Development of Stable Pickering Emulsions with TEMPO-Oxidized Chitin Nanocrystals for Encapsulation of Quercetin

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.

Corn Stover-derived nanocellulose and lignin-modified particles: Pickering emulsion stabilizers and potential quercetin sustained-release carriers

Pickering emulsions (PEs) have wide applications in delivering nutraceuticals. However, the impact of extracting nanocellulose from corn stover on stabilizing PEs and delivering nutraceuticals remains unclear. In this study, four types of nanocellulose, cellulose nanocrystals (CNC), cellulose nanofibers (CNF), lignin-containing cellulose nanocrystals (LCNC), and lignin-containing cellulose nanofibers (LCNF) were successfully prepared from corn stover, an agricultural waste. Among them, LCNC and LCNF exhibited stable reticulated microstructures, lower crystallinity, and excellent thermal stability. Besides, lignin enhanced the nanoparticles' hydrophobicity, promoting the formation of more ideally amphiphilic particles, resulting in denser emulsions at the oil-water interface. Furthermore, emulsions stabilized by LCNC and LCNF demonstrated remarkable resistance to quercetin degradation under UV light exposure (with residual level exceeding 90 %) and improved quercetin's bioaccessibility during the in vitro digestion tests, achieving the highest bioaccessibility of 48.3 %. This study provided an innovative perspective on utilizing stover-derived materials for stabilizing PEs and delivering lipophilic nutrients.

Effects of charge state of nano-chitin on the properties of polyvinyl alcohol composite hydrogel

The present work investigates the effects of nano-chitin with different charge, obtained by acid hydrolysis and TEMPO oxidation, on the structure and properties of borax crosslinked polyvinyl alcohol (PVA) hydrogels. In detail, nano-chitin prepared by acid hydrolysis (ACh) is positively charged (+28.8 mV). The electrostatic attraction between ACh and borax ions leads to a maximum tensile stress of composite hydrogel (ACh/PB), 54.25 KPa, 17 times of the borax crosslinked PVA (PB). In contrast, nano-chitin prepared by TEMPO-oxidation (TCh) shows negative charge (-59.0 mV). Due to the electrostatic repulsion with borax ions, the maximum tensile stress of composite hydrogel (TCh/PB) is only 9.25 KPa, a very limit reinforcing effect. However, TCh/PB showed better self-healing efficiency (96.0 %) as well as ionic conductivity (1.25 × 10-5 S/m). The present work shows that the charge state of the nano-chitin exerts great influence on the interaction with the crosslinking agent borax, therefore, affects the structure and properties of the final PVA composite hydrogels. The results could provide important information about making full use of nano-chitin as a reinforcement by adjusting its surface charge state.

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.

Pickering Emulsion Stabilized by Hordein-Whey Protein Isolate Complex: Delivery System of Quercetin

As a lipophilic flavonol, quercetin has low bioavailability, which limits its application in foods. This work aimed to prepare a hordein-based system to deliver quercetin. We constructed hordein-whey isolate protein fibril (WPIF) complexes (H-Ws) by anti-solvent precipitation method at pH 2.5. The TEM results of the complexes showed that spherical-like hordein particles were wrapped in WPIF clusters to form an interconnected network structure. FTIR spectra revealed that hydrogen bonds and hydrophobic interactions were the main driving forces for the complex formation. H-W1 (the mass ratio of hordein to WPIF was 1:1) with a three-phase contact angle of 70.2° was chosen to stabilize Pickering emulsions with oil volume fractions (φ) of 40-70%. CLSM images confirmed that the oil droplets were gradually embedded in the three-dimensional network structure of H-W1 with the increase in oil volume fraction. The emulsion with φ = 70% showed a tight gel structure. Furthermore, this emulsion exhibited high encapsulation efficiency (97.8%) and a loading capacity of 0.2%, demonstrating the potential to deliver hydrophobic bioactive substances. Compared with free quercetin, the bioaccessibility of the encapsulated quercetin (35%) was significantly improved. This study effectively promoted the application of hordein-based delivery systems in the food industry.

Preparation and Characterization of a Novel Natural Quercetin Self-Stabilizing Pickering Emulsion

In contrast to their well-known physiological properties, phytochemicals, such as flavonoids, have been less frequently examined for their physiochemical properties (e.g., surface activity). A natural quercetin self-stabilizing Pickering emulsion was fabricated and characterized in the present study. The antisolvent precipitation method was used to modify quercetin (in dihydrate form), and the obtained particles were characterized by light microscope, atom force microscope, XRD, and contact angle. The antisolvent treatment was found to reduce the particle size, crystallinity, and surface hydrophobicity of quercetin. We then examined the effects of the antisolvent ratio, particle concentration, and oil fraction on the properties of the quercetin particle-stabilized emulsions. In addition, increasing the antisolvent ratio (1:1~1:10) effectively improved the emulsification performance of the quercetin particles. The emulsion showed good storage stability, and the particle size of the emulsion decreased with the rising particle concentration and increased with the rising oil phase ratio. The findings indicate that natural quercetin treated with antisolvent method has a good ability to stabilize Pickering emulsion, and this emulsion may have good prospective application potential for the development of novel and functional emulsion foods.