Insight into the oil polarity impact on interfacial properties of myofibrillar protein

Influences of different ultrasonic treatment intensities on the molecular chain conformation and interfacial behavior of sugar beet pectin

In this study, the effects of different ultrasonic treatment intensities (57, 170, and 283 W/cm2) on the chemical composition, molecular chain characteristics, crystal structure, micromorphology, interfacial adsorption behavior and emulsifying properties of sugar beet pectin (SBP) were investigated. Ultrasonic treatment did not change the types of SBP monosaccharides, but it had impacts on their various monosaccharide contents. Moreover, the feruloylated, acetyl, and methoxy groups of SBP also undergo varying degrees of changes. The increase in ultrasonic treatment intensity led to transition in the molecular chain conformation of SBP from rigid semi-flexible chains to flexible chains, accompanied by modification in its crystal structure. Microstructural analysis of SBP confirmed the significant change in molecular chain conformation. Modified SBP could form an elastic interfacial film with higher deformation resistance on the oil-water interface. The SBP sample modified with 170 W/cm2 exhibited better emulsifying properties owing to its better interfacial adsorption behavior. Moreover, the emulsions prepared with modified SBP exhibited better stability capability under different environmental stresses (pH value, salt ion concentration, heating temperature and freeze-thaw treatment). The results revealed that the ultrasonic technology is useful to improve the emulsifying properties of SBP.

Relationship between the interfacial properties of lactoferrin-(-)-epigallocatechin-3-gallate covalent complex and the macroscopic properties of emulsions

This study explored the relationship between the interfacial behavior of lactoferrin-(-)-epigallocatechin-3-gallate covalent complex (LF-EGCG) and the stability of high internal phase Pickering emulsions (HIPPEs). The formation of covalent bond between lactoferrin and polyphenol was verified by the increase in molecular weight. In LF-EGCG group, the surface hydrophobicity, interfacial pressure, and adsorption rate were decreased, while the molecular flexibility, interfacial film viscoelasticity, and interfacial protein content were increased. Meanwhile, LF-EGCG HIPPE possessed reduced droplet size, increased ζ-potential and stability. Rheology showed the viscoelasticity, structural recovery and gel strength of LF-EGCG HIPPE were improved, giving HIPPE inks better 3D printing integrity and clarity. Moreover, the free fatty acids (FFA) release of LF-EGCG HIPPE (62.6%) was higher than that of the oil group (50.1%). Therefore, covalent treatment effectively improved the interfacial properties of protein particles and the stability of HIPPEs. The macroscopic properties of HIPPEs were positively regulated by the interfacial properties of protein particles. The result suggested that the stability of emulsions can be improved by regulating the interfacial properties of particles.

Understanding the textural enhancement of low-salt myofibrillar protein gels filled with pea protein pre-emulsions through interfacial behavior: Effects of structural modification and oil phase polarity

This study investigated the effects of pea protein pre-emulsions containing triglyceride- or diglyceride-oil on the emulsifying and gelling properties of low-salt myofibrillar protein (MP). Pea protein isolates treated with pH12-shifting (PPIpH) or ultrasonication (PPIU) demonstrated superior initial interfacial adsorption and higher final interfacial pressure than native pea protein. Within MP/PPI blends, an increased ratio of MP led to a decrease in interfacial pressure, while simultaneously enhancing film elasticity at both polar and non-polar interfaces. Polar diglyceride promoted protein adsorption and fostered interfacial interactions between modified pea proteins and MP, enhancing the cross-linking of transglutaminase (TG) in the composite emulsion gels. Combining diglyceride-type PPIU and PPIpH emulsions with TG increased gel strength to 0.58 N and 0.63 N, respectively, from an initial 0.33 N, yielding a denser protein network with uniformly dispersed oil droplets. Therefore, the utilization of diglyceride and modified PPI can serve as structural enhancers in comminuted meat products.

