Fat crystallisation at oil-water interfaces

Modulation of coconut oil crystallization by DATEM and glycerol monostearate for the creation of nanostructured lipid carriers

The feasibility of developing nanostructured lipid carriers (NLCs) based on coconut oil (CO) was analyzed by studying the crystallization behavior of bulk and emulsified CO in the presence of diacetyl tartaric acid ester of monoglycerides (DATEM) and glycerol monostearate (GM). Supercooling was almost halved compared to pure CO, and crystallization began at higher temperatures due to the seed effect of the emulsifiers. A significant difference in the crystallization enthalpy (ΔH) of CO was observed. Consequently, the solid fat content decreased to only 63-66 % when CO was emulsified. Both pure and emulsified CO crystallized in the β'-2 polymorph. The Avrami model showed reduced crystal dimensionality in CO-emulsifier blends and emulsions. NLCs derived from CO emulsions formulated with GM as emulsifier were most suitable due to the absence of flocculation, reduced CO crystallization, and melting above 37 °C.

Plant-based whipping cream: A promising sustainable alternative to dairy products

Future food is dedicated to transforming the traditional production model of the food industry, making people and the planet healthier, and addressing the challenges facing humanity. The development of plant-based foods is one of the core contents of future food and an important way to achieve green and low-carbon development of the food industry. A prevailing food trend in the dairy industry is the demand to develop various plant-based alternatives to dairy products. Plant-based whipping cream is a complex emulsion-foam system that can be transformed from an oil-in-water emulsion structure to a triphasic (solid-liquid-gas) foam structure by whipping, which should achieve a subtle balance between emulsion stability, whipping destabilization, and foam re-stabilization. This review aims to understand the science and technology underlying the development of plant-based whipping cream. The initial focus is on the fundamental principle of stabilization and destabilization of plant-based whipping cream, as the development of successful products depends on understanding their physicochemical basis. Three main processing technologies for the manufacture of plant-based whipping cream are then introduced: homogenization, sterilization, and tempering. Besides that, the role of the basic ingredients in plant-based whipping cream is highlighted, including vegetable fats, plant proteins, low-molecular-weight emulsifiers, and thickeners. In order to quantify and compare the quality attributes of different plant-based whipping cream products under standardized conditions, we provide an overview of characterization methods to evaluate emulsion stability, whipping destabilization, and foam re-stabilization of plant-based whipping cream. Subsequently, the legislations and regulations related to plant-based whipping cream products are introduced to cater to their market development. Finally, the current challenges faced by plant-based whipping cream are highlighted. This review aims to provide a guidance for researchers and manufacturers in related industries.

Nucleation and Supercooling Mitigation in Fatty Alcohol Phase Change Material Emulsions for Heat Transport and Storage

Organic phase change slurries (PCS) exhibit significant supercooling in small particles, which diminishes their advantages over sensible heat storage systems by reducing energy efficiency and reliability. While the mechanisms of supercooling in alkanes have been extensively studied, investigations of emulsions containing fatty alcohols are limited. This study examines the impact of nucleating agents on reducing supercooling in oil-in-water (O/W) emulsions of 1-docosanol, a fatty alcohol used as a phase change material (PCM). Emulsions with platykurtic particle size distributions were produced using rotor-stator emulsification. Various material combinations were explored to identify nucleation promoters compatible with 1-docosanol. Thermal analysis revealed that long-chain polymers effectively mitigate supercooling, particularly during rotator phase transitions, as confirmed by crystal structure analysis. On average, supercooling was reduced by 9 K; however, seed deactivation observed over multiple thermal cycles led to a gradual return of supercooling. Similar to alkanes, particle size influences the nucleation rate, surfactants affect the availability of heterogeneous nucleation sites, and nucleating agents can decrease the nucleation barrier. The findings indicate that high structural similarity between emulsion components is beneficial for minimizing supercooling in PCS, enhancing their potential for thermal energy storage applications.

Templating effect of monoglycerides in controlling the spatial distribution of solid fat crystals within double emulsions

The spatial distribution of fat crystals significantly impacts the stability and digestion properties of emulsions. This study investigated the templating effect of monoglycerides in controlling the spatial distribution of solid fat crystallization within double emulsions. Double emulsions were formulated with glyceryl monostearate (GMS), glyceryl monolaurate (GML), glyceryl monooleate (GMO), beeswax (BW), glyceryl distearate (GDS), and glyceryl tristearate (GTS) in the oil phase. Monoglycerides influenced the spatial distribution pattern of BW crystals, while minimally affecting GDS and GTS. Cooling at 4 °C increased interfacial crystallization without altering distribution patterns. Monoglycerides raised the onset and peak crystallization temperatures and enthalpy in BW emulsions, with GMS showing the most significant effects. Adding GMS slowed nucleation rates and extended induction times, promoting interface crystallization. The templating effect also reduced crystal lamellar thickness, facilitating the transition from β-crystalline to β' crystalline in BW. These findings provide insights into selecting crystallizing emulsifiers and enhancing double emulsion stability.

