Modulation of stability, rheological properties, and microstructure of heteroaggregated emulsion: Influence of oil content

Micellar casein were constructed to improve the encapsulation efficiency of algae oil docosahexaenoic acid by transglutaminase-coupled phosphoserine peptide chelating with Ca2

Micelle systems using safe food-grade biopolymers are of particular interest for the encapsulation and delivery of nutrition components. Micellar casein (MC) was assembled using transglutaminase (TGase) to couple with phosphoserine peptide, which enhance the stability of docosahexaenoic acid (DHA) from algae oil. The mechanism behind the construction of MC-phosphoserine peptide and the encapsulation of DHA was explored. The results showed that the average particle size of the MC-phosphoserine peptide was 155.09 nm, when the mass ratio of polypeptide was 3 %, TGase activity was 4.5 U and pH 6.5. The recombinant MC-phosphoserine peptide system can improve the emulsification and digestive stability of DHA compared to the control MC. Chelation interaction between phosphoserine peptide and MC played an important role in increasing the stabilization reassembly MC. The phosphoserine peptide high calcium-binding capacity enhances encapsulation efficiency and digestion sustained-release in self-assembled micelles for fat-soluble substances.

The impact of flaxseed gum addition on oil absorption of deep-fried dough sticks and its underlying mechanism

The present study investigated the effect of flaxseed gum (FG) in wheat flour on the oil absorption capacity of deep-fried dough sticks (DFDS) and the underlying mechanism. Results showed that the addition of FG limited the oil uptake of the dough during the deep-frying process. The lowest oil content in DFDS was observed in the group in which 1.0 % FG was added. To elucidate the underlying mechanism, the rheological properties of the dough, secondary structure of protein, covalent and noncovalent bonds, and the microstructure of gluten were investigated. The viscoelasticity, covalent and noncovalent bonds of gluten increased with the addition of FG. In terms of the secondary structure of gluten, the β-sheets content increased, while the content of α-helices and β-turns decreased with the addition of FG. The results regarding the microstructure indicated that there were fewer breakages in the dough with FG, which showed a denser gluten network. The denser gluten network contributed to the reduced ability of oil uptake in DFDS. Interestingly, the lowest oil content and the highest moisture content of DFDS were observed when 1.0 % FG was added, resulting in a 30.27 % decrease in oil content and an 11.67 % increase in moisture content compared with the control group. Additionally, both the covalent and noncovalent bonds in gluten protein were the strongest with 1.0 % FG addition, where the β-sheets content was highest. This study revealed the effect of FG on the formation of the gluten network, offering a potential approach for the production of high-quality DFDS.

Yolk and Casein Sequence Self-Assembly for Low-Oil Emulsion Gel and Its Application in Low-Fat Mayonnaise

High dietary fat food such as mayonnaise (70-80% oil content) can induce obesity and cardiovascular diseases, thus reducing their oil content is required. However, the development of low-fat mayonnaise is still a big challenge since reducing oil content will increase the fluidity, induce phase separation and decrease the stability of mayonnaise. Herein, we provide a novel strategy for developing yolk-casein-based low-fat mayonnaise (30% oil content) with a similar texture to commercial high-fat mayonnaise through post-acidification. Unexpectedly, compared with pre-acid-treated low-fat mayonnaise, the G' and viscosity of the post-acid-treated low-fat mayonnaise were significantly improved by 77.80% and 90.18%, respectively. The semisolid properties required for low-fat mayonnaise were realized by forming a dense yolk-casein self-assembly network structure. This study provides a novel perspective for constructing edible soft-solid products with low fat intake.