Assessment of the impact of whey protein hydrolysate on myofibrillar proteins in surimi during repeated freeze-thaw cycles: Quality enhancement and antifreeze potential

The quality of surimi, widely used in processed seafood, is compromised by freeze-thaw cycles, leading to protein denaturation and oxidative degradation. The objective of this study is to explore the effects of adding natural whey peptide hydrolysate (WPH) on the myofibrillar proteins of repeatedly freeze-thawed surimi. Results indicated surimi treated with 15% WPH exhibited only a 128% increase in surface hydrophobicity and a maximum peroxide value of 7.84 μg/kg, significantly lower than the control group. Additionally, salt-soluble protein content, emulsification activity, and stability decreased with the increase in freeze-thaw cycles. With a 15% WPH offering the most significant protective effect, evidenced by reductions of only 25.02%, 42.52% and 37.02% in salt-soluble protein content, emulsification activity, and stability, respectively. These outcomes demonstrate that WPH effectively reduces protein denaturation during repeated freeze-thaw processes. Future research should explore the molecular mechanisms underlying WPH's protective effects and evaluate their applicability in other food systems.

Phosphate type dependent phosphorylation on the interfacial and emulsion stabilizing behaviors of goose liver protein: Perspective of protein charging

Elucidation on the emulsifying behaviors of goose liver protein (GLP) from interfacial perspective was scarce when protein charging was altered. This work aimed to elucidate the role of phosphorylation on the interfacial associative interaction and then emulsion stabilizing properties of GLP using three structurally relevant phosphates of sodium trimetaphosphate (STMP), sodium tripolyphosphate (STPP) and sodium pyrophosphate (TSPP). A monotonic increment of protein charging treated from STMP, STPP to TSPP caused progressively increased particle de-aggregation, surface hydrophobicity and structural flexibility of GLP. Compared with STMP and TSPP, STPP phosphorylation rendered the most strengthened interfacial equilibrium pressure (11.98 ± 0.24 mN/m) due to sufficient unfolding but moderated charging character conveyed. Desorption curve and interfacial protein microstructure indicated that STPP phosphorylation caused the highest interfacial connectivity between proteins adsorbed onto the same droplet, as was also verified by interfacial elastic modulus (10.3 ± 0.21 mN/m). STPP treated GLP also yielded lowest droplet size (8.16 ± 0.10 μm), flocculation (8.18%) and Turbiscan stability index (8.78 ± 0.36) of emulsion but most improved microrheological properties. Overall, phosphorylation functioned itself in fortifying the intradroplet protein-protein interaction but restraining the interdroplet aggregation, and STPP phosphorylation endowed the protein with most enhanced interfacial stabilization and emulsifying efficiency.

Salinity-Driven Interface Self-Assembly of a Biological Amphiphilic Emulsifier to Form Stable Janus Core-Shell Emulsion for Enhancing Agrichemical Delivery

Agrichemical losses are a severe threat to the ecological environment. Additionally, some agrichemical compounds contain abundant salt, which increases the instability of formulations, leading to a lower agrichemical utilization and soil hardening. Fortunately, the biological amphiphilic emulsifier sodium deoxycholate alleviates these problems by forming stable Janus core-shell emulsions through salinity-driven interfacial self-assembly. According to the interfacial behavior, dilational rheology, and molecular dynamics simulations, Janus-emulsion molecules are more closely arranged than traditional-emulsion molecules and generate an oil-water interfacial film that transforms into a gel film. In addition, at the same spray volume, the deposition area of the Janus emulsion increased by 37.70% compared with that of the traditional emulsion. Owing to the topology effect and deformation, the Janus emulsion adheres to rice micropapillae, achieving better flush resistance. Meanwhile, based on response of the Janus emulsion to stimulation by carbon dioxide (CO2), the emulsion lost to the soil can form a rigid shell for inhibiting the release of pesticides and metal ions from harming the soil. The pyraclostrobin release rate decreased by 50.89% at 4 h after the Janus emulsion was exposed to CO2. The Chao1 index of the Janus emulsion was increased by 12.49% as compared to coconut oil delivery in soil microbial community. The Janus emulsion ingested by harmful organisms can be effectively absorbed in the intestine to achieve better control effects. This study provides a simple and effective strategy, which turns waste into treasure, by combining metal ions in agrichemicals with natural amphiphilic molecules to prepare stable emulsions for enhancing agrichemical rainfastness and weakening environmental risk.