Self-Assembly at Oil-Water Interfaces Driven by Solubility Differences and Polar-Hydrophobic Interactions: An Insight into a Highly Mechanical Performance Gel with Gradients

Interfacial self-assembly offers a promising route to fabricate functional materials, yet achieving robust mechanical performance remains challenging. Here, the self-assembly of nonionic surfactant polyoxyethylene monoalkyl ether (AEO-9) at oil-water interfaces was systematically investigated to form a high-strength interfacial gel. During the self-assembly process, the mechanical strength of the interfacial gel progressively increased, reaching a maximum equilibrium value of 4200 Pa after 24 h. Furthermore, significant gradients in the composition, microstructure, and micromechanical properties of the interfacial gel along the sample height were revealed by fluorescence microscopy, small-angle X-ray scattering (SAXS), and atomic force microscopy (AFM). This unique interfacial self-assembly behavior was further studied via dynamic light scattering and molecular simulations. The solubility differences and polar-hydrophobic interactions are the key factors. Directional migration of AEO-9 from the oil phase (low solubility) to the aqueous phase (high solubility), driven by solubility differences, was found to establish a transient interfacial concentration gradient. This gradient facilitated interfacial enrichment of AEO-9, which was subsequently organized into gradient lamellar liquid crystals (LC) through compositional heterogeneity and polar-hydrophobic interactions. The gradient variations in micromechanical properties were correlated with the gradient structural packing. Moreover, the effects of AEO-9 concentration, brine, temperature, and oil type on the gel's mechanical properties were examined, highlighting their roles in modulating the polar-hydrophobic balance. This study reveals the dual control of solubility-driven migration and interfacial interactions on gradient formation, establishing a framework for the design of high-performance interfacial materials.

Fabrication and characterization of non-diary whipped creams: Influence of oleogel

Non-dairy whipped creams (NDWC) are a typical food emulsion system and are gaining popularity among consumers. Oleogels as reasonable alternatives to trans and saturated fats in foods show great potential application in NDWC. Effects of different proportions of oleogel (30 %-70 %) as base oil on the crystallization behavior, appearance, interface and rheological properties of NDWC were evaluated. The base oil made of oleogel and sunflower oil can crystallize at 0-10 °C, showing needle-liked β-crystal crystal structure. A higher oleogel proportion increased solid fat index, fat crystals and fractal dimension. The fat coalescence rate in NDWC gradually increased from 205.88 % to 465.96 % as oleogel ratio increased from 30 % to 70 %, which was beneficial to the network structure formation of NDWC. The increase of oleogel ratio effectively reduced interfacial tension and increased the elastic modulus as well as promoted partial fat coalescence, thus facilitated the formation and stabilization of the NDWC system.

Fabrication of Rubus chingii Hu ellagitannins-loaded W/O and O/W emulsion gels: Structure, stability, in vitro digestion and in vivo metabolism

Tannin is the main naturally occurring phytochemicals in Rubus chingii Hu with poor digestive stability and low bioavailability. In this study, oil-in-water (O/W) and water-in-oil (W/O) emulsion gels encapsulating Rubus chingii Hu ellagitannins (RCHT) were fabricated and their structure, rheology, stability, in vitro digestion and in vivo metabolism were characterized. The W/O emulsion gel showed smaller particle size, better pH stability, thermal stability, centrifugal stability and storage stability. Regarding rheology, two emulsion gels exhibited characteristics of non-Newtonian fluids. The encapsulation efficiency of W/O emulsion gel was higher, reaching 95.46 %. The lower release rate and higher bioaccessibility of RCHT were also observed in the W/O emulsion gel. In vitro fermentation results indicated that W/O emulsion gel could promote the growth of intestinal beneficial bacteria and inhibit the growth of harmful bacteria. Metabolic kinetics in rats showed that the embedding of W/O emulsion gel greatly promoted the absorption and transformation of ellagitannins to urolithins in vivo. Thus, the W/O emulsion gel was quite suitable for the delivery of RCHT.

Ultrasonic combined pH shifting strategy for improving the stability of emulsion stabilized by yeast proteins: Focused on solubility, protein structure, interface properties

In this study, the improvement mechanism of yeast proteins (YPs) with the ultrasonic and pH shifting treatment on the emulsion stability was investigated through the solubility, protein structure and interface behavior of YPs. Compared with only pH shifting or ultrasound treatment, the solubility of YPs with the combined treatment of ultrasonic and pH shifting was increased significantly. The soluble protein content of pH-U400 reached 85.51 %. The results of YPs structure demonstrated that the β-sheet, α-helix and disulfide bonds contents of YPs with the combined treatment first declined and subsequently increased with increasing ultrasonic power, under alkaline conditions. The fluorescence intensity and surface hydrophobicity first increased and then declined. The more flexible protein structure endowed pH-U400 with lower interfacial tension, higher interfacial diffusion, penetration and reorganization rate, and interfacial protein concentration. The pH-U400 showed the best emulsifying properties (emulsifying activity index was 27.05 m2/g, emulsifying stability index was 31.27 min) and could prepare smaller and more uniform emulsion droplet. The results of multiple light scattering demonstrated that emulsion stabilized by pH-U400 showed the best stability. These results revealed the stability mechanism of emulsions stabilized by YPs and provided guidance for further development of practical YPs products in the food industry.

