotic potential

This is a pioneer study that investigated the digestive characteristics of Pickering emulsions stabilized by media-milled black rice particles during in vitro digestion and colonic fermentation. Free fatty acid release of the emulsions improved from 28.42 ± 3.13% to 33.68 ± 4.05% after media milling. The phenolics released from media-milled sample were close to those from unground sample. Media-milled sample exhibited higher DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging ability and α-glucosidase inhibition rate than unground sample. Media milling increased the generation of short-chain fatty acids (SCFAs) during colonic fermentation, especially acetic acid (23% improvement in media-milled sample over unground sample). It also inhibited the growth of harmful bacteria namely Escherichia Shigella and Streptococcus, and promoted the growth of beneficial bacteria including Bifidobacterium and Blautia. These findings revealed that media-milled black rice particle-stabilized Pickering emulsions possessed intrinsic bioactivity and prebiotic potentials in the gastrointestinal tract for the first time.

Pickering emulsions stabilized by soybean protein isolate/chitosan hydrochloride complex and their applications in essential oil delivery

In this work, fabrication of soybean protein isolate (SPI)/chitosan hydrochloride (CHC) composite particles stabilized O/W Pickering emulsions using soybean oil as an oil phase was optimized by examining the effects of pH, SPI/CHC mass ratio, SPI/CHC composite particle concentration and oil phase fraction on the stability of the emulsions. The results showed that under the conditions of SPI/CHC mass ratio 1:1, pH 4 and particle concentration 2 %, the SPI/CHC composite particles could stabilize the emulsions with oil phase fraction up to 80 %. At an oil phase fraction of 60 %, the emulsions had a minimum particle size. The microstructure, storage and oxidation stabilities and rheological properties of the emulsions were determined. Using this SPI/CHC composite particle-stabilized Pickering emulsion template, citrus essential oil (CEO) Pickering emulsion (CEOP) was prepared. CEOP was found to markedly inhibit two food-related microorganisms, Staphylococcus aureus and Escherichia coli. In addition, the CEOP emulsion dilution (containing 4500 μL CEO/L) not only improved the water solubility of CEO, but also effectively retarded the browning and bacterial growth of fresh-cut apple. The SPI/CHC-stabilized Pickering emulsion template constructed in this work provides a promising alternative for the delivery of antimicrobial essential oils in the food industry.

Effect of oil phases on the stability of myofibrillar protein microgel particles stabilized Pickering emulsions: The leading role of viscosity

The Pickering emulsion may be restricted in the foods owing to the unreasonable use of oils. Herein, the effect of different oil phases on the stability of myofibrillar protein microgel particles stabilized Pickering emulsions was investigated. Results showed sunflower oil Pickering emulsions with high stability have the smallest droplet size (−26.17 μm). While peanut oil Pickering emulsions have the largest droplet size (−77.00 μm) and poor emulsion stability. The fatty acid analysis showed sunflower oil had low content of saturated (15.68 %) and super-long-chain (0) fatty acids, while peanut oil had high content of saturated (23.67 %) and super-long-chain (9.02 %) fatty acids, leading to a difference in viscosity. Low viscosity was more conducive to dispersing oil droplets and inhibiting the floating and gathering of droplets, thus enhancing the emulsion stability. Therefore, the oil with low content of super-long-chain and saturated fatty acids could be suitable for preparing MMP Pickering emulsions.

Chitosan particle stabilized Pickering emulsion/interleukin-12 adjuvant system for Pgp3 subunit vaccine elicits immune protection against genital chlamydial infection in mice.

Considering the shortcomings in current chlamydia infection control strategies, a major challenge in curtailing infection is the implementation of an effective vaccine. The immune response induced by C. trachomatis plasmid encoded Pgp3 was insufficient against C. trachomatis infection, which requires adjuvant applications to achieve the robust immune response induced by Pgp3. There is increasing promising in developing adjuvant systems relying on the delivery potential of Pickering emulsions and the immunomodulatory effects of interleukin (IL)-12. Here, owing to the polycationic nature, chitosan particles tended to absorb on the oil/water interphase to prepare the optimized chitosan particle-stabilized Pickering emulsion (CSPE), which was designed as a delivery system for Pgp3 protein and IL-12. Our results showed that the average droplets size of CSPE was 789.47 ± 44.26 nm after a series of optimizations and about 90% antigens may be absorbed by CSPE owing to the positively charged surface (33.2 ± 3mV), and CSPE promoted FITC-BSA proteins uptake by macrophages. Furthermore, as demonstrated by Pgp3-specific antibody production and cytokine secretion, CSPE/IL-12 system enhanced significantly higher levels of Pgp3-specific IgG, IgG1, IgG2a, sIgA and significant cytokines secretion of IFN-γ, IL-2, TNF-α, IL-4. Similarly, vaginal chlamydial shedding and hydrosalpinx pathologies were markedly reduced in mice immunized with Pgp3/CSPE/IL-12. Collectively, vaccination with Pgp3/CSPE/IL-12 regimen elicited robust cellular and humoral immune response in mice resulting in an obvious reduction of live chlamydia load in the vaginal and inflammatory pathologies in the oviduct, which further propells the development of vaccines against C. trachomatis infection.

