pH-dependent characteristics of gel-like emulsion stabilized by threadfin bream sarcoplasmic proteins

Enhancing gel behavior of yellow croaker surimi by fruit extracts: Physicochemical properties and molecular mechanism

The aim of this study was to investigate the effects of grape seed extract (GSE), acerola cherry extract (ACE), and blueberry extract (BBE) on the physicochemical properties and structure of the yellow croaker surimi gel. In addition, molecular docking and molecular dynamics (MD) simulation were utilized to study the binding mechanism of yellow croaker's fibrillin and fruit extracts. Surimi gel with 1.5% GSE, ACE, and BBE had the highest water holding capacity, hardness, chewability, cohesion, breaking force, breaking distance, gel strength, and densest 3D network structure, according to the experiment's findings. Nevertheless, the cross-linking of proteins in surimi was blocked with the further increase of fruit extract (1.5%-2.0%), and the existing network of surimi was weakened or even destroyed. Three fruit extracts had little effect on the secondary structure of the surimi gel. Besides, hydrophobic and disulfide bonds are the main chemical bonds of croaker surimi. Molecular docking showed that B-type procyanidine (BP) interacted with ASN-183, SER-571, ASP-525, ARG-350, LYS-188, GLU-349, CYS-353, and other active amino acids in croaker protein. Moreover, it can form strong hydrogen bond interaction with ASN-183, SER-571, ASP-525, and ARG-350 at the active sites of protein. The BP-Larimichthys crocea protein system's MD simulation was carried out, and calculations for the simulation's root mean square deviation, root mean square fluctuation, radius of gyration, solvent accessible surface area, and hydrogen bonds were made. It was found that these indices can demonstrate that the BP binding contributes to the stability of the yellow croaker structure.

Effects of heating rates on the self-assembly behavior and gelling properties of beef myosin

BACKGROUND

Myosin is the most important component of myofibrillar protein, with excellent gelling properties. To date, heating treatment remains the mainstream method for forming gel in meat products, and it has the most extensive application in the field of meat industry. However, at present, there are few reports on the effects of heating rates on myosin self-assembly and aggregation behavior during heating treatment.

RESULTS

The present study aimed to investigate the effects of different heating rates (1, 2, 3 and 5 °C min^-1 ) on the self-assembly behavior, physicochemical, structural and gelling properties of myosin. At the lowest heating rate of 1 °C min^-1 , the myosin gel had a dense microstructure, the highest elastic modulus (G') and water holding capacity compared to higher heating rates (2, 3 and 5 °C min^-1 ). At higher temperatures (40, 45 °C), the surface hydrophobicity, turbidity, particle size distribution and self-assembly behavior of myosin in pre-gelling solutions showed that myosin had sufficient time to denature, underwent full structure unfolding before aggregation at the heating rate of 1°C min^-1 , and formed regular and homogeneous spherical aggregates. Therefore, the myosin gel also had a better three-dimensional network.

CONCLUSION

The heating rates had an important effect on the quality of myosin gels, and had theoretical implications for improving the quality of meat gel products. © 2023 Society of Chemical Industry.

Effect of sarcoplasmic proteins oxidation on the gel properties of myofibrillar proteins from pork muscles

This study investigated the influence of sarcoplasmic proteins (SPs) treated by the oxidation system (0.1 mmol/L FeCl₃ , 0.1 mmol/L ascorbic acid, and 0, 1, 5, 10 mmol/L H₂ O₂ ) on the properties of pork myofibrillar proteins (MPs) gel. After oxidation treatment, the SPs showed an increased in carbonyl content and a decreased in total sulfhydryl content, coupled with the cross-linking of protein components by disulfide bonds and covalent bonds. The MPs gel with SPs oxidized at 1 mmol/L H₂ O₂ exhibited the maximal strength while the minimal water holding capacity (WHC). The WHC of MPs gel was significantly decreased with increasing SPs oxidation, leading to the increase of free water and the decrease of immobilized water in the gel system. The microstructures of MPs gels with moderately (1 mmol/L H₂ O₂ ) oxidized SPs showed a more compact and smaller pore gel network than MPs alone, suggesting adding oxidized SPs can expel water trapped in the gel. Furthermore, the environmental polarity of aliphatic C-H groups increased with SPs oxidation.

