Food Emulsion Gels from Plant-Based Ingredients: Formulation, Processing, and Potential Applications

Investigating the effects of freezing temperature and oil content on the physiochemical characteristics and stability of oil-in-water emulsions under isochoric freezing conditions

Oil-in-water emulsions are inherently unstable systems and sensitive to environmental factors such as temperature changes. This study evaluated the effects of isochoric freezing (IF) on the stability and physicochemical properties of emulsions containing 10% and 20% oil, comparing IF at -5 °C/59 MPa and -20 °C/170 MPa to conventional freezing (CF) at the same temperatures under atmospheric pressure (0.1 MPa). Emulsions were kept in IF chamber and conventional freezer at -5 °C and -20 °C for 3 days. This study analyzed microbial count, microstructure, globule size, zeta potential, viscosity, color, and stability of emulsion samples after 3 days of CF/IF. Our findings indicate that after subjecting the emulsions to IF (-20 °C/170 MPa), the counts of total aerobic microorganisms, yeast, and mold were below the detection limit. However, CF did not lead to a significant reduction in the microbial count in the emulsions. The globule size of CF 10% and 20% emulsions increased, with slower freezing rates leading to more significant increases in globule size. In contrast, we observed no significant change and a slight increase in the globule size of IF 10% and 20% emulsions, respectively. The viscosity of CF emulsions was significantly higher than that of control and IF emulsions. CF samples at -5 °C exhibited the yellowest color among samples. Our results indicate that CF emulsions were not stable to the freeze-thaw process, evidenced by a significant increase in mean globule diameter, degree of flocculation, coalescence, apparent viscosity, and yellowness. Overall, these findings suggest that IF (-20 °C/170 MPa) could effectively improve the physical stability and microbiological aspects of oil-in-water emulsions.

The impact of fish oil oxidation on interfacial properties and system stability of cod protein

In aquatic food multiphase interface systems, proteins and lipids coexist concurrently. Among them, lipids, particularly fish oil rich in polyunsaturated fatty acids, are susceptible to oxidation, resulting in oxidized products exhibiting similar interfacial activity as amphiphilic proteins. However, the interaction between oxidized fish oil products and proteins within the interface system remains unclear. As a result, this study is focused on investigating the effects of varying levels of oxidation in fish oil on the interfacial behavior of cod protein (CP), as well as on the stability, microstructure, and rheological properties of CP-fish oil emulsions. The findings revealed a significant decrease in interfacial tension (lower than 5 mN/m) at the oil-water interface after only 24 h of fish oil oxidation. Moreover, fish oil oxidation negatively influenced the behavior of cod protein at the interface, primarily manifested in the inhibition of infiltration, and rearrangement processes. Additionally, the oxidation of fish oil was found to significantly affect the centrifugal stability of the emulsion, resulting in a decrease in particle size, an increase in the absolute value of zeta potential, and improved rheological stability. The exploration of the interaction mechanism between fish oil oxidation and interface protein can offer scientific guidance for addressing the issue of uncontrollable product quality caused by fish oil oxidation in aquatic food process.

Advances in Cellulose-Based Hydrogels: Current Trends and Challenges

This paper provides a solid foundation for understanding the synthesis, properties, and applications of cellulose-based gels. It effectively showcases the potential of these gels in diverse applications, particularly in biomedicine, and highlights key synthesis methods and properties. However, to push the field forward, future research should address the gaps in understanding the environmental impact, mechanical stability, and scalability of cellulose-based gels, while also considering how to overcome barriers to their industrial use. This will ultimately allow for the realization of cellulose-based gels in large-scale, sustainable applications.

Effects of High Pressure on In Vitro Bioavailability of Curcumin Loaded in Whey Protein Isolate/Carrageenan Composite Emulsion Gel: In Vitro Digestion Coupled with Cell Culture Model

The oral bioavailability of curcumin is inherently low, which significantly limits its application in food systems. The objective of this study was to evaluate the impact of high-pressure processing on the stability and bioaccessibility of curcumin within an emulsion gel during simulated gastrointestinal transit and to assess its cellular uptake. Our findings suggest that increasing pressure levels and high κ-carrageenan concentrations can enhance the stability of the curcumin delivery system. Elevated κ-CG concentrations were found to retard the action of proteases on dissociating protein molecules from the gel network. The emulsion gel effectively slowed the release of free fatty acids and reduced the curcumin release rate during the gastric phase. Scanning electron microscopy images revealed that higher pressures induced the formation of a more uniform and dense network structure in the gel. While the gel network structures were well-preserved after gastric digestion, they were disrupted into smaller particles following intestinal digestion, with particle size increasing with higher applied pressures. Cytotoxicity assays indicated that the digesta from the intestinal phase was highly toxic to Caco-2 cells. Among the tested samples, the emulsion gel prepared with 1.0% κ-CG at 600 MPa demonstrated the highest curcumin bioavailability, reaching 63.82 ± 7.10%. These findings underscore the potential of HPP-induced emulsion gels as a viable delivery system for enhancing curcumin bioaccessibility and cellular uptake.

