The stabilizing effect of cellulose crystals in O/W emulsions obtained by ultrasound process

Ultrasound treatment of crystalline oil-in-water emulsions stabilized by sodium caseinate: Impact on emulsion stability through altered crystallization behavior in the oil globules

Partial coalescence is a key factor contributing to the instability of crystalline oil-in-water emulsions in products like dressings and sauces, reducing shelf life. The intrinsic characteristics of semi-crystalline droplets, including solid fat content, fat crystal arrangement, and polymorphism, play a pivotal role in influencing partial coalescence, challenging prevention efforts even with emulsifiers like amphiphilic proteins. High-intensity ultrasound (HIU) has emerged as an efficient and cost-effective technology for manipulating bulk fat crystallization, thereby enhancing physical properties. This study specifically investigates the impact of HIU treatment on fat crystallization on protein-stabilized crystalline emulsions, utilizing palm olein stearin (POSt) as the lipid phase and sodium caseinate (NaCas) as the surfactant under various HIU powers (100, 150, 200, 300, and 400 W). Results show that increasing HIU power maintained the interfacial potential (-20 mV) provided by NaCas in the emulsions without significant differences. Higher HIU power induced the most stable polymorphic form (β) in the emulsions. Engagingly, the emulsions at 200 W exhibited better storage stability and slower partial coalescence kinetics. Semi-crystalline globules had more uniform and integral crystal clusters that were distributed tangentially near the droplet boundary, perhaps attributed to intermediate subcooling (40.4 °C) at 200 W. The acoustic energy of HIU significantly translates into thermal effects, influencing subcooling degrees as a dominant factor affecting crystallisation in the emulsions. This study establishes ultrasonic crystallization as a novel strategy for modifying the stability of emulsions containing fat crystals.

Recent progress on Pickering emulsion stabilized essential oil added biopolymer-based film for food packaging applications: A review

Nowadays food safety and protection are a growing concern for food producers and food industry. The stability of food-grade materials is key in food processing and shelf life. Pickering emulsions (PEs) have gained significant attention in food regimes owing to their stability enhancement of food specimens. PE can be developed by high and low-energy methods. The use of PE in the food sector is completely safe as it uses solid biodegradable particles to stabilize the oil in water and it also acts as an excellent carrier of essential oils (EOs). EOs are useful functional ingredients, the inclusion of EOs in the packaging film or coating formulation significantly helps in the improvement of the shelf life of the packed food item. The highly volatile nature, limited solubility and ease of oxidation in light of EOs restricts their direct use in packaging. In this context, the use of PEs of EOs is suitable to overcome most of the challenges, Therefore, recently there have been many papers published on PEs of EOs including active packaging film and coatings and the obtained results are promising. The current review amalgamates these studies to inform about the chemistry of PEs followed by types of stabilizers, factors affecting the stability and different high and low-energy manufacturing methods. Finally, the review summarizes the recent advancement in PEs-added packaging film and their application in the enhancement of shelf life of food.

Low-Frequency Ultrasound Effects on Cellulose Nanocrystals for Potential Application in Stabilizing Pickering Emulsions

Cellulose, in the form of cellulose nanocrystals (CNCs), is a promising biomaterial for stabilizing Pickering emulsions (PEs). PEs are commonly formed using low-frequency ultrasound (LFU) treatment and impact CNC properties. The present study investigated the specific effects of LFU treatment on CNCs' chemical and physical properties. CNCs were characterized using dynamic light scattering, ζ;-potential determination, Fourier transform infrared spectroscopy, X-ray diffraction, and contact angle measurement. CNC suspensions were studied using rheological analysis and static multiple light scattering. LFU treatment broke CNC aggregates and modified the rheological behavior of CNC suspensions but did not affect the CNCs' chemical or crystallographic structures, surface charge, or hydrophilic properties. During the storage of CNC suspensions and PEs, liquid crystal formation was observed with cross-polarized light. Hypotheses related to the impact of liquid crystal CNCs on PE stability were proposed.

