Effects of flaxseed gum concentrations and pH values on the stability of oil-in-water emulsions

Unlocking flaxseed oleosomes (oil bodies) potential: Optimal extraction and functional insights through enzymolysis or dehulling treatment

Oleosomes are intracellular vesicles within a phospholipid monolayer membrane and have significant potential for use in various food applications as natural emulsions. Flaxseed, an underexplored yet promising crop, shows promise for oleosome utilization. However, the high mucopolysaccharide content in hulls may pose challenges to the extraction efficiency of natural flaxseed oleosomes (N-FOs). In this study, two pretreatment methods were employed prior to aqueous extraction: enzymatic hydrolysis using a cellulase-pectinase-xylanase cocktail and dehulling. Both pretreatment methods significantly improved the extraction yield, with dehulling flaxseed oleosomes (D-FOs) achieving 51.3 % and enzymatically hydrolyzed flaxseed oleosomes (E-FOs) reaching 53.1 %, representing an increase by a factor of five compared to N-FOs. The average droplet size of E-FOs ranged from 1.5 to 1.7 μm across pH 2.0 to pH 10.0, while the absolute value of the zeta-potential for E-FOs at pH 10.0 was the highest at -39.6 mV. Cryo-SEM imaged that E-FOs and N-FOs exhibited a more complete structure than D-FOs, which might be attributed to the increased electrostatic repulsion generated by flaxseed protein and spatial hindrance of incompletely hydrolyzed polysaccharides. LF-NMR spectra showed shorter T2 values of E-FOBs, confirming increased interactions between residual polysaccharides and oleosomes. The tight and solid-like interfacial film affirmed by the emulsifying activity and rheological results could protect emulsion droplets against flocculation and disproportionation, thus contributing to enhanced emulsification stability. Enzymatic hydrolysis demonstrated a favorable balance between extraction yield and functional properties compared to dehulling or no pretreatment, making it a suitable approach for efficient oleosome extraction from flaxseeds for various plant-based food applications.

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.

High internal phase emulsion stabilized by soy protein isolate-Rutin complex: Rheological properties, bioaccessibility and in vitro release kinetics

High internal phase emulsions (HIPEs) are promising carrier materials for encapsulating and delivering hydrophobic bioactive compounds. By strategically adjusting the composition, particle size, or charge of HIPEs, it is possible to enhance both their stability and the bioaccessibility of hydrophobic polyphenols encapsulated within them. In this study, different soy protein isolate (SPI)-rutin (SPI-R) complexes (formed under various preheating temperatures) were used to stabilize HIPEs, while the particle size, and charge of HIPEs was further adjusted through different homogenization rates. The results demonstrated that an optimal preheating temperature of 70 °C for the complex and a homogenization rate of 15,000 rpm for HIPEs enhanced the stability of the entire emulsion system by producing more uniform and smaller droplet distribution with improved rheological properties. Furthermore, in vitro digestion experiments showed that HIPEs stabilized by the SPI-R complexes (HSR) at optimal homogenization rate had better loading efficiency (98.68 %) and bioaccessibility compared to other groups. Additionally, fitting results from release kinetics confirmed that rutin encapsulated by HSR could achieve sustained release effect. Overall, these findings suggest that HSR has great potential as an effective vehicle for delivering hydrophobic bioactive compounds like rutin within the food industry.

Fabrication and Characterization of Botanical-Based Double-Layered Emulsion: Protection of DHA and Astaxanthin Based on Interface Remodeling

Both DHA and astaxanthin, with multiple conjugated double bonds, are considered as health-promoting molecules. However, their utilizations into food systems are restricted due to their poor water solubility and high oxidizability, plus their certain off-smell. In this study, the interactions between perilla protein isolate (PPI) and flaxseed gum (FG) were firstly investigated using multiple spectroscopies, suggesting that hydrophobic, electrostatic force and hydrogen bonds played important roles. Additionally, double-layer emulsion was constructed by layer-by-layer deposition technology and exhibited preferable effects on masking the fishy smell of algae oil. Calcium ions also showed an improving effect on the elasticity modulus of O/W emulsions and was managed to significantly protect the stability of co-delivered astaxanthin and DHA, without additional antioxidants during storage for 21 days. The vegan system produced in this study may, therefore, be suitable for effective delivery of both ω-3 fatty acid and carotenoids for their further incorporation into food systems, such as plant-based yoghourt, etc.