Plant-based protein emulsions with soy protein isolate and gluten improve freeze-thaw stability and shelf life of pork meatballs

This study investigated the effects of oil-in-water emulsions used as fat substitutes on the physicochemical properties of meatballs during frozen storage. Different formulations of fat replacers were prepared, including pork fat as the control (C), oil and water (OW), oil-in-water emulsion (E), emulsion with soy protein isolate (SE), emulsion with gluten (GE), and emulsion with soy protein isolate and gluten (SG). These fat substitutes were applied to a meatball paste. The samples were stored at -18 °C for 30 and 60 days, and their physicochemical properties were analyzed after thawing at 4 °C for 12 h. The SE formulation had the highest values for both water content and liquid holding capacity during frozen storage (P < 0.05). SE, GE, and SG showed significantly higher hardness, cohesiveness, springiness, gumminess, and chewiness than those of E during storage (P < 0.05). The vegetable protein addition treatments maintained a compact structure throughout storage. SE, GE, and SG prevented lipid and protein oxidation during frozen storage. These results demonstrated that SE, GE, and SG offer significant advantages in improving the freeze-thaw stability, liquid holding capacity, and oxidation stability of pork meatballs during long-term frozen storage. Therefore, our study suggest that plant-based protein emulsions can effectively replace animal fats while maintaining product quality, offering valuable implications for the meat processing industry.

Control of emulsion crystal growth in low-temperature environments

Currently, various types of emulsions can be applied to a wide range of systems. Emulsions are thermodynamically unstable systems, and their crystallization can be affected by a variety of factors. The nucleation and growth processes of emulsion crystal networks are determined on the basis of reported theoretical and experimental methods. The issues addressed include changes in the apparent crystal morphology of samples, changes in thermal properties with respect to temperature, changes in boundary conditions, and changes in the various applications of emulsions as feedstocks or in processing and storage methods. Changes in a variety of common emulsions during constant-temperature storage and unavoidable temperature fluctuations (e.g., multiple freeze-thaw cycles) are considered. Different methods for controlling the crystalline stability of these colloidal systems are also discussed. This review outlines the crystallization mechanism of emulsions during their food processing and storage.

Pickering Emulsion Stabilized by Different Concentrations of Whey Protein-Cress Seed Gum Nanoparticles

Nanoparticles based on food-grade materials are promising materials to develop Pickering emulsions for food applications. Initially, this study focuses on the development of nanoparticles through the utilization of a soluble complex of whey protein concentrate (WPC) and cress seed gum (CSG), which were modified by calcium chloride (CaCl2) as a cross-linker. The response surface methodology was used to investigate the impact of different concentrations of WPC (1-4% w/v), CSG (0-1% w/v), and CaCl2 (1-3 mM) on particle size, polydispersity index (PDI), and Zeta potential. The optimum conditions for the production of CSG-WPC nanoparticles (WPC-CSG NPs) were 0.31% (w/v) CSG, 1.75% (w/v) WPC, and 1.69 mM CaCl2, resulting in nanoparticles with average size of 236 nm and Zeta potential of -22 mV. Subsequently, oil-in-water (O/W) Pickering emulsions were produced with different concentrations of WPC-CSG NPs in optimum conditions. The contact angles of the WPC-CSG NPs were 41.44° and 61.13° at concentrations of 0.5% and 1%, respectively, showing that NPs are suitable for stabilizing O/W Pickering emulsions. Pickering emulsion viscosity rose from 80 to 500 mPa when nanoparticle concentration increased from 0.5% to 1%. Results also showed that WPC-CSG NPs enable stable O/W Pickering emulsions during storage and thermal treatment, confirming that protein-polysaccharide NPs can provide a sufficient steric hindrance.

Emulsions stabilized by pea protein-rich ingredients as an alternative to dairy proteins for food sustainability: Unveiling the key role of pea endogenous lipids in the surface-induced crystallization of milk fat

In the current context of food transition, the growing demand of consumers for sustainable plant-based protein sources has stimulated interest of food scientists in plant protein ingredients as alternatives to dairy protein ingredients. In this study, we hypothesized that the crystallization properties of dairy emulsions could be affected by the chemical complexity of commercially available pea protein-rich ingredients that contain proteins but also endogenous lipids. Dairy emulsions (30 %wt milk fat) stabilized either by a pea protein isolate or dairy proteins were prepared, their microstructure and interfacial composition were characterized. The crystallization and melting properties of milk fat in anhydrous state and in the emulsions were examined by the combination of differential scanning calorimetry (DSC) and synchrotron-radiation X-ray diffraction as a function of temperature (SR-XRDT). The results revealed differences in the milk fat crystallization properties in emulsion as a function of the ingredient used and highlighted a specific role played by pea endogenous lipids. The pea protein-rich ingredient contained 12.1 %wt endogenous lipids including 56.2 %wt polar lipids, 40.7 %wt triacylglycerols (TAGs) and 3.1 %wt plant sterols. The partitioning of pea endogenous lipids occurred upon emulsion formation as a function of their polarity: liquid unsaturated fatty acid rich pea TAGs mixed with milk TAGs in the core of the lipid droplets while pea polar lipids migrated at the TAGs/water interface together with pea proteins. Pea polar lipids were composed of saturated high melting temperature (Tm) and unsaturated low Tm molecular species. High Tm pea polar lipids exhibited a phase transition on cooling (from Lα/expansed to Lβ/condensed) and acted as interfacial templates for surface heterogeneous nucleation and crystal growth of high crystallization temperature milk TAGs. The key interfacial and functional roles played by pea endogenous lipids present in the protein isolate were demonstrated. This study highlights the importance to examine the chemical composition and the properties of plant-based ingredients that are increasingly used for sustainable food formulations.