Impact of lecithin on the lubrication properties of konjac glucomannan gels

The effects of lecithin addition on the properties of konjac glucomannan (KGM) hydrogels prepared by controlled heating were investigated. Weak hydrogels were formed at 1 % KGM, which contained relatively thick strands. The shear viscosity and shear modulus of the hydrogels increased with increasing KGM concentration. The pure KGM hydrogels exhibited relatively poor boundary lubrication at all polysaccharide concentrations studied. The inclusion of lecithin (0.001 % to 0.20 %) in the KGM hydrogels appreciably altered their rheological properties, which could be modulated by varying the lecithin/KGM ratio. Microstructural analysis showed that lecithin caused a substantial restructuring of the strands in the hydrogel network. Lecithin was also found to be a highly effective lubricant in the KGM hydrogels. Incorporation of trace amounts of lecithin led to a significant improvement in the lubricating properties of the KGM hydrogels, especially boundary lubrication. Fourier transform infrared (FTIR) and differential canning calorimetry (DSC) analyses provided information about the molecular interactions between the lecithin and KGM molecules. The ability of lecithin to increase the lubricating performance of the KGM hydrogels was mainly attributed to the adsorption of phospholipid-biopolymer complexes onto solid surfaces, which reduced the friction between them.

The role of fat content in coconut milk: Stability and digestive properties

The fat in coconut milk contributes to unique flavour, while increasing fat content affects stability of the coconut milk. In this study, coconut water and fat were separated, recombined, and homogenized to obtain coconut milk with different fat contents (0-20 %). Emulsifying properties, stability, and digestibility of coconut milk with different fat contents were comprehensively evaluated. The results showed that as the fat content increased from 0 to 20 %, the droplet size increased from 2.18 to 4.70 μm and the viscosity showed an increasing trend. During storage and freeze-thaw, coconut milk with 5 % and 10 % fat content showed excellent stability. In addition, coconut milk with 10 % fat content had superior fat digestibility, which was related to high affinity of pancrelipase. In short, this study revealed that fat content below 10 % can withstand environmental factors such as storage, lipid oxidation, and freeze-thaw, which can be accurately developed as coconut milk products.

Spray-drying and rehydration on β-carotene encapsulated Pickering emulsion with chitosan and seaweed polyphenol

The spray-drying process to generate microcapsules from Pickering emulsions needs high temperatures, leading to instability of emulsions and degradation of encapsulated thermosensitive compounds (β-carotene). However, these effects may be attenuated by the introduction of seaweed polyphenols into the emulsion interfacial layers, although the effects underlying this protective mechanism have not been explored. This study evaluates the effects of spray-drying/rehydration on the morphology, encapsulation efficiency, redispersibility, and stability of β-carotene loaded Pickering emulsions stabilized by chitosan (PESC) and Pickering emulsions stabilized by chitosan/seaweed polyphenols (PESCSP). The encapsulation efficiency of β-carotene in PESCSP microcapsules (61.13 %) was higher than PESC (53.91 %). Rehydrated PESCSP exhibited more regular droplet size distribution, higher stability, stronger 3D network morphology, and lower redispersibility index (1.5) compared to rehydrated PESC. Analyses of interfacial layers of emulsions revealed that chitosan covalently bound fatty acids at their hydrophobic side. Polyphenols were linked to chitosan at the hydrophilic side of emulsions through hydrogen bonds, providing 3D network between droplets and antioxidant activities to inhibit the degradation of β-carotene. This study emphasized the role of polyphenols in the interfacial layers of Pickering emulsions for the development of efficient delivery systems and protection of β-carotene and other thermosensitive bioactive compounds during spray-drying and rehydration.

The Effects of a Crosslinking Agent on the Microrheological Properties and Cellular Structure of Silicone Rubber Foam Prepared via a Green Process

Chemical foaming technology is widely used in the preparation of silicone rubber foam and is attributable to its one-step molding capability and eco-friendly production processes. The microrheological properties of silicone rubber play a pivotal role during the foaming process. In this study, Rheolaser Lab (Formulaction, Toulouse, France) was used to conduct in situ examinations for the influence of a crosslinking agent on the microrheological properties of silicone rubber foam for the first time. This study monitors the entire reaction process of silicone rubber foam from liquid to solid, as well as the matching of crosslinking and foaming reactions. Various parameters, including solid-liquid balance, elasticity index, and macroscopic viscosity index, are measured to analyze the microrheological properties of silicone rubber foam. The results show that the silicone rubber foam exhibits good microrheological properties, thereby demonstrating excellent performance at a crosslinking agent content of 2%. Through adjusting the experimental conditions, a sustainable and efficient approach was proposed for better cellular structure control in the industrial preparation of silicone rubber foam.