Physicochemical and emulsifying properties of mussel water-soluble proteins as affected by lecithin concentration

The effects of lecithin addition at different concentrations (0-2.0%) on the physicochemical and emulsifying properties of mussel water-soluble proteins (MWP) were investigated. In solution system, low lecithin concentration (0.5%-1.0%) induced the aggregation and increased turbidity of composite particles. Lecithin addition caused changes in secondary structure and induced partial unfolding of MWP. Hydrophobic interactions between MWP and lecithin may contribute to the exposure of chromophores and hydrophobic groups of MWP. The interfacial tension decreased with lecithin addition. However, at a high lecithin concentration (1.5%-2.0%), the degree of aggregation and state of unfolding alleviated due to competitive adsorption. In emulsion system, with the low concentration of lecithin addition (0.5%-1.0%), droplet size and surface charge of emulsion decreased. The emulsion activity index, emulsion stability index, percentage of adsorbed protein increased. Both creaming stability and viscoelastic properties improved. At an intermediate lecithin concentration (1.0%), the emulsion showed the highest physical stability, while further addition of lecithin caused a slight deterioration in emulsifying properties. Overall, these results indicated the possibility that the lecithin-MWP mixed emulsifiers can be used to obtain emulsions with desirable properties.

Enzymatically Treated Spent Cellulose Sausage Casings as an Ingredient in Beef Emulsion Systems

The objective of this research was to incorporate an ingredient obtained from spent cellulose casings in beef emulsion modeling systems. The test ingredient (residual sausage casing, RSC) was procured from cellulose sausage casings following thermal processing of the sausages. The casings were cleaned of contaminants before a combination of enzymatic hydrolysis and high-speed homogenization was conducted in an effort to improve the functional attributes of the cellulose casing residue (i.e. recycling/upcycling of the spent casings). The beef emulsion modeling systems used in this study consisted of 57.30% beef, 20% water, 15% olive oil, 6% of the combination of RSC and an all-purpose binder, 1.45% NaCl, 0.40% sodium tri-polyphosphate, 0.15% sodium nitrite cure, and 0.0035% sodium erythorbate. The overlying goal here was to test the ability of the RSC ingredient for partial or full replacement of binder ingredients in a beef emulsion system. Therefore, the beef emulsion model systems were prepared with five different levels of the RSC ingredient as a substitution to an all-purpose binder ingredient (0% RSC, 25% RSC, 50% RSC, 75% RSC, and 100% RSC). This study was independently replicated in its entirety three times in a completely randomized design and data were analyzed using a generalized linear mixed statistical model. Emulsion samples were tested for proximate composition, cooking loss, emulsion stability, texture profile analysis, and instrumental color. Overall, technological properties and emulsion stability were lost as the level of the RSC ingredient increased, but low inclusion levels of the RSC ingredient (25% RSC) may help maintain acceptable levels of yield and emulsion stability, while improving the sustainability of the sausage production system.

Modifying the Physicochemical and Functional Properties of Water-soluble Protein from Mussels by High-pressure Homogenization Treatment

This study investigated the changes in physicochemical and functional properties of water-soluble protein from mussels (MWP) induced by high-pressure homogenization (HPH). The results indicated that HPH treatment unfolded or disrupted the initial structure of MWP, exposing free sulfhydryl groups and buried hydrophobic groups. As the homogenization pressure increased, the aggregation of MWP particles gradually decreased. Moreover, protein solubility and dispersion stability increased in aqueous solution. Foaming and emulsifying properties were also improved. HPH treatment has proven to be an effective technique for enhancing the functional properties of shellfish protein, and 120 MPa was the optimum homogenization pressure to modify MWP.

Interfacial and enhanced emulsifying behavior of phosphorylated ovalbumin

Improvement of emulsifying properties by phosphorylation could have a wide potential application in food industry. In this study, ovalbumin (OVA) was phosphorylated under wet-heating in the presence of sodium tripolyphosphate. Phosphorylated OVA (P-OVA) with low, middle, high phosphorus content were obtained with reaction time increased. Their enhanced emulsification capacity and the mechanism were investigated. Compared with native OVA (N-OVA), the emulsifying activity and stability of P-OVA were increased by 26% and 109% (P < 0.05), respectively. The structure studies (Fourier transform infrared spectroscopy, circular dichroism spectra, scanning electron microscope) demonstrated that introduction of phosphate groups to OVA increased the molecular flexibility of P-OVA. The absolute values of surface zeta-potential and surface hydrophobicity were increased as the phosphorus content increased, which indicated that the phosphate group inhibited protein aggregation. And it caused a large amount absorption of protein on the surface of the oil droplets, which ultimately improved the emulsion stability. Both particle size and microscopic results of emulsion showed that the particle size of OVA reduced as the degree of phosphorylation increased, which improved the emulsifying ability.

Chemical and Functional Characterization of Sarcoplasmic Proteins from Giant Squid (Dosidicus gigas) Mantle

Modification of pH and NaCl concentration changed the physicochemical properties of sarcoplasmic proteins (SP) from jumbo squid mantle and consequently their functional properties. Better results of emulsifying activity index (EAI) and foam capacity (FC) were exhibited at pH 11 in NaCl absence due to higher solubility. But better emulsifying stability index (ESI) was obtained at pH 11 in 0.5 M NaCl, while, foaming stability (FS) was better at pH near to isoelectric point (pI). These results suggest that SP from jumbo squid may be a promising ingredient, whose functional properties can be manipulated by changing pH and NaCl concentration.