In situ single-droplet analysis of emulsified fat using confocal Raman microscopy: insights into crystal network formation within spatial resolution

Fat crystallization is one of the predominant factors influencing the structure and properties of fat-containing emulsions. In the present study, the role of emulsifiers on fat crystallization dynamics within droplet multiphase systems was evaluated via single-droplet analysis, taking advantage of the non-destructive properties of confocal Raman microscopy. Palm oil droplets dispersed in water were used as a model system, due to palm oil's well-known crystallization properties. Emulsion droplets of the same size were generated using two different emulsifiers (Whey Protein Isolate and Tween 60), at various concentrations. Fast and slow cooling treatments were applied to affect fat crystallisation and network formation as well as droplet morphology, and crystallization dynamics. Raman imaging analysis demonstrated that the chemical structure and concentration of the emulsifier significantly influenced both crystal nucleation within the droplets, as well as the spatial distribution and morphology of the fat crystal network. Additionally, analysis of the spectra of the crystallized phase provided essential information regarding the impact of the emulsifiers on the microstructure, degree of structural order, and structural arrangements of the fat crystal networks. Furthermore, by performing single droplet analysis during cooling it was possible to observe shape distortions in Tween 60 stabilized droplets, as a consequence of the formation of a three-dimensional network of fat crystals that strongly interacted with the interface. On the other hand, the droplets retained their shape when whey proteins were absorbed at the interface. Confocal Raman microscopy, in combination with polarized light microscopy, is, therefore, a well-suited tool for in situ, single-droplet analysis of emulsified oil systems, providing essential information about emulsified fat crystallization dynamics, contributing to better understanding and designing products with enhanced structure and function.

Recent advances in studying crystallisation of mono- and di-glycerides at oil-water interfaces

This review focuses on the current understanding regarding lipid crystallisation at oil-water interfaces. The main aspects of crystallisation in bulk lipids will be introduced, allowing for a more comprehensive overview of the crystallisation processes within emulsions. Additionally, the properties of an emulsion and the impact of lipid crystallisation on emulsion stability will be discussed. The effect of different emulsifiers on lipid crystallisation at oil-water interfaces will also be reviewed, however, this will be limited to their impact on the interfacial crystallisation of monoglycerides and diglycerides. The final part of the review highlights the recent methodologies used to study crystallisation at oil-water interfaces.

Self-constructed water-in-oil Pickering emulsions as a tool for increasing bioaccessibility of betulin

Self-constructed water-in-oil emulsions can be stabilized by a natural pentacyclic triterpenoid, betulin. A higher betulin concentration (3%) results in smaller emulsion droplet sizes. Microscopy, confocal laser scanning microscopy and rheology indicate that the stabilizing mechanism is attributed to betulin crystals on the emulsion interface and within the continuous phase, thereby enabling excellent freeze/thaw and thermal stability. The betulin Pickering emulsion (1%) significantly increased betulin bioaccessibility (22.4%) compared to betulin alone (0.2%) and betulin-oil physical mixture (7.9%). A higher level of betulin at 3% leads to smaller emulsion particle size, potentially resulting in a greater surface area. This, in return, promotes a higher release of free fatty acids (FFA), contributing to the release and solubilization of betulin from emulsions. Additionally, it leads to the formation of micelles, further increasing betulin bioaccessibility (29.3%). This study demonstrates Pickering emulsions solely stabilized by phytochemical betulin provides an innovative way to improve its bioaccessibility.

Polymorphic phase transitions in triglycerides and their mixtures studied by SAXS/WAXS techniques: In bulk and in emulsions

Triacylglycerols (TAGs) exhibit a monotropic polymorphism, forming three main polymorphic forms upon crystallization: α, β' and β. The distinct physicochemical properties of these polymorphs, such as melting temperature, subcell lattice structure, mass density, etc., significantly impact the appearance, texture, and long-term stability of a wide range products in the food and cosmetics industries. Additionally, TAGs are also of special interest in the field of controlled drug delivery and sustained release in pharmaceuticals, being a key material in the preparation of solid lipid nanoparticles. The present article outlines our current understanding of TAG phase behavior in both bulk and emulsified systems. While our primary focus are investigations involving monoacid TAGs and their mixtures, we also include illustrative examples with natural TAG oils, highlighting the knowledge transfer from simple to intricate systems. Special attention is given to recent discoveries via X-ray scattering techniques. The main factors influencing TAG polymorphism are discussed, revealing that a higher occurrence of structural defects in the TAG structure always accelerates the rate of the α → β polymorphic transformation. Diverse approaches can be employed based on the specific system: incorporating foreign molecules or solid particles into bulk TAGs, reducing drop size in dispersed systems, or using surfactants that remain fluid during TAG particle crystallization, ensuring the necessary molecular mobility for the polymorphic transformation. Furthermore, we showcase the role of TAG polymorphism on a recently discovered phenomenon: the creation of nanoparticles as small as 20 nm from initial coarse emulsions without any mechanical energy input. This analysis underscores how the broader understanding of the TAG polymorphism can be effectively applied to comprehend and control previously unexplored processes of notable practical importance.