Study on stabilized mechanism of high internal phase Pickering emulsions based on commercial yeast proteins: Modulating the characteristics of Pickering particle via sonication

The primary significance of this work is that the commercial yeast proteins particles were successfully used to characterize the high internal phase Pickering emulsions (HIPPEs). The different sonication time (0,3,7,11,15 min) was used to modulate the structure and interface characteristics of yeast proteins (YPs) that as Pickering particles. Immediately afterward, the influence of YPs particles prepared at different sonication time on the rheological behavior and coalescence mechanism of HIPPEs was investigated. The results indicate that the YPs sonicated for 7 min exhibited a more relaxed molecular structures and conformation, the smallest particle size, the highest H0 and optimal amphiphilicity (the three-phase contact (θ) was 88.91°). The transition from extended to compact conformations of YPs occurred when the sonication time exceeded 7 min, resulting in an augmentation of size of YPs particles, a reduction in surface hydrophobicity (H0), and an elevation in hydrophilicity. The HIPPEs stabilized by YPs particles sonicated for 7 min exhibited the highest adsorption interface protein percentage and a more homogeneous three-dimensional (3D) protein network, resulting in the smallest droplet size and the highest storage (G'). The HIPPEs sample that stabilized by YPs particles sonicated for 15 min showed the lowest adsorption protein percentage. This caused a reduction in the thickness of its interface protein layer and an enlargement in the droplet diameter (D [3,2]). It was prone to droplet coalescence according to the equation used to evaluate the coalescence probability of droplets (Eq (2)). And the non-adsorbed YPs particles form larger aggregation structures in the continuous phase and act as "structural agents" in 3D protein network. Therefore, mechanistically, the interface protein layer formed by YPs particles sonicated 7 min contributed more to HIPPEs stability. Whereas the "structural agents" contributed more to HIPPEs stability when the sonication time exceeded 7 min. The present results shed important new light on the application of commercial YPs in the functional food fields, acting as an available and effective alternative protein.

Improved emulsifying properties of water-soluble myofibrillar proteins at acidic pH conditions: Emphasizing pH-regulated electrostatic interactions with chitosan

Water-soluble muscle protein with enhanced functionalities has attracted great interest for low-salt food design. Electrostatic interactions of chitosan (CS) with myofibrillar proteins (MP) in water-aqueous solution at acidic pHs (4.0-6.5) were investigated, and how pH regulated complex formation, microstructures, conformation changes, and emulsifying capacity was systematically explored. At pH 4.0-4.5, MP and CS were positively charged and displayed a co-soluble system, exhibiting small particles and high solubility. When the pH increased to near the isoelectric point (pI) of MP (pH 5.0-6.0), electrostatic interactions largely inhibited the aggregation of MP by forming smaller particle complexes. The flexible structures and improved amphiphilic properties promoted protein absorption at the oil-water interface, further improving the emulsion stability. When the pH increased to 6.5, large aggregates were formed causing poor functionalities. This study could provide great insights to further exploit meat-protein-based low-salt functional foods in novel food design.

Modulating the properties of myofibrillar proteins-stabilized high internal phase emulsions using chitosan for enhanced 3D-printed foods

The 3D printability of myofibrillar proteins (MP)-based high internal phase emulsions (HIPEs) is a concern. This study investigated the influence of chitosan (CS) concentrations (0-1.5 wt%) on the physicochemical properties, microstructure, rheological properties, and stability of MP-based HIPEs. Results showed that the interaction between MP and CS efficiently modulated the formation of HIPEs by modifying interfacial tension and network structure. The addition of CS (≤ 0.9 wt%, especially at 0.6 wt%) acted as a spatial barrier, filling the network between droplets, which triggered electrostatic repulsion between CS and MP particles, enhancing MP's interfacial adsorption capacity. Consequently, droplet sizes decreased, emulsion stability increased, and HIPEs became more stable during freeze-thaw cycles, centrifugation, and heat treatment. The rheological analysis further demonstrated that the low energy storage modulus (G', 330.7 Pa) of MP-based HIPEs exhibited sagging and deformation during the self-supporting phase. However, adding CS (0.6 wt%) significantly increased the G' (1034 Pa) of MP-based HIPEs. Conversely, increasing viscosity and spatial resistance attributed to CS (> 0.9 wt%) noticeably caused larger droplet sizes, thereby diminishing the printability of MP-based HIPEs. These findings provide a promising strategy for developing high-performance and consumer-satisfaction 3D printing inks using MP-stabilized HIPEs.