Milled miscellaneous black rice particles stabilized Pickering emulsions with enhanced antioxidation activity

This work attempted to obtain miscellaneous black rice particles through directly modifying black rice using media mill, and develop milled black rice particles stabilized Pickering emulsions with intrinsic antioxidation functionalities. Particle size of milled black rice particles was reduced sharply from over twenty micrometers to 773 nm after only 90 min of milling. Slight degradation of some sensitive bioactive compounds (such as cyanidin-3-glucoside) occurred during milling process. While the bound phenolics (e.g. protocatechuic acid, ferulic acid) were well retained. Milled black rice particles exhibited good free radical scavenging activity. These milled black rice particles exhibited ability to form Pickering emulsions with good storage and heating stability. Besides, these Pickering emulsions possessed enhanced lipid antioxidation. This study offers a facile strategy to develop food-grade Pickering emulsions with intrinsic antioxidant properties by directly modify black rice as complex particulate emulsifiers through media milling process.

Development of wet media milled purple sweet potato particle-stabilized pickering emulsions: The synergistic role of bioactives, starch and cellulose

Most food-grade Pickering particles nowadays are prepared using purified single-compound substances as starting materials. Fabrication of sustainable and multifunctional particles directly from raw biomass materials could avoid complexed isolation procedure, avoid use of harmful chemicals and maintain the bioactives in raw materials. Purple sweet potatoes, rich in bioactives, were used to produce purple sweet potato particles (PSPPs) via wet media milling, which effectively decreased the particle size of PSPPs from 3371 ± 109 nm to 312 ± 18 nm after 240 min of milling. And significant amounts of bioactives and their antioxidative activity were retained. Pickering emulsions (PSPP-Es) were successfully formed using PSPPs as Pickering stabilizers. These PSPP-Es exhibited good freeze-thaw and heating stability. Low pH (3–6) and strong ionic strength (150 mM–600 mM) conditions contributed to smaller droplet size (10–12 μm) and better storage stability of PSPP-Es. Besides, PSPP-Es possessed better lipid oxidative stability than Tween 80 (a low molecular weight surfactant) stabilized emulsion due to presence of intrinsic antioxidants. This work would facilitate the development of Pickering stabilizers with outstanding emulsifying ability, high food safety, and functional properties directly from whole grain materials, and widen the application of whole grain particle-stabilized Pickering emulsions in food, cosmetics and pharmaceutical industry.

Fabrication, stability and rheological properties of zein/chitosan particles stabilized Pickering emulsions with antioxidant activities of the encapsulated vit-D3

Pickering emulsions have been known to be promising candidates for encapsulating and delivering a wide range of bioactive compounds with antioxidant potentials. In this work, we formulated and characterized zein (ZN)/chitosan (CS) stabilized Pickering emulsion. The prepared emulsions were firstly characterized by droplet size after preparation and after storage for one month at room temperature as well as after the addition of prebiotic gum Arabic (GA). Rheological measurements were further carried out to see the behavior and stability of these emulsions after storage. Thereafter, vit-D3 was encapsulated, and the antioxidant activity of the emulsions system were evaluated. The results showed that no significant change in the mean droplet diameter of the emulsions was observed after storage for a month. This claim was further confirmed by their rheological measurements particularly, the emulsions prepared with ZN/CS ratio of 1:2 having 50% oil contents exhibited significant stability. GA addition caused a gradual increase in the droplet size up to some level, after which it led to complete destabilization of the emulsion. Finally, to protect and deliver, vit-D3 was successfully loaded in these emulsions. No significant difference in the DPPH radical scavenging activity of the vit-D3 encapsulated emulsions was observed, showing their capability as delivery vehicles irrespective of their composition.