Emulsion Gels Formed by Electrostatic Interaction of Gelatine and Modified Corn Starch via pH Adjustments: Potential Fat Replacers in Meat Products

The application of emulsion gels as animal fat replacers in meat products has been focused on due to their unique physicochemical properties. The electrostatic interaction between proteins and polysaccharides could influence emulsion gel stability. This study aimed to evaluate the physicochemical properties of emulsion gels using starch and gelatin as stabilizers, promoting electrostatic attraction via pH adjustment. Three systems were studied: emulsion gel A (EGA) and emulsion gel B (EGB), which have positive and negative net charges that promote electrostatic interaction, and emulsion gel C (EGC), whose charge equals the isoelectric point and does not promote electrostatic interactions. There was no significant difference in proximate analysis, syneresis and thermal stability between samples, while EGA and EGB had higher pH values than EGC. The lightness (L*) value was higher in EGA and EGB, while the yellowness (b*) value was the highest in EGC. The smaller particle size (p < 0.05) in EGA and EGB also resulted in higher gel strength, hardness and oxidative stability. Microscopic images showed that EGA and EGB had a more uniform matrix structure. X-ray diffraction demonstrated that all the emulsion gels crystallized in a β′ polymorph form. Differential scanning calorimetry (DSC) revealed a single characteristic peak was detected in both the melting and cooling curves for all the emulsion gels, which indicated that the fat exists in a single polymorphic state. All emulsion gels presented a high amount of unsaturated fatty acids and reduced saturated fat by up to 11%. Therefore, the emulsion gels (EGA and EGB) that favored the electrostatic protein-polysaccharide interactions are suitable to be used as fat replacers in meat products.

Tracing distribution and interface behavior of water droplets in W/O emulsions with fat crystals

Sucrose palmitate (P170) and sucrose laurate (L195) were used as emulsifiers to control the crystallization behavior of AMF and to stabilize W/O emulsions. In this study, the P170 promoted crystallization and led to strong fat crystal networks with smaller AMF crystals (60-80 μm) in emulsions, retaining flocculation. Water droplets were squeezed into irregular shapes between the strong network but the P170 formed an interface layer with better strength to resist the aggregation. Contrarily, the L195 inhibited crystallization and formed larger AMF spherulites (more than 100 μm) resulting in a low strength of fat crystal networks and unstable emulsions. Meanwhile, the water droplets were easily fixed on the surface of AMF crystals because of the existence of sucrose esters. Protruding crystals on the surface of larger spherulites could pierce the water-oil interface, leading to a greater coalescence and forming larger water droplets. Therefore, a weak crystal network could not prevent the sedimentation and phase separation caused by gravity.

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.

Effects of Sorbitan Monostearate and Stearyl Alcohol on the Physicochemical Parameters of Sunflower-Wax-Based Oleogels

A rising health concern with saturated fatty acids allowed researchers to look into the science of replacing these fats with unsaturated fatty acids. Oleogelation is a technique to structure edible oil using gelators. The present study looked for the effect of solid emulsifiers; namely, sorbitan monostearate (SP) and stearyl alcohol (SA), on the physicochemical parameters of oleogels. All the oleogels were formulated using 5% sunflower wax (SW) in sunflower oil (SO). The formulated oleogels displayed irregular-shaped wax crystals on their surface. The bright-field and polarized microscopy showed the fiber/needle network of wax crystals. Formulations consisting of 10 mg (0.05% w/w) of both the emulsifiers (SA10 and SP10) in 20 g of oleogels displayed the appearance of a dense wax crystal network. The SP and SA underwent co-crystallization with wax molecules, which enhanced crystal growth and increased the density and size of the wax crystals. The XRD and FTIR studies suggested the presence of a similar β’ polymorph to that of the triacylglycerols’ arrangement. The incorporation of SA and SP in wax crystal packing might have resulted in a lower crystallization rate in SA10 and SP10. Evaluation of the thermal properties of oleogels through DSC showed better gel recurrence of high melting enthalpy. These formulations also displayed a sustained release of curcumin. Despite the variations in several properties (e.g., microstructures, crystallite size, thermal properties, and nutrient release), the emulsifiers did not affect the mechanical properties of the oleogel. The meager amounts of both the emulsifiers were able to modulate the nutrient release from the oleogels without affecting their mechanical properties in comparison to the control sample.