Recent progress in plant-based proteins: From extraction and modification methods to applications in the food industry

Plant proteins can meet consumers' demand for healthy and sustainable alternatives to animal proteins. It has been reported to possess numerous health benefits and is widely used in the food industry. However, conventional extraction methods are time-consuming, energy-intensive, as well as environmentally unfriendly. Plant proteins are also limited in application due to off-flavors, allergies, and anti-nutritional factors. Therefore, this paper discusses the challenges and limitations of conventional extraction processes. The current advances in green extraction technologies are also summarized. In addition, methods to improve the nutritional value, bioactivity, functional and organoleptic properties of plant proteins, and strategies to reduce their allergenicity are mentioned. Finally, examples of applications of plant proteins in the food industry are presented. This review aims to stimulate thinking and generate new ideas for future research. It will also provide new ideas and broad perspectives for the application of plant proteins in the food industry.

Urchin-like WO3 Particles Form Honeycomb-like Structured PLA/WO3 Nanocomposites with Enhanced Crystallinity, Thermal Stability, Rheological, and UV-Blocking and Antifungal Activity

The development of poly(lactic acid) (PLA) nanocomposites incorporating urchin-like WO3 particles through a cost-effective solution-casting method has led to significant enhancements in structural, thermal, optical, and rheological properties. The incorporation of these WO3 particles up to 7 wt% resulted in the formation of an irregular honeycomb-like morphology with broad pore sizes ranging from 14.1 to 24.7 µm, as confirmed by SEM and EDX analysis. The urchin-like WO3 particles acted as effective nucleating agents, increasing the crystallinity of PLA from 40% to 50% and achieving an impressive overall crystallinity rate of 97%. Differential scanning calorimetry (DSC) revealed an 11 K reduction in the crystalline phase transition temperature while maintaining stable melting (Tm) and glass transition (Tg) temperatures. Thermal analysis indicated a significant decrease in the onset of degradation and maximum thermal stability (Tmax), with a reduction of 21 K due to the incorporation of the WO3 particles. Optical measurements showed enhancement of UV-blocking properties from 9% to 55% with the WO3 particle loading. Rheological tests demonstrated substantial improvements in viscoelastic properties, including a remarkable 30-fold increase in storage modulus, suggesting enhanced gel formation. Although the nanocomposites showed minimal antibacterial activity against Escherichia coli and Staphylococcus aureus, they exhibited significant antifungal activity against Candida albicans. These results underscore the potential of the PLA/WO3 nanocomposites for advanced material applications, particularly where enhanced mechanical, thermal, optical, and antifungal performance is required.

Binary Pea Protein-Psyllium Hydrogel: Insights into the Influence of pH and Ionic Strength on the Physical Stability and Mechanical Characteristics

Food hydrogels, used as delivery systems for bioactive compounds, can be formulated with various food-grade biopolymers. Their industrial utility is largely determined by their physicochemical properties. However, comprehensive data on the properties of pea protein-psyllium binary hydrogels under different pH and ionic strength conditions are limited. The aim of this research was to evaluate the impact of pH (adjusted to 7, 4.5, and 3) and ionic strength (modified by NaCl addition to 0.15 and 0.3 M) on the physical stability, color, texture, microrheological, and viscoelastic properties of these hydrogels. Color differences were most noticeable at lower pH levels. Inducing hydrogels at pH 7 (with or without NaCl) and pH 4.5 and 3 (without NaCl) resulted in complete gel structures with low stability, low elastic and storage moduli, and low complex viscosity, making them easily spreadable. Lower pH inductions (4.5 and 3) in the absence of NaCl resulted in hydrogels with shorter linear viscoelastic regions. Hydrogels induced at pH 4.5 and 3 with NaCl had high structural stability, high G' and G" moduli, complex viscosity, and high spreadability. Among the tested induction conditions, pH 3 with 0.3 M NaCl allowed for obtaining a hydrogel with the highest elastic and storage moduli values. Adjusting pH and ionic strength during hydrogel induction allows for modifying and tailoring their properties for specific industrial applications.