Effects of limited enzymatic hydrolysis and polysaccharide addition on the physicochemical properties of emulsions stabilized with duck myofibrillar protein under low-salt conditions

This study aimed to investigate the role of hydrolysis and guar gum (GG) participation on the emulsification of the duck myofibrillar protein (MP) and the related stability of oil-in-water emulsion in low-salt condition. Emulsions were prepared using one of each or both treatments, and that prepared with trypsin hydrolysis and GG (T-GG) exhibited the highest stability. FTIR analysis confirmed the hydrogen bond interactions between the system components. T-GG treatment improved emulsion properties and decreased oil droplet size. Moreover, CLSM indicated that aggregation of T-GG oil droplets was prevented. Physical stability was assessed such as Turbiscan stability index, creaming index, and rheological properties. The adsorbed percentage for T-GG was the lowest. However, interfacial tension, droplet size, stability, and peroxide value analyses indicated that a denser interfacial membrane structure is formed with T-GG. Thus, T-GG treatment could be applied in the food industry, such as in nutrient delivery systems and fat mimetics.

Phenolic structure dependent interaction onto modified goose liver protein enhanced by pH shifting: Modulations on protein interfacial and emulsifying properties

The appropriateness of animal by-product proteins as emulsifiers is barely explored compared to their meat counterparts. This paper focused on improving interfacial and emulsifying properties of modified goose liver protein using three structurally relevant polyphenols either enhanced by pH shifting (P-catechin, P-quercetin and P-rutin) or not (catechin, quercetin and rutin). Due to its high hydrophobicity and limited steric hindrance, quercetin was more sufficient to hydrophobically interact (ΔH > 0, ΔS > 0) with MGLP than catechin and rutin. Results showed that polyphenol interactive affinity was positively correlated to surface hydrophobicity but negatively to size and aggregation extent of MGLP. Interfacial pressure and dilatational elastic modulus implied that synergistic polyphenol interaction and pH shifting favored the interfacial adsorption and macromolecular association of MGLP, particularly for P-quercetin with the values reached to 19.9 ± 2.0 mN/m and 22.9 ± 1.2 mN/m, respectively. Emulsion stabilized by P-quercetin also maintained highest physical and oxidative stabilities regarding the lowest D [4,3] (3.78 ± 0.27 μm) and creaming index (8.38 ± 0.43 %), together with highest mono- (19.51 %) and polyunsaturated fatty acid content (29.39 %) during storage. Overall, chemical structure of polyphenols may be determining in fabricating MGLP-polyphenol complexes with improved emulsion stabilization efficiency.

The influence of α and α' subunits on SPI Pickering emulsions based on natural hybrid breeding varieties

In this study, food-grade protein nanoparticles (Wild-NPs, α-lack-NPs, α'-lack-NPs, and (α + α')-lack-NPs) were organized as emulsion stabilizers via thermal induction. The effects of α and α' subunits in soybean protein isolate (SPI) on Wild nanoparticle Pickering emulsion (Wild-NPPEs), α-lack nanoparticle Pickering emulsion (α-lack-NPPEs), α'-lack nanoparticle Pickering emulsion (α'-lack-NPPEs) and (α + α')-lack nanoparticle Pickering emulsion ((α + α')-lack-NPPEs) were investigated. The Pickering emulsion stabilization mechanism indicated that the α'-lack-NPs particle size, surface hydrophobicity, and contact angle were mostly comparatively large. Therefore, the absence of the α' subunit made the desorption of protein nanoparticles at the oil and water interface require higher energy. Through the hydrophobic interaction between molecules, the structure and properties of the emulsion were improved, showing good stability. The existence of α'-lack-NPPEs leads to the formation of a gel-like network in the emulsion, which increases the viscosity of the emulsion and makes the network structure of the emulsion more uniform and denser.