Effects of the Distribution Site of Crystallizable Emulsifiers on the Gastrointestinal Digestion Behavior of Double Emulsions

Double emulsions (DEs) are promising delivery vehicles for the protective and programmed release of bioactive compounds. Herein, DEs with monoglycerides crystallized at the internal- or external interface or oil phase were fabricated. The results suggested that the crystallization site of monoglycerides exerts a significant role in retarding the structural degradation and lipid digestion of DEs by affecting the available contact area of lipase. At the initial stage of intestinal digestion, compared with noncrystalline DEs (82.1%, 3.7 min), the burst release of internal markers in the internal interface crystallized emulsions was decreased by 42.4% and the lag time of free fatty acid (FFA) release was delayed by 5.8 min in the external interface crystallized emulsions. The structural integrity and digestion kinetics of the external interface crystallized DEs were synchronized with the retention time of the interfacial crystals. Therefore, crystallizable emulsifiers exhibit unique and fine regulatory effects on the digestive properties of emulsions.

The effect of emulsifier type on the secondary crystallisation of monoacylglycerol and triacylglycerols in model dairy emulsions

Dairy emulsions contain an intrinsically heterogeneous lipid phase, whose components undergo crystallisation in a manner that is critical to dairy product formulation, storage, and sensory perception. Further complexity is engendered by the diverse array of interfacially-active molecules naturally present within the serum of dairy systems, and those that are added for specific formulation purposes, all of which interact at the lipid-serum interface and modify the impact of lipid crystals on dairy emulsion stability. The work described in this article addresses this complexity, with a specific focus on the impact of temperature cycling and the effect of emulsifier type on the formation and persistence of lipid crystals at lipid-solution interfaces. Profile analysis tensiometry experiments were performed using single droplets of the low melting fraction of dairy lipids, in the presence and absence of emulsifiers (Tween 80 and whey protein isolate, WPI) and during the temperature cycling, to study the formation of monoacylglycerol (MAG) crystals at the lipid-solution interface. Companion experiments on the same lipid systems, and at the same cooling and heating rates, were undertaken with synchrotron small angle X-ray scattering, to specifically analyse the effect of emulsifier type on the formation of triacylglycerol (TAG) crystals at the lipid-solution interface of a model dairy emulsion. These two complementary techniques have revealed that Tween 80 molecules delay MAG and TAG crystal formation by lowering the temperature at which the crystallisation occurs during two cooling cycles. WPI molecules delay the crystallisation of MAGs and TAGs during the first cooling cycle, while MAG crystals form without delay during the second cooling cycle at the same temperature as MAG crystals in an emulsifier free system. The crystallisation of TAGs is inhibited during the second cooling cycle. The observed differences in crystallisation behaviour at the interface upon temperature cycling can provide further insight into the impact of emulsifiers on the long-term stability of emulsion-based dairy systems during storage.

Effects of natural waxes on the interfacial behavior, structural properties and foam stabilization of aerated emulsions

Aerated emulsions have widespread applications in food industry. However, the poor stability of aerated emulsions remains a major challenge due to their inherent thermodynamic instability. Herein, a novel strategy to...

Oleogel-based emulsions: Concepts, structuring agents, and applications in food

This review discusses the application of oleogel technology in emulsified systems. In these systems of mimetic fats, water-in-oil or oil-in-water emulsions can be obtained, but, here, we cover emulsions with an oil continuous phase in detail. Depending on the percentage of water added to the oleogels, systems with different textures and rheological properties can be developed. These properties are affected by the characteristics and concentration of the added components and emulsion preparation methods. In addition, some gelators exhibit interfacial properties, resulting in more stable emulsions than those of conventional emulsions. Oleogel-based emulsion are differentiated by continuous and dispersed phases and the structuring/emulsification components. Crucially, these emulsions could be applied by the food industry for preparing, for example, meat products and margarines, as well as by the cosmetics industry. We present the different processes of emulsion elaboration, the main gelators used, the influence of the water content on the structuring of water-in-oleogel emulsions, and the structuring mechanisms (Pickering, network, and combined Pickering and network stabilization). Finally, we highlight the applications of these systems as alternatives for reducing processed food lipid content and saturated fat levels.

Influence of Emulsifiers and Dairy Ingredients on Manufacturing, Microstructure, and Physical Properties of Butter

The influence of emulsifiers and dairy solids on churning and physical attributes of butter was investigated. Commercial dairy cream was blended with each of the ingredients (0.5%, w/w) separately, aged overnight (10 °C), and churned (10 °C) into butter. The employed additives showed a distinctive impact on the macroscopic properties of butter without largely affecting the melting behavior. In fresh butter, polyglycerol polyricinoleate (PGPR) emulsifier having dominated hydrophobic moieties significantly (p < 0.05) enhanced the softness. Among dairy solids, sodium caseinate (SC) was the most effective in reducing the solid fat fraction, hardness, and elastic modulus (G'), while whey protein isolate (WPI) and whole milk powder (WMP) produced significantly harder, stiffer, and more adhesive butter texture. As per tribological analysis, PGPR, Tween 80, and SC lowered the friction-coefficient of butter, indicating an improved lubrication property of the microstructure. The extent of butter-setting during 28 days of storage (5 °C) varied among the samples, and in specific, appeared to be delayed in presence of WPI, WMP, and buttermilk solids. The findings of the study highlighted the potential of using applied emulsifiers and dairy-derived ingredients in modifying the physical functionality of butter and butter-like churned emulsions in addition to a conventional cream-ageing process.