Stabilization of ginger essential oil Pickering emulsions by pineapple cellulose nanocrystals

Pickering emulsions (PE) are systems made up of two incompatible fluids, these are stabilized by solid organic or inorganic particles located on their interface. Cellulose nanocrystals (CNCs) are sustainable and biocompatible value-added naturally occurring biomolecules which are being investigated as PE stabilizers in the cosmetic, food, and pharmaceutical industries. The objective of this research was to investigate the efficacy of pineapple cellulose nanocrystals as stabilizers for a ginger essential oil-in-water Pickering emulsion. Anionic pineapple cellulose nanocrystals were prepared by acid hydrolysis. Ginger essential oil-in-water emulsions were prepared by ultrasonication. Pineapple CNC produced stable Pickering emulsions with surface average droplet size of 4.3 μm-6.2 μm, high negative zeta potential, high viscosity, and high adsorption at the interface. Pickering emulsions by ultrasonication were stable against droplet coalescence, phase separation, and droplet flocculation for at least 8 weeks at 25 °C or 40 °C at various droplet sizes. The emulsion droplet size and volume density (droplet size distribution) were evaluated by varying the particle concentration (CNC 0.25 g/100 ml or 0.50 g/100 ml) and/or oil fraction (10-20 g/100 ml). At constant oil fraction, the emulsion viscosity increased as the nanocrystal concentration increased. The cellulose nanocrystal-stabilized ginger oil-Pickering emulsions exhibited shear-thinning characteristics of a pseudo-plastic fluid. Pineapple nanocellulose crystal -stabilized ginger oil-Pickering emulsions exhibited high stability with a creaming index of zero. CNC was found to be an effective Pickering stabilizer for oil-in-water emulsions in various food applications.

Large-Scale Preparation of Carboxylated Cellulose Nanocrystals and Their Application for Stabilizing Pickering Emulsions

Cellulose nanocrystals (CNCs) with varied unique properties have been widely used in emulsions, nanocomposites, and membranes. However, conventional CNCs for industrial use were usually prepared through acid hydrolysis or heat-controlled methods with sulfuric acid. This most commonly used acid method generally suffers from low yields, poor thermal stability, and potential environmental pollution. Herein, we developed a high-efficiency and large-scale preparation strategy to produce carboxylated cellulose nanocrystals (Car-CNCs) via carboxymethylation-enhanced ammonium persulfate (APS) oxidation. After carboxymethylation, the wood fibers could form unique "balloon-like" structures with abundant exposed hydroxy groups, which facilitated exfoliating fibril bundles into individual nanocrystals during the APS oxidation process. The production process under controlled temperature, time period, and APS concentrations was optimized and the resultant Car-CNCs exhibited a typical structure with narrow diameter distributions. In particular, the final Car-CNCs exhibited excellent thermal stability (≈346.6 °C) and reached a maximum yield of 60.6%, superior to that of sulfated cellulose nanocrystals (Sul-CNCs) prepared by conventional acid hydrolysis. More importantly, compared to the common APS oxidation, our two-step collaborative process shortened the oxidation time from more than 16 h to only 30 min. Therefore, our high-efficiency method may pave the way for the up-scaled production of carboxylated nanocrystals. More importantly, Car-CNCs show potential for stabilizing Pickering emulsions that can withstand changeable environments, including heating, storage, and centrifugation, which is better than the conventional Sul-CNC-based emulsions.

A Review of Pickering Emulsions: Perspectives and Applications

Pickering emulsions are systems composed of two immiscible fluids stabilized by organic or inorganic solid particles. These solid particles of certain dimensions (micro- or nano-particles), and desired wettability, have been shown to be an alternative to conventional emulsifiers. The use of biodegradable and biocompatible stabilizers of natural origin, such as clay minerals, presents a promising future for the development of Pickering emulsions and, with this, they deliver some advantages, especially in the area of biomedicine. In this review, the effects and characteristics of microparticles in the preparation and properties of Pickering emulsions are presented. The objective of this review is to provide a theoretical basis for a broader type of emulsion, in addition to reviewing the main aspects related to the mechanisms and applications to promote its stability. Through this review, we highlight the use of this type of emulsion and its excellent properties as permeability promoters of solid particles, providing ideal results for local drug delivery and use in Pickering emulsions.