Aggregate Size Modulates the Oil/Water Interfacial Behavior of Myofibrillar Proteins: Toward the Thicker Interface Film and Disulfide Bond

Myofibrillar protein (MP) aggregate models have been established to elucidate the correlation between their aggregate sizes and interfacial properties. The interfacial layer thickness was measured by the polystyrene latex method and quartz crystal microbalance with dissipation measurement. Interfacial conformations were then characterized in situ (front-surface fluorescence spectroscopy) and ex situ (reactive sulfhydryl group and secondary structure measurement following MP displacement). The viscoelasticity of the interfacial film and its resistance to surfactant-induced competitive displacement were reflected by the dilatational rheology and dynamic interfacial tension with the bulk phase exchange. Finally, we compared the findings of competitive displacement before/after adding a sulfhydryl-blocking agent, N-ethylmaleimide, to highlight the role of S-S linkage on interfacial film formation and stability. We substantiated that the aggregate size of the MP governed their interfacial properties. Small-sized aggregates exhibited more ordered secondary structures on the oil-water interface, which was conducive to the adsorption ratio of the protein and the adsorption dynamics. Although larger aggregates lowered the diffusion rate during interfacial film formation, they allowed the thicker and more viscoelastic interfacial film to be constructed afterward through more disulfide bond formation, resulting in greater resistance to surfactant-induced competitive displacement.

A novel strategy for improving the stability of myofibrillar protein emulsions at low ionic strength using high-intensity ultrasound combined with non-enzymatic glycation

Poor emulsification of myofibrillar proteins (MPs) limits the production of meat protein emulsion-type products, and it is related to the myosin self-assembles in low-salt settings. The effect of high-intensity ultrasound (HIU) pretreatment combined with non-enzymatic glycation on MP-stabilized emulsions in low-salt settings was investigated in this study, and the potential mechanism was revealed. The results indicated that, compared to using either HIU or glycation treatment alone, HIU pretreatment in combination with glycation significantly improves the physical stability of emulsions while increasing the distribution uniformity and reducing the droplet particle size from 18.05 μm to 2.54 μm (P < 0.05). Correspondingly, the emulsion prepared using this approach exhibited a relatively high absolute zeta potential (-23.58 mV) and a high interfacial protein content (38.78 %) (P < 0.05), promoting molecular rearrangement and forming a continuous and stable interfacial layer. HIU pretreatment combined with glycation could offer reinforced electrostatic repulsion and steric hindrance to depolymerize self-assembled filamentous polymers, thus enhancing the stability of droplets. Additionally, the thermal sensitivity of the glycated MPs pretreated by HIU was remarkably reduced, thus improving the thermal stability of the corresponding emulsions.

Cryoprotective effect of soybean oil on surimi gels and the mechanism based on molecular dynamics simulation

The effect of soybean oil (SO) on freeze-thaw (F-T)-treated surimi was investigated and its related mechanism was revealed by molecular dynamics (MD) simulations. The results displayed that SO has a disrupting effect on the structure of fresh samples. However, in the F-T-treated samples, surimi gels supplemented with SO had a more uniform microstructure. Simultaneously, when SO was added from 0% to 7% in the F-T-treated samples, the gel strength increased from46.66 to 51.86 N · mm $$ 46.66\ \mathrm{to}\ 51.86\;\mathrm{N}\cdotp \mathrm{mm} $$ (p < .05), the physically bound water was increased from 92.90% to 94.15% (p < .05), and storage modulus was increased from 5939 to 6523 Pa. Triglycerides of SO generated hydrophobic interactions with myosin mainly in carbon chains. Computational results from MD simulations illustrated that the structure of myosin combined with triglycerides was more stable than that of myosin alone during temperature fluctuations (-20 to 4°C). During ice crystal growth, triglycerides absorbed on the myosin surface inhibited the growth of surrounding ice crystals and mitigated the ice crystal growth rate (from 7.54 to 5.99 cm/s). The addition of SO during the F-T treatments allowed myosin to be less negatively affected by ice crystal formation and temperature fluctuations and ultimately contributed to the formation of a more uniform network gel structure.