Effect of Sucrose Esterified Fatty Acid Moieties on the Crystal Nanostructure and Physical Properties of Water-in-oil Palm-based Fat Blends

The effects of sucrose ester of fatty acid (SEF) on the nanostructure and the physical properties of water-in-oil (W/O)-type emulsified semisolid fats were investigated. Model emulsions including palm-based semisolid fats and fully hydrogenated rapeseed oils with 0.5% SEF or fractionated lecithin, were prepared by rapidly cooling crystallization using 0.5% monoacylglycerol as an emulsifier. The SEFs used in this study were functionalized with various fatty acids, namely, lauric, palmitic, stearic, oleic, and erucic acids. Cryogenic transmission electron microscopy (cryo-TEM) was used to observe the sizes of the solvent- extracted nanoplatelets. The solid fat content (SFC), oil migration value, and storage elastic modulus were also determined. The average crystal size, which was measured in length, of the fat blends with SEFs containing saturated fatty acids (namely, palmitic and stearic acids) was smaller than that of the SEFs containing unsaturated fatty acids (namely, oleic and erucic acids). The effects exerted by these fatty acid moieties on the spherulite size in the corresponding bulk fat blends were observed via polarized microscopy (PLM). The results suggest that nanostructure formation upon the addition of SEF ultimately influenced these aggregated microstructures. Generally, smaller platelets resulted in higher SFC in the fat phase, and a high correlation between the SFC and the G' values in W/O emulsion fats was observed (R² = 0.884) at 30°C. In contrast, the correlation was low at 10℃. Furthermore, samples with larger nanocrystals had a higher propensity for oil migration. Thus, the addition of SEF regulated the fat crystal nanostructure during nucleation and crystal growth, which could ultimately influence the physical properties of commercially manufactured fat products such as margarine.

Stabilization of water-in-oil emulsion of Pulicaria jaubertii extract by ultrasonication: Fabrication, characterization, and storage stability

This study investigated the effect of ultrasonic treatments on the properties and stability of the water-in-oil (W/O) emulsion of Pulicaria jaubertii (PJ) extract. The study used different ultrasound powers (0, 100, 200, 400, and 600 W) at two storage degrees (4 and 25 °C) for 28 days. The findings showed that the emulsifying properties were improved to different extents after ultrasonic treatments. The treatment at 600 W showed optimum particle size, polydispersity index, emulsifying property, viscosity properties, and release of total phenolic content than the other powers. However, the ultrasonic power of 400 W gave positive effects on creaming index and antioxidant release compared to 600 W. The emulsion stored at 4 °C presented higher stability than that stored at 25 °C during the 28 days of storage. Microscopically, the increase in sonication power up to 600 W reduced particle size and decreased flocculation, thus resulted in stable emulsions, which is desirable for its applications in food systems.

Exploration of the natural waxes-tuned crystallization behavior, droplet shape and rheology properties of O/W emulsions

Lipid crystallization in O/W emulsions is essential to control the release of nutrients and to food structuring. While few information is involved in adjusting and controlling the performance of emulsions by adjusting oil phase crystallization behavior. We herein developed a novel strategy for designing lipid crystallization inside oil droplets by natural waxes to modify the O/W emulsion properties. Natural waxes, the bio-based and sustainable materials, displayed a high efficiency in modifying the crystallization behavior, droplet surface and shape, as well as the overall performance of emulsions. Specifically, waxes induced the formation of a new hydrocarbon chain distances of 3.70 and 4.15 Å and slightly decreased the lamellar distance (d₀₀₁) of the single crystallites, thus forming the large and rigid crystals in droplets. Interestingly, these large and rigid crystals in droplets tended to penetrate the interface film, forming the crystal bumps on the droplet surface and facilitating non-spherical shape transformation. The presence of rice bran wax (RW) and carnauba wax (CW) induced the droplet shape into ellipsoid and polyhedron shape, respectively. Furthermore, the uneven interface and non-spherical shape transformation promoted the crystalline droplet-droplet interaction, fabricating a three-dimensional network structure in O/W emulsions. Finally, both linear and nonlinear rheology strongly supported that waxes enhanced the crystalline droplet-droplet interaction and strengthened the network in O/W emulsions. Our findings give a clear insight into the effects of adding natural waxes into oil phase on the crystalline and physical behavior of emulsions, which provides a direction for the design and control of emulsion performance.