Heat-Induced Gelation of Chickpea and Faba Bean Flour Ingredients

This study aimed to investigate the gelling behavior of faba bean (FB) and chickpea (CP) flour between 10 and 20% (w/w) concentration at pH 3.0, 5.0, and 7.0. Both sources formed at pH 3.0 and 5.0 self-standing gels with 12% (w/w) of flour, while 16% (w/w) of flour was required to obtain a gel at pH 7.0. During gelling between 40 and 70 °C, a sharp increase of the elastic modulus G' was observed in both flours, mainly due to water absorption and swelling of the starch, one of the major constituents in the ingredients. Increasing the temperature at 95 °C, G' increased due to the denaturation of globulins and therefore the exposure of their internal part, which allowed more hydrophobic interactions and the formation of the gel. After cooling, both FB and CP gels displayed a solid-like behavior (tan δ ranging between 0.11 and 0.18) with G' values at pH 3.0 and 5.0 significantly (p < 0.05) higher than those at pH 7.0, due to the lower electrostatic repulsions at pHs far from the isoelectric point. The rheological properties were supported by the water binding capacity values, confirming the better gels' strength described by rheological analysis. These results will enhance our understanding of the role of legume flours in formulating innovative and sustainable food products as alternatives to animal ones.

Plant-Based Emulsions as Dairy Cream Alternatives: Comparison of Viscoelastic Properties and Colloidal Stability of Various Model Products

In the context of growing interest in plant-based food products for their potential health benefits and sustainability, this study investigates the effect of mono- and diglycerides of fatty acids application on physico-chemical properties of various plant-based cream products, compared to lecithin application in rice cream. Rheological and textural parameters, colour profile, and colloidal stability were analysed. The application of mono- and diglycerides modified the creams' viscoelastic behaviour, showing a decrease in viscoelasticity across the samples; although in oat-coconut cream resulted in a higher viscoelasticity, indicating the formation of a gel-like structure. Rice cream with lecithin emulsifier showed lower viscoelastic properties characterised by higher phase angle (tan δ). All samples behaved as pseudoplastic materials (with a flow behaviour index n < 1). For coconut and almond creams, the consistency coefficient increased and flow behaviour index decreased after emulsifier application. Interestingly, the emulsifier addition did not significantly affect the cream's colour profile, characterised by yellow hue angle (h*) as a dominant spectral component. The colloidal stability, indicated by a stability index (SI), was determined as well.

Protein-stabilized Pickering emulsion interacting with inulin, xanthan gum and chitosan: Rheological behavior and 3D printing

Physical stability and lipid digestion of protein-stabilized Pickering emulsions interacting with polysaccharides have been emphasized in our previous investigation. However, the polysaccharide coating and micelle protection of protein-based stable Pickering emulsion and its three-dimensional (3D) printing properties have not been thoroughly studied. The rheological properties and 3D printing properties of gelatin-catechin nanoparticles (GCNPs) stabilized Pickering emulsion were studied by using different charged polysaccharides, such as inulin (neutral), Xanthan gum (XG, anion), and chitosan (cation) as stable materials. The microstructure analysis of polysaccharide-stabilized Pickering emulsion (PSPE) showed that the order of pore wall thickness was GC-Chitosan > GC-XG > GC-Inulin. The network structure of GC-Chitosan was thickened, allowing the 3D printed product to have a good surface texture and adequate support. Rheological analysis showed that PSPEs in extrusion (shear thinning), self-support (rigid structure), and recovery (the outstanding thixotropy) of the three stages exhibited good potential of 3D printing. 3D printing results also showed that GC-Chitosan had the best printing performance. Therefore, polysaccharide-stabilized Pickering emulsions can provide a basis for the development of 3D printed food products.

A comparative study of the impacts of preparation techniques on the rheological and textural characteristics of emulsion gels (emulgels)

A subtype of soft solid-like substances are emulsion gels (emulgels; EGs). These composite material's structures either consist of a network of aggregated emulsion droplets or a polymeric gel matrix that contains emulsion droplets. The product's rheological signature can be used to determine how effective it is for a specific application. The interactions between these structured system's separate components and production process, however, have a substantial impact on their rheological imprint. Therefore, rational comprehension of interdependent elements, their structural configurations, and the resulting characteristics of a system are essential for accelerating our progress techniques as well as for fine-tuning the technological and functional characteristics of the finished product. This article presents a comprehensive overview of the mechanisms and procedures of producing EGs (i.e., cold-set and heat-set) in order to determine the ensuing rheological features for various commercial applications, such as food systems. It also describes the influence of these methods on the rheological and textural characteristics of the EGs. Diverse preparation methods are the cause of the rheological-property correlations between different EGs. In many ways, EGs can be produced using various matrix polymers, processing techniques, and purposes. This may lead to various EG matrix structures and interactions between them, which in turn may affect the composition of EGs and ultimately their textural and rheological characteristics.