Molecular mechanisms affecting the stability of high internal phase emulsions of zein-soy isoflavone complexes fabricated with ultrasound-assisted dynamic high-pressure microfluidization

In this study, zein-soy isoflavone complex (ZSI) emulsifiers were fabricated using ultrasound-assisted dynamic high-pressure micro fluidization to stabilise highinternal phase pickering emulsions. Ultrasound-assisted dynamic high-pressure micro-fluidization enhanced surface hydrophobicity, zeta potential, and soy isoflavone binding capacity, while it decreased particle size, especially during ultrasound and subsequent microfluidization. The treated ZSI could produce small droplet clusters and gel-like structures, with excellent viscoelasticity, thixotropy and creaming stability owing to their neutral contact angles. Ultrasound and subsequent micro fluidization treatment of the ZSI complexes were highly effective in preventing droplet flocculation and coalescence after long-term storage or centrifugation due to their higher surface load, thicker multi-layer interfacial structure, and stronger electronic repulsion between the oil droplets. This study provides insights and extends our current knowledge of how non-thermal technology affects the interfacial distribution of plant based particles and the physical stability of emulsions.

Magnetic field-assisted cascade effects of improving the quality of gels-based meat products: A mechanism from myofibrillar protein gelation

Physics-assisted processing technologies have huge potential in the meat processing industry. By modeling two essential procedures (pickling and preheating) of gels-based meat products, this work investigated the cascade effects of a new physical technology (magnetic field) on the conformational structures and gel properties of myofibrillar proteins (MPs). Samples were subjected with four magnetic field (MF)-assisted treatments (group A, both processes without MF; group B, pickling without MF combining with preheating with 4.5 mT MF; group C, pickling with 3.0 mT MF combining with preheating without MF; group D, pickling with 3.0 mT MF combining with preheating with 4.5 mT MF). The result showed that MF-assisted treatments significantly improved water holding capacity (WHC) of MP gels compared with group A (46.9%), reaching the maximum value of 52.1% in group D.According to the low-field nuclear magnetic results, group D decreased the percentages of P₂₂ (6.97%) and increased the percentages of P₂₁ (93%), which showed that water molecules were more tightly bound to each other. Meanwhile, the unfolding of α-helix and the formation of random coil of MF-assisted treatments resulted in more exposure of internal groups, leading to the formation of a dense network. These findings would provide new insights to improve the quality of gels-based meat products via the MF.

Triumfetta cordifolia Gum as a Promising Bio-Ingredient to Stabilize Emulsions with Potentials in Cosmetics

The cosmetics industry is searching for efficient and sustainable substances capable of stabilizing emulsions or colloidal dispersions that are thermodynamically unstable because of their high surface energy. Therefore, surfactants are commonly used to stabilize the water/oil interface. However, the presence of a surfactant is not always sufficient to obtain stable emulsions on the one hand, and conventional surfactants are often subject to such controversies as their petroleum origin and environmental concerns on the other hand. As a consequence, among other challenges, it is obvious that research related to new-natural, biodegradable, biocompatible, available, competitive-surfactants are nowadays more intensive. This study aims to valorize a natural gum from Triumfetta cordifolia (T. cordifolia) as a sustainable emulsifier and stabilizer for oil-in-water (O/W) emulsions, and to evaluate how the nature of the fatty phase could affect this potential. To this end, O/W emulsions were prepared at room temperature using three different oils varying in composition, using a rotor-stator mixer. Resulting mixtures were characterized using optical microscopy, laser granulometry, rheology, pH and stability monitoring over time. The results demonstrated good potential for the gum as an emulsifying agent. T. cordifolia gum appears efficient even at very low concentrations (0.2% w/w) for the preparation and stabilization of the different O/W emulsions. The best results were observed for cocoglyceride oil due to its stronger effect of lowering interfacial tension (IFT) thus acting as a co-emulsifier. Therefore, overall results showed that T. cordifolia gum is undoubtedly a highly promising new bio-sourced and environmentally friendly emulsifier/stabilizer for many applications including cosmetics.