Physicochemical properties of soybean β-conglycinin-based films affected by linoleic acid

To explore the interaction between lipids and proteins during emulsion film formation, the linoleic acid concentration effects on the physicochemical properties of soybean β-conglycinin (7S) films were studied. The viscosity and size of oil droplets in the film-forming solution gradually increased with the increasing linoleic acid concentration. As the linoleic acid concentration increased, the number of oil droplets on the film surfaces and elongation at break of films gradually increased, whereas the tensile strength decreased. The films containing 20% linoleic acid had the highest water vapor permeability value, which was decreased by increasing or decreasing the linoleic acid concentration. According to the molecular dynamics simulation and chemical interactions, 7S could be adsorbed at the linoleic acid interface and bind stably, resulting in the decreased ionic and hydrogen bonds but the increased hydrophobic interactions and covalent bonds among proteins in the films.

Multiscale combined techniques for evaluating emulsion stability: A critical review

Emulsions are multiscale and thermodynamically unstable systems which will undergo various unstable processes over time. The behavior of emulsifier molecules at the oil-water interface and the properties of the interfacial film are very important to the stability of the emulsion. In this paper, we mainly discussed the instability phenomena and mechanisms of emulsions, the effects of interfacial films on the long-term stability of emulsions and summarized a set of systematic multiscale combined methods for studying emulsion stability, including droplet size and distribution, zeta-potential, the continuous phase viscosity, adsorption mass and thickness of the interfacial film, interfacial dilatational rheology, interfacial shear rheology, particle tracking microrheology, visualization technologies of the interfacial film, molecular dynamics simulation and the quantitative evaluation methods of emulsion stability. This review provides the latest research progress and a set of systematic multiscale combined techniques and methods for researchers who are committed to the study of oil-water interface and emulsion stability. In addition, this review has important guiding significances for designing and customizing interfacial films with different properties, so as to obtain emulsion-based delivery systems with varying stability, oil digestibility and bioactive substance utilization.

Stability, Structure, Rheological Properties, and Tribology of Flaxseed Gum Filled with Rice Bran Oil Bodies

In this study, rice bran oil bodies (RBOBs) were filled with varying concentrations of flaxseed gum (FG) to construct an RBOB-FG emulsion-filled gel system. The particle size distribution, zeta potential, physical stability, and microstructure were measured and observed. The molecular interaction of RBOBs and FG was studied by Fourier transform infrared spectroscopy (FTIR). In addition, the rheological and the tribology properties of the RBOB-FG emulsion-filled gels were evaluated. We found that the dispersibility and stability of the RBOB droplets was improved by FG hydrogel, and the electrostatic repulsion of the system was enhanced. FTIR analysis indicated that the hydrogen bonds and intermolecular forces were the major driving forces in the formation of RBOB-FG emulsion-filled gel. An emulsion-filled gel-like structure was formed, which further improved the rheological properties, with increased firmness, storage modulus values, and viscoelasticity, forming thermally stable networks. In the tribological test, with increased FG concentration, the friction coefficient (μ) decreased. The elasticity of RBOB-FG emulsion-filled gels and the ball-bearing effect led to a minimum boundary friction coefficient (μ). These results might contribute to the development of oil-body-based functional ingredients for applications in plant-based foods as fat replacements and delivery systems.

A comparison between silicone free and silicone-based emulsions: technological features and in vivo evaluation

Objective

Nowadays, the use of silicones in cosmetic formulation is still controversial, given that “natural” or “biodegradable” components are preferred. Often, the exclusion and/or the discrimination of these excipients from cosmetic field are unmotivated because all things cannot be painted with the same brush. Hence, we want to bring to light and underline the advantages of including silicones in cosmetic emulsions, refuting and debunking some myths related to their use.

