Oppositely Charged Pickering Emulsion Co-Stabilized by Chitin Nanoparticles and Fucoidan: Influence of Environmental Stresses on Stability and Antioxidant Activity

Research progress on marine polysaccharide-based Pickering emulsions and their potential applications in the food industry

Recently, natural biopolymers have increasingly been utilized to stabilize Pickering emulsions (PEs) for food applications. The research and development of marine polysaccharides is one of the hotspots in the field of PEs due to their low-cost, non-toxicity, abundant, and sustainability. This review aims to provide a comprehensive overview of the latest advancements in marine polysaccharide-based stabilized PEs systems. We begin with an introduction to the sources of marine polysaccharides and the methods for fabricating marine polysaccharide-based PEs. Following this, we summarize the role of natural marine polysaccharides and their complexes (combined with other polysaccharides, proteins, polyphenols, fatty acids, or other particles) as particles to form and stabilize PEs. Additionally, we detail the current applications of marine polysaccharide-based PEs in food packaging films/coatings, 3D printing, encapsulation and delivery of functional food ingredients, as well as in fat substitutes. Finally, potential future developments of PEs stabilized by marine polysaccharides in the food industry are also proposed. This review will provide valuable references to promote the application of marine polysaccharide-based PEs in the food sector.

Preparation and characterization of flaxseed oil emulsions stabilized by chitosan/gelatin complexes and evaluation of oxidation stability

Flaxseed oil (FO) is a functional oil rich in polyunsaturated fatty acids with antibacterial and antioxidant properties. However, its application is limited due to poor stability and low water solubility. To enhance the physicochemical and functional properties of flaxseed oil, the flaxseed oil-in-water (O/W) emulsions stabilized by chitosan/gelatin (CS/GE) complexes were fabricated and evaluated based on their morphology, droplet size, and rheological properties. The results indicated that 3.5 wt% and 4.0 wt% of CS/GE complexes significantly enhanced the stability of the emulsion, due to the formation of a denser three-dimensional network structure at the oil-water interface by higher concentrations of the complexes. Moreover, the emulsions had no significant changes under varying temperatures or ionic strength. Furthermore, the analysis of primary and secondary oxidation products demonstrated that the emulsions stabilized by different CS/GE complexes significantly delayed oil oxidation, and the emulsion exhibited better oxidation stability than pure flaxseed oil. Among them, the flaxseed oil emulsion stabilized by 3.5 wt% CS/GE complexes showed better oxidation stability and superior free radical scavenging capabilities, with DPPH and ABTS scavenging rates of 67.77 % and 58.81 %, respectively. This work provides valuable insights into developing stable delivery systems to encapsulate and protect flaxseed oil for functional applications in the food industry.

Foamy Melamine Resin-Silica Aerogel Composite-Derived Thermal Insulation Coating

A novel class of SiO2 aerogel-based resin composite with a self-formed foamy structure and an extremely low thermal conductivity, as well as excellent fire resistance, was fabricated via a room temperature and atmospheric pressure route. The self-formed foamy structure was achieved by utilizing SiO2 aerogel particles not only as a thermal insulative functional additive filler but also as nano-sized solid particles in a Picking emulsion system, adjusting the surface tension as a stabilizer at the interface between the two immiscible phases (liquid and air in this case). The results of foamy structure analyses via scanning electron microscopy, micro-CT, and N2 adsorption-desorption isotherms validate the successful generation of a micro-scale porous structure with the enhancement of the aerogel nano-scale solid particles at the wall as a stabilizer. A combination of multiscale pores imbues the aerogel-based foamy coating with a low thermal conductivity, as well as a high cohesive strength. For the foamy coating studied, with variable emulsion/foaming agent/aerogel ratios of 1/2/x, the thermal conductivity decreases from 0.141 to 0.031 W/m·K, and the cohesive strength increases from being non-detectable to 0.41 MPa. The temperature difference, which is a direct indicator of the thermal insulation behavior of the foamy coating, can increase from 12.1 °C to 48.6 °C under an 80 °C hot plate.

Application of Pistacia atlantica Pickering emulsion-filled chitosan gel for targeted delivery of curcumin

Emulsion-filled hydrogels are a growing system in the food industry for delivering bioactive compounds. In this study, Baneh gum (BG) particles were prepared as a Pickering emulsion stabilizer for curcumin delivery. Then, BG Pickering emulsion was added to the chitosan solution (1.5%, 2.0%, and 2.5% w/w) in different Pickering emulsion (PE):hydrogel (HYD) ratios (1:3, 1:5, and 1:7) to create an emulsion-filled gel. The highest amount of Cur stability after the 3rd week of storage was observed in the sample containing 2.0% CS and a 1:7 PE:HYD ratio (97.36%). Pickering emulsion and emulsion-filled gel significantly protected the antioxidant activity of curcumin against the thermal process (p < .05). Curcumin loading in the emulsion-filled gel provided better protection against the gastric condition compared to the emulsion system. The chitosan hydrogel swells in an acidic environment, but its combination with the anionic structure of the emulsion causes a lower release of curcumin in the stomach environment, which can help the stability of curcumin in the digestive system and have a controlled release in the gastrointestinal tract.