Regulation mechanism of curcumin-loaded oil on the emulsification and gelation properties of myofibrillar protein: Emphasizing the dose-response of curcumin

The regulation mechanism of curcumin (CUR) in the oil phase on the emulsification and gelation properties of myofibrillar protein (MP) was investigated. CUR enhanced the emulsifying activity index (EAI) of MP but decreased its turbiscan stability index (TSI) and surface hydrophobicity, which exacerbated oil droplet aggregation. Medium amounts (200 mg/L) of CUR changed the 3D network architectures of emulsion gels from lamellar to reticular, improving the gels' water-holding capacity (WHC), storage modulus, springiness, and cohesiveness. Besides, the LF-NMR revealed that CUR had limited effects on the mobility of immobilized and free water. The α-helix of MP in gels with medium amounts of CUR decreased from 51% to 45%, but the β-sheet increased from 23% to 27% compared to those without CUR. Overall, CUR has the potential to become a novel structural modifier in emulsified meat products due to its dose-response.

Contribution of process-induced molten-globule state formation in duck liver protein to the enhanced binding ability of (E,E)-2,4-heptadienal

BACKGROUND

Extracted proteins of alternative animal origin tend to present strong off-flavor perception due to physicochemical interactions of coextracted off-flavor compounds with proteins. To investigate the relationship between absorption behaviors of volatile aromas and the processes-induced variations in protein microstructures and molecular conformations, duck liver protein isolate (DLp) was subjected to heating (65/100 °C, 15 min) and ultra-high pressure (UHP, 100-500 MPa/10 min, 28 °C) treatments to obtain differential unfolded protein states.

RESULTS

Heat and UHP treatments induced the unfolding of DLp to varied degrees, as revealed by fluorescence spectroscopy, ultraviolet-visible absorption, circular dichroism spectra and surface hydrophobicity measurements. Two types of heating-denatured states with varied unfolding degrees were obtained, while UHP at both levels of 100/500 MPa caused partial unfolding of DLp and the presence of a molten-globule state, which significantly enhanced the binding affinity between DLp and (E,E)-2,4-heptadienal. In particular, significantly modified secondary structures of DLp were observed in heating-denatured samples. Excessive denaturing and unfolding degrees resulted in no significant changes in the absorption behavior of the volatile ligand, as characterized by observations of fluorescence quenching and analysis of headspace concentrations.

CONCLUSION

Defining process-induced conformational transition behavior of matrix proteins could be a promising strategy to regulate food flavor attributes and, particularly, to produce DLp coextracted with limited off-flavor components by modifying their interaction during extraction processes. © 2023 Society of Chemical Industry.

Effect of konjac oligo-glucomannan on emulsifying properties of myofibrillar protein

BACKGROUND

The high viscosity of konjac glumannan (KGM) limits its application in meat processing. In this work, the effects of konjac oligo-glucomannan (KOG), as a derivative of KGM, on the emulsifying properties of myofibrillar protein (MP) and the related mechanism were investigated.

RESULTS

It was found that the addition of KOG had no significant effect on the secondary structure of MP, but altered the tertiary conformation of MP, resulting in exposure of tyrosine residues to polar microenvironments and decreased intrinsic fluorescence intensity. In addition, the addition of KOG increased the emulsifying activity of MP, resulting in decreased particle size and improved physical stability of the emulsion. The emulsifying activity of MP reached the maximum value when 1.0 wt% KOG was added. Moreover, the interfacial tension and interfacially adsorbed protein content of MP/KOG emulsions decreased with the increase in KOG concentration.

CONCLUSION

These findings demonstrated that KOG mainly interacted with MP and changed the amphipathy of the KOG-MP at the oil-water interface, forming a stable interface film to improve the emulsifying properties of MP. © 2023 Society of Chemical Industry.

Gel-type emulsified muscle products: Mechanisms, affecting factors, and applications

The gel-type emulsified muscle products improve fatty acid composition, maintain the oxidative stability, and achieve a better sensory acceptability. This review emphasizes the stabilization mechanisms of these emulsified muscle products. In particular, factors associated with the stability of the emulsified muscle systems are outlined, including the processing conditions (pH and heating), lipids, and emulsifiers. Besides, some novel systems are further introduced, including the Pickering emulsions and organogels, due to their great potential in stabilizing emulsified gels. Moreover, the promising prospects of emulsion muscle products such as improved gel properties, oxidative stability, freeze-thaw stability, fat replacement, and nutraceutical encapsulation were elaborated. This review comprehensively illustrates the considerations on developing gel-type emulsified products and provides inspiration for the rational design of emulsified muscle formulations with both oxidatively stable and organoleptically acceptable performance.