Methods

Silicone‐free and silicone‐based emulsions were obtained within an easy homogenization process. Droplet size distribution was assessed by laser diffraction particle size analyser Mastersizer 2000™, and by optical microscopy. The long‐time stability profiles were investigated thanks to the optical analyser Turbiscan® Lab Expert. Diffusing wave spectroscopy (DWS) by Rheolaser Master™ and frequency sweep measurements by Kinexus® Pro Rotational Rheometer were carried out to assess a full rheological characterization. In vivo studies were carried out by the evaluation of Trans Epidermal Water Loss (TEWL) over time on healthy human volunteers. A skin feeling rating was collected from the same volunteers by questionnaire.

Results

From size distribution analysis, a better coherence of data appeared for silicone‐based emulsion, as the size of the droplets was kept unchanged after 1 month, as well as the uniformity parameter. Morphological investigation confirmed a homogenous droplet distribution for both samples. Silicones enhanced the viscosity, compactness and strength of the cream, providing a suitable stability profile both at room temperature and when heated at 40°C. The solid‐like viscoelastic behaviour was assessed in the presence of dynamic oscillatory stresses. The monitoring of TEWL over time demonstrated non‐occlusive properties of emulsions containing silicones, the values of which were comparable to the negative control. Silicone‐based emulsions gained higher scores from the volunteers in silkiness, freshness and softness features, while lower scores were obtained in greasiness compared to silicone‐free emulsions. No cases of irritation were recorded by the candidates.

Conclusion

The presence of specific silicones inside a cosmetic product improved its technological characteristics. The rheological identity and the stability feature showed the real suitability of prepared emulsion as a cosmetic product. Moreover, this study demonstrated that silicone‐based emulsions are safe for the skin and did not cause skin occlusion. Improved skin sensations are registered by potential consumers when silicones are included in the formulation.

In situ insight into the self-assembly evolution of ABA-type block copolymers in water during the gelation process using infrared spectroscopy and near-infrared spectroscopy

As a kind of thermo-responsive hydrogel, amphiphilic block copolymers are widely investigated. However, the molecular mechanism of their structural change during the gelation process is still limited. Here, a well-controlled triblock copolymer poly(N,N-dimethylacrylamide)-b-poly(diacetone acrylamide)-b-poly(N,N-dimethylacrylamide) (PDMAA-b-PDAAM-b-PDMAA) was synthesized. Its optical microrheology results suggest a gelation temperature range from 42 to 50 °C, showing a transition from viscosity to elasticity. The morphological transition from spheres to worms occurs. Temperature-dependent IR spectra through two-dimensional correlation spectroscopy (2D-COS) and the Gaussian fitting technique were analyzed to obtain the transition information of the molecular structure within the triblock copolymer. The N-way principal component analysis (NPCA) on the temperature-dependent NIR spectra was performed to understand the molecular interaction between water and the copolymer. The intramolecular hydrogen bonds within the hydrophobic PDAAM block tend to dissociate with temperature, resulting in improved hydration and a relative volume increase of the PDAAM block. The dissociation of intermolecular hydrogen bonds within the PDAAM block was the driving force for the morphological transition. Moreover, the hydrophilic PDMAA block dehydrates with temperature, and three stages can be found. The dehydration rate of the second stage with temperature from 42 to 50 °C was obviously higher than those in the lower (first stage) and higher (third stage) temperature ranges.

Stability, Microstructure, and Rheological Properties of CaCO3 S/O/W Calcium-Lipid Emulsions