Construction of lipid-biomacromolecular compounds for loading and delivery of carotenoids: Preparation methods, structural properties, and absorption-enhancing mechanisms

Due to the unstable chemical properties and poor water solubility of carotenoids, their processing adaptation and oral bioavailability are poor, limiting their application in hydrophilic food systems. Lipid-biomacromolecular compounds can be excellent carriers for carotenoid delivery by taking full advantage of the solubilization of lipids to non-polar nutrients and the water dispersion and gastrointestinal controlled release properties of biomacromolecules. This paper reviewed the research progress of lipid-biomacromolecular compounds as encapsulation and delivery carriers of carotenoids and summarized the material selection and preparation methods for biomacromolecular compounds. By considering the interaction between the two, this paper briefly discussed the effect of these compounds on carotenoid water solubility, stability, and bioavailability, emphasizing their delivery effect on carotenoids. Finally, various challenges and future trends of lipid-biomacromolecular compounds as carotenoid delivery carriers were discussed, providing new insight into efficient loading and delivery of carotenoids.

Rheology and stability of concentrated emulsions fabricated by insoluble soybean fiber with few combined-proteins: Influences of homogenization intensity

Insoluble soybean fiber with few proteins, which is extracted from defatted okara by homogeneous combined with alkali treatment, was used to prepare concentrated emulsions. Firstly, insoluble soybean fiber extracted under pH12 was used to fabricate concentrated emulsions containing various particle concentrations and oil volume fractions and the optimized condition was obtained. Subsequently, insoluble soybean fiber extracted under pH12 followed by different homogeneous strengths were utilized. Concentrated emulsions stabilized by insoluble soybean fiber that was subjected to stronger homogenization presented lower absolute values of the ζ-potential about -47.7 mV and average droplet sizes of 37.0 μm approximately. Moreover, these emulsions exhibited a higher viscosity and elastic modulus, thereby providing better stability and less pronounced environmental sensitivities towards either pH 5 or 100 mM NaCl. Overall, results revealed that insoluble soybean fiber with few protein, especially subjected to homogenization during fiber extraction, was well suited to fabricate concentrated emulsions.

A Review of Extraction Techniques and Food Applications of Flaxseed Mucilage

Flaxseed contains significant concentration of mucilage or gum (a type of hydrocolloid). Flaxseed mucilage (FM) predominantly occurs in the outermost layer of the seed's hull and is known to possess numerous health benefits such as delayed gastric emptying, reduced serum cholesterol, and improved glycemic control. FM is typically composed of an arabinoxylan (neutral in nature) and a pectic-like material (acidic in nature). Similar to gum arabic, FM exhibits good water-binding capacity and rheological properties (similar functionality); therefore, FM can be used as its replacement in foods. In this review, an overview of methods used for FM extraction and factors influencing the extraction yield were discussed initially. Thereafter, food applications of FM as gelling agent/gel-strengthening agent, structure-forming agent, stabilizing agent, fat replacer, anti-retrogradation agent, prebiotic, encapsulating agent, edible coatings and films/food packaging material, and emulsifier/emulsion stabilizer were included. At the end, some limitations to its wide application and potential solutions were added.