Ultrasonic cavitation: An effective cleaner and greener intensification technology in the extraction and surface modification of nanocellulose

With rising consumer demand for natural products, a greener and cleaner technology, i.e., ultrasound-assisted extraction, has received immense attention given its effective and rapid isolation for nanocellulose compared to conventional methods. Nevertheless, the application of ultrasound on a commercial scale is limited due to the challenges associated with process optimization, high energy requirement, difficulty in equipment design and process scale-up, safety and regulatory issues. This review aims to narrow the research gap by placing the current research activities into perspectives and highlighting the diversified applications, significant roles, and potentials of ultrasound to ease future developments. In recent years, enhancements have been reported with ultrasound assistance, including a reduction in extraction duration, minimization of the reliance on harmful chemicals, and, most importantly, improved yield and properties of nanocellulose. An extensive review of the strengths and weaknesses of ultrasound-assisted treatments has also been considered. Essentially, the cavitation phenomena enhance the extraction efficiency through an increased mass transfer rate between the substrate and solvent due to the implosion of microbubbles. Optimization of process parameters such as ultrasonic intensity, duration, and frequency have indicated their significance for improved efficiency.

Crystallization of lipids and lipid emulsions treated by power ultrasound: A review

The actual food system with fat is always complex and fat crystal and fat crystal networks have important effects on the physical properties of food. Recently, power ultrasound (PU) had been widely recognized as an auxiliary technology of fat crystallization to modify food properties. This review expounded on the mechanism of ultrasonic crystallization, and summarized effects of various factors in the process of ultrasonic treatment on fat crystallization. Based on the above, combined with the application of ultrasound in emulsions, the ultrasonic fat crystallization effect in the emulsion system was judged and described. Research results indicated that PU could shorten the induction time of crystallization, accelerate the formation of crystal nuclei, and change the polymorphism of fat crystals. The product treated by PU formed smaller and more uniform crystals to produce a more viscoelastic fat crystal network. In emulsion systems, ultrasonic treatments showed the same effect, but the effect of ultrasonic crystallization on the emulsion stability was different due to fat crystals in different emulsion systems. Meanwhile, the importance of ultrasonic crystallization in lipid emulsions was emphasized, thus ultrasonic crystallization had great potential in emulsion systems.

Lipid-based nanoparticulate delivery systems for HER2-positive breast cancer immunotherapy

Lipid-based nanoparticulate delivery platforms such as liposomes help overcome cell and tissue barriers and allow prolonged therapeutic plasma drug concentrations, simultaneous targeting of tumor tissue, and increased bioavailability of numerous drugs used for treatment of cancer. The human epidermal growth factor receptor, HER2, is an important player in the pathogenesis of breast cancer and is considered a potential cancer biomarker for the design of immunotherapeutics. HER2-positive breast cancer is found in up to 30% of breast cancer patients. Currently, a variety of lipid nanoparticulate systems are being evaluated in preclinical settings and in clinical trials for targeting HER2-positive breast cancer. Advances in functionalized anti-HER2 lipid nanoparticulates have demonstrated promise and may lead to the development of new nano-immunotherapy protocols against HER2 positive breast cancer. Here we present a review of the most up-to-date literature, including our own research, on the use of lipid nanoparticulate carriers in immunotherapy of HER2-positive breast cancer.

Cellulose nanocrystals from ultrasound process stabilizing O/W Pickering emulsion

Cellulose nanocrystals (CNC) are bio-based solid particles arisen as promising stabilizers for Pickering emulsions in food, pharmaceutical and cosmetics industries. This study aimed to understand the stabilization mechanism of oil-in-water emulsion using CNC as stabilizing particles. CNC were obtained from cellulose microcrystalline after acid hydrolysis, dialysis, ultrasound treatment and vacuum filtration. Atomic force microscopy (AFM) showed needle-shaped CNC. The CNC presented good stability against agglomeration due to the high electrostatic repulsion between particles, making them feasible to be used in O/W emulsions. O/W emulsions were stabilized by CNC and prepared using rotor-stator and ultrasound as mechanical processes. Emulsions stabilized by CNC were opaque, homogeneous and kinetically stable during few days. Small droplets generated during the ultrasound process, could be covered by cellulose nanoparticles that acted as an effective mechanical barrier against droplets coalescence in a Pickering mechanism. The mechanism of droplets stabilization was associated with electrostatic and steric repulsion between droplets. Emulsions were evaluated varying the proportion between flaxseed oil and cellulose nanocrystals (CNC). Emulsions with a lower proportion of CNC showed better kinetic stability compared to emulsions with higher CNC proportion. After 7 days of storage, the viscosity of emulsions with a higher proportion of CNC particles decreased, which was associated to the emulsion destabilization. Our results improved the understanding of the relationship between the proportions of oil and particles for emulsion properties by evaluating the potential application of CNC as a food emulsifier.