The microstructure and physiochemical stability of Pickering emulsions stabilized by chitosan particles coating with sodium alginate: Influence of the ratio between chitosan and sodium alginate

The purpose of this study was to further improve the physiochemical stability of the chitosan (CS) particle-stabilized Pickering emulsion by coating with sodium alginate (SA). The effect of different mass ratios of CS and SA (1:0.5–1:2) on the microstructure, rheology and the stability of the emulsions were comprehensively evaluated by various methods such as optical microscope, scanning electron microscope, rheometer, and low-field nuclear magnetism. The multilayer emulsion with low content of SA (CS:SA = 1:0.5) presented bridging flocculation. If SA concentration was high (CS:SA = 1:1–1:2), the surface of the Pickering emulsion droplets was completely covered by the SA. At this time, multilayer emulsion droplets became stable due to strong electrostatic and/or steric repulsion. Too high SA concentration (CS:GA = 1:2) might also promote the accumulation of moisture. In addition, the CS/SA multilayer emulsion showed higher coalescence stability under different environmental treatments but its creaming stability and flocculation stability were still sensitive to pH (2, 4 and 10), temperature (4 °C and 80 °C) and ionic strength (300–500 mM). In all, the addition of the proper level SA (CS:GA = 1:1–1:2) could increase the stability of CS particle-stabilized Pickering emulsion.

Rheological investigation of clay-stabilized oil-in-water Pickering emulsions for potential reservoir applications

Particle-stabilized Pickering emulsions are attracting increasing interest in oil and gas industries due to their unique rheological properties and stability. In this work, the rheological behavior of Na-montmorillonite stabilized oil-in-water (O/W) Pickering emulsions was studied under various salinities, pHs, clay concentrations and oil volume fractions. Results suggested that the Na-montmorillonite particles form a three dimensional network in water by different particle-particle interactions under specific salinity and pH values. The emulsion rheology can be explained by such clay interactions. The clay stabilized emulsion exhibits shear thinning behavior. At moderate salinities (around 0.25–5 wt% NaCl), the emulsion possesses a high viscosity of up to 100 mPa s at a shear rate of 7 s−1. Evidence suggests that a strong three dimensional clay network which connects the oil droplets is formed. The clay-droplet network possesses enough strength to withstand significant shear force, giving the emulsion a high bulk viscosity. Both too low and too high a salinity is unfavorable for maintaining a high emulsion viscosity. The gradual breakdown of the clay network with increasing shear rate accounts for the shear thinning behavior of the emulsion. The emulsion viscosity decreases with increasing pH as the clay-droplet network is more likely to form in an acidic environment. A two dimensional diagram summarizing the impact of salinity and pH on emulsion viscosity was generated. Emulsion viscosity also increases with clay concentration, but not always increases with oil volume fraction at a fixed clay concentration. The clay-stabilized emulsion shows significant elastic behavior. The clay network formed under a range of salinities and pHs is resilient to breakdown and has the ability to reform during strain, thus giving the emulsion a high elastic modulus. Our work shows that a clay-stabilized O/W emulsion system can possess high viscosity, shear thinning rheology and elasticity at high salinities and different pH of 3.3, 4.7, 6, 8, 9.5 and 11. These properties make the emulsion a potential candidate for various reservoir applications.

Organic pigment particle-stabilized Pickering emulsions

Pickering emulsions sometimes dry to obtain macro-porous or sheet-like structural materials. However, the process through which these materials form is unknown. This work uncovers the processes through which sheet-like structural materials form in an evaporating water-in-oil Pickering emulsion. Small samples of water-in-heptane Pickering emulsions, stabilized by colored organic pigment particles, were diluted with n-heptane and allowed to evaporate quiescently on a hydrophilic glass slide under an optical microscope. The colored nature of the particles enabled direct visualization of the behavior of the particle-coated water droplets as evaporation of oil progresses without the need for added dye. Optical microscopy revealed that a sheet-like material is formed from complete coalescence of particle-coated water droplets which locks the enwrapping particle layers. Initially, the water droplets become flattened and then change from spherical to a polyhedral shape, coalescing in areas defunct of particles and locking the particle layers into a sheet-like material.

Pickering emulsions stabilized by colloidal gel particles complexed or conjugated with biopolymers to enhance bioaccessibility and cellular uptake of curcumin