Calcium carbonate (CaCO₃) is a commonly used fortified calcium, but poor suspension stability and easy precipitation seriously limited its food processing and products application. The formation of CaCO₃ loaded microparticles based on the form of solid/oil/water (S/O/W) emulsion is a promising method to improve the dispersion stability of CaCO₃ in liquid food. In this study, CaCO₃, soybean oil, and sodium caseinate (NaCas) were used as the solid, oil, and W phase, respectively. The fabrication involved two steps: the S/O emulsion was prepared by adding CaCO₃ into soybean oil by magnetic stirring and high-speed shearing, and then put the S/O crude emulsion into NaCas solution (W phase) to obtain S/O/W emulsion by high-speed blender. The particle size distribution, zeta potential, stability of the microsphere, infrared spectral analysis, and XRD of the S/O/W calcium-lipid microsphere were explored. The stability and rheological mechanism of S/O/W calcium-lipid emulsion were investigated by combining the microstructure, shear rheological, and microrheological properties. It was found that the emulsion particles have more uniform particle size distribution and no aggregation, and the stability of the emulsion was improved with increasing the content of NaCas. The mean square displacement (MSD) curve and solid-liquid equilibrium (SLB) value of S/O/W emulsion increased with the increase in NaCas concentration, and the viscosity behavior is dominant. The results of confocal laser microscopy (CLSM) and cryo-scanning electron microscopy (Cryo-SEM) showed that the three-dimensional network structure of S/O/W emulsions was more compact, and the embedding effect of calcium carbonate (CaCO₃) was slightly improved with the increase in NaCas concentration. According to infrared spectrum and XDR analysis, the addition of CaCO₃ into the emulsion system caused crystal structure distortion. This study provides a reference for solving the dispersibility of insoluble calcium salt in liquid food.

Novel γ-cyclodextrin-metal-organic frameworks for encapsulation of curcumin with improved loading capacity, physicochemical stability and controlled release properties

A safe and biodegradable γ-cyclodextrin-metal-organic-frameworks (γ-CD-MOFs) was successfully synthesized by using an improved hydrothermal method. In this study, curcumin (Cur) was chosen for testing the encapsulation stability and release performance of γ-CD-MOFs. Results of the crystal structure measurement indicated that the encapsulated curcumin within γ-CD-MOFs via van der Waals forces, hydrophobic interactions and hydrogen bonding was failed to disturb the inherent microtopography and crystallinity of γ-CD-MOFs. Compared to individual γ-CD, the γ-CD-MOFs exhibited improved loading capacity, physicochemical stability as well as controlled-release property in simulated digestion, and hence can be regarded as effective carriers for curcumin. Curcumin-loaded γ-CD-MOFs with a Cur : γ-CD-MOFs mass ratio of 2:3 (Cur-CD-MOFs/3), which showed the highest encapsulation efficiency (67.31 ± 2.25%), improved physicochemical stability and controlled-release performance, was selected for further research and industrialization. Our results demonstrate that γ-CD-MOFs can be regarded as a promising novel carrier for the delivery of curcumin or other hydrophobic nutraceuticals.

The Stability, Microstructure, and Microrheological Properties of Monascus Pigment Double Emulsions Stabilized by Polyglycerol Polyricinoleate and Soybean Protein Isolate

Monascus pigment is a natural food pigment and is commonly used for coloring and as antiseptic of cured meat products, confectionery, cakes, and beverages. However, Monascus pigment is sensitive to environmental conditions. The main aim of this study was to investigate the effect of polyglycerol polyricinoleate (PGPR) and soy protein isolate (SPI) on the particle size, zeta potential, physical stability, microstructure, and microrheological properties of Monascus pigment double emulsions. The effects of ionic strength, heating, and freeze thawing treatment on the stabilities of Monascus pigment double emulsions were also characterized. It was found that the optimum PGPR and SPI concentrations for fabricating Monascus pigment double emulsion were 3.6 and 3.0 wt%, respectively. The fabricated Monascus pigment double emulsion was composed of fine particles with narrow and uniform size distributions. Microrheological property results suggested that the elastic characteristic of the Monascus pigment double emulsion was dominated with increasing PGPR and SPI contents. It was mainly due to the increased collision and interaction between the droplets during the movement resulting in force increasing. Monascus pigment double emulsions with <5 mM CaCl2 prevented calcium to destroy the physical stability of emulsions, while Monascus pigment double emulsions with more than 10 mM CaCl2 formed creaming. After freeze thawing treatment, creaming occurred in Monascus pigment double emulsion. However, it was stable against heating treatment due to heating leading to a dense network structure. It could be contributed to the practical applications of Monascus pigment double emulsions in food products.