Noncovalent interactions between biomolecules facilitated their application in food emulsions' construction: A review

The use of biomolecules, such as proteins, polysaccharides, saponins, and phospholipids, instead of synthetic emulsifiers in food emulsion creation has generated significant interest among food scientists due to their advantages of being nontoxic, harmless, edible, and biocompatible. However, using a single biomolecule may not always meet practical needs for food emulsion applications. Therefore, biomolecules often require modification to achieve ideal interfacial properties. Among them, noncovalent interactions between biomolecules represent a promising physical modification method to modulate their interfacial properties without causing the health risks associated with forming new chemical bonds. Electrostatic interactions, hydrophobic interactions, and hydrogen bonding are examples of noncovalent interactions that facilitate biomolecules' effective applications in food emulsions. These interactions positively impact the physical stability, oxidative stability, digestibility, delivery characteristics, response sensitivity, and printability of biomolecule-based food emulsions. Nevertheless, using noncovalent interactions between biomolecules to facilitate their application in food emulsions still has limitations that need further improvement. This review introduced common biomolecule emulsifiers, the promotion effect of noncovalent interactions between biomolecules on the construction of emulsions with different biomolecules, their positive impact on the performance of emulsions, as well as their limitations and prospects in the construction of biomolecule-based emulsions. In conclusion, the future design and development of food emulsions will increasingly rely on noncovalent interactions between biomolecules. However, further improvements are necessary to fully exploit these interactions for constructing biomolecule-based emulsions.

Regulation mechanism of ionic strength on the ultra-high freeze-thaw stability of myofibrillar protein microgel emulsions

The regulation mechanism of ionic strength (0-1000 mM) on the freeze-thaw (FT) stability of emulsions stabilized by myofibrillar protein microgel particles (MMP) was systematically investigated. High ionic strength emulsions (300-1000 mM) exhibited stability after five FT cycles. With ionic strength increasing, the repulsive force between particles gradually reduced, the flocculation degree (20.72 ∼ 75.60%) and apparent viscosity of emulsions gradually rose (69 ∼ 170 mPa·s), promoting the formation of protein network structures in the continuous phase. Concurrently, the interfacial proteins rearranged (18.8 ∼ 104.2 s^-1) and aggregated rapidly, facilitating the formation of a stable interface network structure, ultimately improving its stability. Besides, scanning electron microscopy (SEM) images revealed that the interfacial proteins gradually aggregated, further forming a network with the MMP in the continuous phase, allowing MMP emulsions with enhanced FT stability at high ionic strength (300-1000 mM). This study was beneficial to produce emulsion-based sauces with ultra-high FT stability.

Enhancement of infrared absorption through a patterned thin film of magnetic field and spin-coating directed self-assembly of gold nanoparticle stabilised ferrofluid emulsion

Molecular vibration signals were amplified by the gold strip gratings as a result of grating resonances and nearby electric field hotspots. Colloidal gold island films exhibit similar enhancement; however, the uneven geometrical characteristics of these films restrict the tunability of the vibrational enhancement. Infrared absorption is enhanced by regular metallic patterns such as arrays of strips fabricated using a top-down approach such as nanolithography, although this technology is expensive and difficult. The significant infrared absorption may serve as tuneable antenna sensitization to improve the sensor performance. In this article, we present a simple one-step process for fabricating optically sensitive ordered arrays of a gold nanoparticle ferrofluid emulsion in polyvinyl alcohol (PVA) using a magnetic field-directed and spin-coating self-assembly (MDSCSA) process. Techniques such as UV-visible absorption, scanning electron microscopy, and grazing-angle infrared spectroscopy were used to evaluate various parameters associated with the nanostructures. Unlike the gold strips, the chain-like features in the iron oxide nanoparticle arrays were discontinuous. The fabricated chain-like ordered arrays have been shown to increase the local field to enhance the infrared absorption corresponding to the symmetric vibration of the -CH2 (2918 cm-1) group present in PVA by ∼667% at a 45° grazing angle, as the chain thickness (CT) increased by 178%. This scalable and simple method can potentially generate low-cost patterns for antenna sensitisation.

Characterization of Physicochemical Properties of Oil-in-Water Emulsions Stabilized by Tremella fuciformis Polysaccharides

In this paper, emulsions stabilized by Tremella fuciformis polysaccharides (TFP) were prepared and the physiochemical properties were assessed. Results showed that the TFP emulsions illustrated the highest emulsifying activity (EAI) and emulsifying stability (ESI) when the concentration of TFP and oil were 0.8% and 10% (wt%). The higher pH value was in favor of the emulsifying properties, while the addition of NaCl impaired the stability, and the greater the concentration, the lower the EAI and ESI. Besides, the emulsifying and rheological properties and stability analysis were evaluated in comparison with gum arabic, pectin, and carboxymethyl cellulose emulsions. It was discovered that TFP illustrated better storage and freeze-thaw stability, which was proved by the result of zeta-potential and particle size. The rheological measurement revealed that all the emulsions behaved as pseudoplastic fluids, while TFP displayed a higher viscosity. Meanwhile, TFP emulsions tended to form a more stable network structure according to the analysis of the parameters obtained from the Herschel–Bulkley model. FTIR spectra suggested that the O-H bond could be destructed without the formation of new covalent bonds during the emulsion preparation. Therefore, this study would be of great importance for the research of emulsions stabilized by TFP as a natural food emulsifier.