Rheological and tribological nature of flaxseed gum influenced by concentration and temperature and its application as a coating agent for potato chips

Influence of different concentrations (0.5, 1.0, 2.0, and 3.0% w/v) and temperatures (4, 25, 50, and 75°C) on particle size distribution (PSD) and rheological and tribological characteristics of flaxseed gum (FSG) solutions was investigated. Besides, FSG dispersions (0.5, 1.0, and 2.0% w/v) were used as edible coating and their influence on the quality parameters (oil uptake, moisture loss, texture, and sensory properties) of fried potato chips was studied. All FSG dispersions revealed shear-thinning nature and viscous properties (as G″ > G') that were more dominant at higher concentrations and lower temperatures. The power-law model presented a good fit in demonstrating the flow behavior of FSG dispersions. Concentration was the variable that affected the tribology of FSG dispersions, while temperature had little effect on the tribology. Particle size distribution was increased with the increasing concentration of FSG. FSG dispersions as an edible coating effectively reduced the moisture loss, oil uptake, and hardness properties of potato chips. Practical Application Profiling the influence of concentration and temperature on the rheology and tribology of flaxseed gum is particularly valuable during food processing. The results predict the physical properties of coated potato chips that can support the potential application of flaxseed gum as a coating agent. Today's consumers prefer healthier food products with low caloric, higher fiber content, functional properties, and sensory qualities. Food industries can use FSG as a low-cost natural coating material in terms of economic benefits, consumer acceptance, and providing an inordinate potential both for its protective effect and carrying functional compounds such as antioxidants in their coating matrix.

Improved effect of flaxseed gum on the weakened gelling properties of myofibrillar protein induced by catechin

The effect of flaxseed gum (FG) on the weakened gelling properties of myofibrillar proteins (MP) induced by catechin was investigated. Different levels of FG and catechin were incorporated into MP and the chemical changes of MP were studied; MP emulsions and gels with different levels of FG and catechin were prepared and their properties were studied. Catechin promoted the loss of thiol and the exposure of the hydrophobic groups of MP and increased the particle size and apparent viscosity of emulsions, resulting in a poor gel network. The incorporation of FG enhanced the gel strength, water holding capacity and dynamic rheological properties, which might be attributed to the formation of uniform and stabilized emulsions with high apparent viscosity and the enhanced disulfide cross-linking and hydrophobic interactions during heat-induced gelation. FG could be a potential approach in overcoming the deterioration of protein gels caused by catechin.

Effect of flaxseed gum on the brittleness of oleogels based on candelilla wax

The present study aimed to decrease the brittleness of flaxseed oleogels based on candelilla wax (CLW) in combination with flaxseed gum (FG). Effects of flaxseed gum concentrations (0–0.4%) on the characteristics of flaxseed oleogels including oil binding capacity, textural, thermal, and rheological properties, and crystal polymorphisms were investigated. Higher concentrations (≥0.2%) of FG significantly decreased the textural parameters (e.g., hardness, fracturability) of oleogels (p < 0.05), suggesting that FG could decrease brittleness. Rheological results indicated that all flaxseed oleogels exhibited solid-like characteristics because the elastic modulus was larger than the viscous modulus. The elastic modulus of flaxseed oleogels presented a maximum value at 0.1% gum concentration. Any increase in gum concentration beyond this concentration decreased the elastic modulus. Increasing FG concentration up to 0.4% decreased the enthalpy of flaxseed oleogels during the melting process. The β′-polymorphic form is an orthorhombic perpendicular (O_⊥) subcell structure. Similar β′ crystal forms were observed among flaxseed oleogels, indicating that FG did not affect them negatively. The study showed that the physical properties of flaxseed oleogels based on CLW could be significantly changed by FG addition. These results provided a deeper comprehension of the novel system, which should be considered a new way to obtain healthy fats with better plasticity for food applications.

Oleogels using candelilla wax as a gelling agent and flaxseed gum as a structural modifier: preparation and characterization.