Protein-Stabilized Palm-Oil-in-Water Emulsification Using Microchannel Array Devices under Controlled Temperature

Microchannel (MC) emulsification for the preparation of monodisperse oil-in-water (O/W) and water-in-oil-in-water (W/O/W) emulsions containing palm oil as the oil phase was investigated for application as basic material solid/semi-solid lipid microspheres for delivery carriers of nutrients and drugs. Emulsification was characterized by direct observation of droplet generation under various operation conditions, as such, the effects of type and concentration of emulsifiers, emulsification temperature, MC structure, and flow rate of to-be-dispersed phase on droplet generation via MC were investigated. Sodium caseinate (SC) was confirmed as the most suitable emulsifier among the examined emulsifiers, and monodisperse O/W and W/O/W emulsions stabilized by it were successfully obtained with 20 to 40 µm mean diameter (d_m) using different types of MCs.

An Insight into the Solid-State Miscibility of Triacylglycerol Crystals

The crystallization properties of triacylglycerols (TAGs) strongly determine the functional properties of natural lipids. The polymorphic and mixing phase behavior of TAG molecules have long been, and still are, a hot topic of research with special relevance for the cosmetic, pharmaceutical, and food industry. To avoid the difficulties arising from the study of whole real fats, studies at the molecular level on mixtures of a limited number of TAGs has become an indispensable tool to identify the underlying causes of the physical properties in lipid systems. In particular, phase diagrams of binary mixtures of TAGs exhibiting a different degree of heterogeneity (monoacid or mixed fatty acids; molecular symmetry; the presence of cis or trans double bonds) have resulted in a significant breakthrough in our knowledge about structure-interaction-function relationships. The present work aims to provide an overview of the main reports regarding binary and ternary TAG systems, from the early studies to the most recent developments.

Physicochemical characterization and antimicrobial activity in novel systems containing buriti oil and structured lipids nanoemulsions

Buriti oil nanoemulsions were prepared using non-interesterified buriti oil or buriti oil interesterified for 6 or 24 h (NBO, NBO6h, and NBO24 h), respectively. The aim was to investigate the effects of interesterified oils on the physicochemical and biological properties of nanoemulsions. Samples were stored at 4 and 25 °C for 30 days, and their physicochemical properties and biological activities were evaluated. The mean droplet diameter of nanoemulsions ranged from 196 to 270 nm. NBO24 h had the smallest droplet size and was the most stable during the storage period. Furthermore, NBO24 h demonstrating the good oxidative stability, had a high antioxidant capacity, and was less susceptible to droplet aggregation. NBO and NBO24 h had similar biological activity against Gram-negative bacteria (Escherichia coli O157: H7); bacterial growth was inhibited by at least 60% at 3.12 mg mL-1. The nanoemulsions have interesting properties for the production of pharmaceutical, cosmetic, and food formulations with antimicrobial activity.

Ultrasound-mediated interfacial protein adsorption and fat crystallization in cholesterol-reduced lard emulsion

Lard with a substantially reduced cholesterol content through aqueous enzyme extraction is an attractive source of lipid in healthy and nutritious emulsion food product development. The objective of this study was to elucidate the crystallization behavior (4-20 °C) of emulsions prepared from low-cholesterol lard in relation to protein emulsifier (2 and 4% whey protein isolate, WPI) and ultrasound (475 w, 5 min) treatments. The physicochemical properties and fat crystallization pattern of the emulsions were investigated. Emulsions with 4% WPI were superior to those with 2% WPI on interfacial adsorption and crystal size reduction. Ultrasonic treatment of prepared emulsions further decreased fat crystal size, promoted small and uniform crystal distribution, and slightly destabilized emulsions. Protein concentration and ultrasonic treatment had no obvious effect on crystal transition from β' to the more stable β-form based on X-ray diffraction. The melting properties determined by differential scanning calorimetry indicated that emulsified lard had a lower onset melting temperature than bulk lard, and with ultrasound treatment, the melting enthalpy increased remarkably. The ultrasound-induced change in fat crystalline structure and emulsion meta-stability may be valuable to the manufacture of healthy, emulsion-incorporated food products.

Insights into the behavior of six rationally designed peptides based on Escherichia coli's OmpA at the water-dodecane interface

The Escherichia coli's membrane protein OmpA has been identified as a potential biosurfactant due to their amphiphilic nature, and their capacity to stabilize emulsions of dodecane in water. In this study, the influence of surfactant type, concentration, preservation time and droplet size on the crystallization of n-dodecane and water, in oil-in-water emulsions stabilized with six rationally designed Escherichia coli's OmpA-based peptides was investigated. A differential scanning calorimetry (DSC) protocol was established using emulsions stabilized with Tween 20® and Tween 80®. A relationship between the surfactant concentration and the crystallization temperatures of n-dodecane and water was observed, where the crystallization temperatures seem to be dependent on the preservation time. A deconvolution analysis shows that the peak morphology possibly depends on the interactions at the interface because the enthalpic contributions of each Gaussian peak remained similar in emulsions stabilized with the same peptide. Adsorption results show that the main driver for adsorption and thus stabilization of emulsions is polar interactions (e.g. H-bonding) through the hydrophilic parts of the peptides. Those peptides with a preponderance of polar interaction groups distribution (i.e. NH2, COOH, imidazole) showed the highest interfacial activity under favorable pH conditions. This suggests that custom-made peptides whose hydrophilic/hydrophobic regions can be fine-tuned depending on the application can be easily produced with the additional advantage of their biodegradable nature.