The aim of this study was to investigate the fate of curcumin (CUR)-loaded Pickering emulsions with complex interfaces during in vitro gastrointestinal transit and test the efficacy of such emulsions on improving the bioaccessibility and cellular uptake of CUR. CUR-loaded Pickering emulsions tested were whey protein nanogel particle-stabilized Pickering emulsions (CUR-EWPN) and emulsions displaying complex interfaces included 1) layer-by-layer dextran sulphate-coated nanogel-stabilized Pickering emulsions (CUR-DxS+EWPN) and 2) protein+dextran-conjugated microgel-stabilized Pickering emulsions (CUR-EWPDxM). The hypothesis was that the presence of complex interfacial material at the droplet surface would provide better protection to the droplets against physiological degradation, particularly under gastric conditions and thus, improve the delivery of CUR to Caco-2 intestinal cells. The emulsions were characterized using droplet sizing, apparent viscosity, confocal and cryo-scanning electron microscopy, zeta-potential, lipid digestion kinetics, bioaccessibility of CUR as well as cell viability and uptake by Caco-2 cells. Emulsion droplets with modified to complex interfacial composition (i.e. CUR-DxS+EWPN and CUR-EWPDxM) provided enhanced kinetic stability to the Pickering emulsion droplets against coalescence in the gastric regime as compared to droplets having unmodified interface (i.e. CUR-EWPN), whereas droplet coalescence occurred in intestinal conditions irrespective of the initial interfacial materials. A similar rate and extent of free fatty acid release occurred in all the emulsions during intestinal digestion (p > 0.05), which correlated with the bioaccessibility of CUR. Striking, CUR-DxS+EWPN and CUR-EWPDxM significantly improved cellular CUR uptake as compared to CUR-EWPN (p < 0.05). These results highlight a promising new strategy of designing gastric-stable Pickering emulsions with complex interfaces to improve the delivery of lipophilic bioactive compounds to the cells for the future design of functional foods.

Multistimuli-Responsive Pickering Emulsion Stabilized by Se-Containing Surfactant-Modified Chitosan.

Particle-stabilized emulsions that can respond to external stimuli have attracted significant concerns due to their intelligent-controlled stability, whereas particle-stabilized Pickering emulsions responding to multistimuli but based on biomass have been rarely reported. Here, a multistimuli-responsive Pickering emulsion was developed using the modified chitosan as stabilizer. Due to electrostatic attraction, Se-containing anionic surfactant, sodium 11-(butylselenyl)undecylsulfate (C4SeC11S), can bind with CS at an acidic pH and form CS-C4SeC11S complexes which can further self-associate to form micrometer-sized particles with the character of partially hydrophobicity. Therefore, at pH < pKa, an oil-in-water Pickering emulsion can be formed using CS-C4SeC11S particles as stabilizers and can spontaneously respond to redox, ion, and pH. First, with the addition of oxidation, the hydrophilicity of C4SeC11S was enhanced, and thus, hydrophobic association of CS-C4SeC11S decreased, leading to the disruption of CS-C4SeC11S particles. Hence, the emulsion destabilized. The demulsification process is closely related with the dosage of oxidant and the oxidation time. Second, introduction of a competitive ion (e.g., CTAB) could break the binding between C4SeC11S and CS, leading to the disruption of particle emulsifier. Thereby, demulsification occurred. Third, with sequentially increasing/decreasing pH, the emulsion can be switched from stable to unstable and then to stable again accordingly. Such a unique pH-responsive behavior has never been discovered in other pH-responsive Pickering emulsions. All of the stimuli-responsive behaviors were reversible. Upon alternately adding oxidant/reductant, CTAB/C4SeC11S, or base/acid, the current emulsion can be reversibly switched off (destabilization) and on (stabilization). Such a Pickering emulsion may be a good candidate as a vehicle of functional ingredient.

Food-grade particle stabilized pickering emulsion using modified sago (Metroxylon sagu) starch nanocrystal

Starch nanocrystals (SNC) have become the focus of exponential growth to develop new materials that combined innovative properties and sustainability. In this study, the physicochemical properties of SNCs extracted from Sago starch and its role as a proficient Pickering emulsifier were highlighted. Round and oval-shaped Sago starch nanocrystals (Sago-SNC) were obtained by using a conventional acid hydrolysis method. Sago-SNCs produced about 25 ± 0.2% (w/w) of the total mass yield with the mean droplet diameter ranging from 25 to 100 nm. The peak-to-peak correlation of IR analysis confirmed that there was no new chemical bond formed in Sago-SNC in comparison to native sago starch. The result from the X-ray diffraction analysis showed that the SNC has a crystallinity of 45.67 ± 0.43%. Further investigation made has discovered that the physicochemical properties of Sago-SNCs including water holding capacity, swelling power, solubility, pasting profile and thermal properties were significantly changed as all amylose was removed during the hydrolysis process. For the application and stability evaluation, Pickering emulsion prepared by using 3.5% (w/v) Sago-SNC performed good stability, appearing with no sign of creaming during two months of storage at room temperature. The results demonstrated that this natural-based nanocrystal may potentially be used as a stabilizer, filler, and emulsifier for colloidal systems.