Astaxanthin-loaded emulsion gels stabilized by Maillard reaction products of whey protein and flaxseed gum: Physicochemical characterization and in vitro digestibility

In order to evaluate the effect of ultrasound and Maillard reaction on the physicochemical properties and gastrointestinal fate of astaxanthin-loaded emulsion gels, the Maillard reaction products (MRPs) of whey protein and flaxseed gum (FG) were prepared by traditional or ultrasonic assisted wet-heating. The MRPs obtained by ultrasonic assisted wet-heating had higher grafting degree and more expanded structures evidenced by the browning intensity, fluorescence intensity and circular dichroism (CD) analysis, thus enhancing its functional properties like solubility and emulsifying capacity. The MRPs improved the water holding capacity, encapsulation efficiency, stability of emulsion gels, in which astaxanthin was wrapped as a model bioactive compound. During the simulated digestion process, the bioaccessibility of loaded astaxanthin reached 72.08% for the emulsion gels stabilized by MRPs. The results highlighted the potential of MRPs in improving functionality of protein and as a delivery carrier of bioactive compounds in food industry.

Colloidal Particles in Tuna Head Soup: Chemical Localization, Structural Change, and Antioxidant Property

In this work, chemical localization, structural changes, and antioxidant properties of tuna colloidal particles (TCPs) in boiling tuna head soup were examined. The results demonstrated that TCPs might be core–shell colloidal spherical structures. The hydrophobic core consisted of triglycerides and chloride ions. The hydrophilic shell layer consisted of chloride ions, sodium ions, phospholipids, protein, and glycosyl molecules. Coalescence of TCPs occurred during the boiling process, and water may enter the hydrophobic core of TCPs after the boiling time of 60 min. TCPs had excellent antioxidant properties against H₂O₂-induced human umbilical vein endothelial cell injury. It might be resulted from that TCPs could decrease cell apoptosis proportion and downregulate mRNA levels of endoplasmic reticulum-bounded chaperone protein glucose-related protein (GRP78), C/EBP homologous protein (CHOP), and activating transcription factor-4 (ATF4). This work can provide useful basic information to understand the colloidal system in foods, especially in soup. In addition, it may also promote the potential high-value-added utilization of aquatic by-products.

Using Flammulina velutipes derived chitin-glucan nanofibrils to stabilize palm oil emulsion:A novel food grade Pickering emulsifier

We herein report chitin-glucan nanofibrils from edible mushroom Flammulina velutipes (CGNFs) as a novel stabilizer for palm oil Pickering emulsion (o/w, 30:70, v:v). Generally, these CGNFs being composed of glucose and glucosamine, are threadlike with 4.9 ± 1.2 nm wide and 222.6 ± 91.9 nm long. They were easily absorbed on the oil-water interface to form a compact layer around the oil droplets referring to Pickering emulsion. This emulsion presented shear-thinning and gel-like behaviors, wherein CGNFs concentration had a profound influence on the emulsion volume, droplet size, and stabilization index. Moreover, CGNFs showed an ability to stabilize the emulsion with a minimum of surface coverage approximately 30%. It indicated that moderate concentration of NaCl improved the emulsification effect, and the emulsion were stable in a large range of pH. These CGNFs are easy to prepare, eco-friendly and sustainable, which provides a potential for large-scale application of Pickering emulsion in food and nutraceuticals fields.

Factors determining the surface oil concentration of encapsulated lipid particles: impact of the emulsion oil droplet size

Microencapsulation of oxidation sensitive oils aims to separate lipids from the environmental oxygen by embedding oil droplets in a solid matrix, which builds a physical barrier. Some oil droplets are not fully incorporated and are in contact with the powder surface generating surface oil. It is proposed that the probability of oil droplets being in contact with the particle surface increases with the oil droplet size. The aim of the study is to investigate the impact of the oil droplet size on the encapsulation efficiency (EE). Two sets of feed emulsions differing in the applied homogenization pressure and in the protein to oil ratio were spray dried using a pilot plant spray dryer. The oil droplet size of the emulsion was determined by static light scattering (SLS). In addition, nuclear magnetic resonance (NMR) was used to measure the d3,2 of oil droplets in the emulsion and in the powder before and after surface oil removal. Encapsulates were analyzed regarding aw, moisture content, particle size, oil load and EE. The oil droplet size in the emulsion decreased with increasing protein to oil ratio as well as with the homogenization pressure. Large oil droplets and in particular droplet clusters resulted in more non-encapsulated oil. The experimentally determined EE was in accordance with the theoretical one, calculated based on the droplet and particle diameter. For emulsions with a diameter > 1 µm, the d3,2 decreased in the powder and further by removing the surface oil, which was related to the deformation of oil droplets contributing to the non-encapsulated oil.

Effect of oregano (Origanum vulgare L. ssp. hirtum) and clove (Eugenia spp.) nanoemulsions on Zygosaccharomyces bailii survival in salad dressings

This work aimed to evaluate the in vitro effect of encapsulated oregano and clove essential oils on oil-in-water nanoemulsions against Zygosaccharomyces bailii. The antifungal efficacy of these nanoemulsions and their sensory acceptance were tested in salad dressings. Both essential oils were effective inhibitors against the target yeast, with minimal inhibitory and fungicidal concentrations of 1.75 mg/mL. In the in vitro assay done with the nanoemulsions, no yeast growth was observed for any tested essential oil concentration. In the salad dressings, all the formulations were able to reduce Z. bailii growth compared to the control, and only those samples with 1.95 mg/g of essential oil were capable of inhibiting yeast development after 4 inoculation days. The sensory acceptance of the dressing containing the nanoemulsions was similar to the control dressing in appearance, consistency and colour terms. These results evidence the antifungal activity of oregano and clove nanoemulsions against Z. bailii.

Vitamin E Encapsulation in Plant-Based Nanoemulsions Fabricated Using Dual-Channel Microfluidization: Formation, Stability, and Bioaccessibility

In this study, vitamin E was encapsulated in oil-in-water nanoemulsions fabricated using a dual-channel microfluidizer. A long chain triacylglycerol (corn oil) was used as a carrier oil and a biosurfactant (quillaja saponin) was used as a natural emulsifier. The impact of vitamin-to-carrier oil ratio on the formation, storage stability, and bioaccessibility of the nanoemulsions was determined. The lipid droplet size formed during homogenization increased with increasing vitamin content, which was attributed to a large increase in lipid phase viscosity. The storage stability of the nanoemulsions decreased as the vitamin content increased because the larger lipid droplets creamed faster. The rate and extent of lipid hydrolysis in the small intestine decreased as the vitamin content increased, probably because the vitamin molecules inhibited the ability of lipase to reach the triacylglycerols inside the lipid droplets. Vitamin bioaccessibility decreased as the vitamin level in the lipid phase increased, which was attributed to the reduced level of mixed micelles available to solubilize the tocopherols. The optimized nanoemulsion-based delivery system led to a relatively high vitamin bioaccessibility (53.9%). This research provides valuable information for optimizing delivery systems to increase the bioaccessibility of oil-soluble vitamins.

Formulation and optimization of pH sensitive drug releasing O/W emulsions using Albizia lebbeck L. seed polysaccharide

Smart polymers, one of the class of polymers with extensive growth in the last few decades due to their wide applications in drug targeting and controlled delivery systems. With this in mind, the aim of the present study is to design and formulate smart releasing o/w emulsion by using Albizia lebbeck L. seed polysaccharide (ALPS). For this purpose, the physicochemical and drug release characteristics like emulsion capacity (EC), emulsion stability (ES), viscosity, microscopy, zeta potential, polydispersity index (PDI) and in-vitro drug release were performed. The EC and ES values were found to increase with an increased concentration of ALPS. The emulsion formulations were statistically designed by using 3² full factorial design. All the emulsions showed a shear-thinning behavior. The zeta potential and polydispersity index were found to be in the range of -35.83 mV to -19.00 mV and 0.232-1.000 respectively. Further, the percent cumulative drug release of the emulsions at 8 h was found to be in the range of 30.19-82.65%. The drug release profile exhibited zero order release kinetics. In conclusion, the ALPS can be used as a natural emulsifier and smart polymer for the preparation of pH sensitive emulsions in drug delivery systems.