Ultrasound treated fish myofibrillar protein: Physicochemical properties and its stabilizing effect on shrimp oil-in-water emulsion

Bigels based on myofibrillar protein hydrogel and beeswax oleogel: Micromorphology, mechanical property, and rheological properties

This study developed a bigel system comprising of myofibrillar protein hydrogel (H-MP) and beeswax oleogel. The effects of hydrogel to oleogel ratios and the addition of Zanthoxylum essential oil (ZEO) were systematically investigated. Mechanical properties revealed that an increased proportion of oleogel resulted in enhanced gel strength, bigel BW-90 exhibiting the highest strength. As a texture modifier, ZEO significantly influenced the mechanical properties of the bigels. Micromorphology characterization indicated a phase transition from oleogel-in-hydrogel (O/H) to hydrogel-in-oleogel (H/O) as the oleogel proportion increased, leading to a shift from a porous structure to a more uniform and denser one. XRD results demonstrated that the amorphous nature of the oleogel dominated the crystalline structure of the bigel system. Rheological analysis confirmed that the bigels exhibited strong viscoelastic behavior and frequency resistance, with H-MP enhancing the thermal stability of the bigels. The high storage modulus (G') values suggested potential applications of these bigels in shaped food products. This study thoroughly explored the potential applications of the bigel system as a fat substitute and 3D printing material, providing a theoretical foundation and technical support for its use in food industry.

(E,E)-2,4-decadienal improved the stability of gelatin emulsion manufactured by low-energy stirring emulsification

The study investigated the impact of varying concentrations of (E,E)-2,4-dodecenal (DDE; 0, 9, 27, 54, and 81 μg/mL) on the stability of gelatin emulsions prepared via a low-energy stirring emulsification method, which relies solely on simple mechanical stirring. As the concentration of DDE increased, the particle size, emulsifying activity index, emulsion stability index, and viscosity of emulsions first increased significantly (P < 0.05) and then decreased significantly (P < 0.05), indicating that the emulsion stability first improved and then decreased. The highest emulsion stability was observed at a DDE concentration of 27 μg/mL, as evidenced by the highest adsorbed protein content (84.78 %) and the maximum absolute zeta potential value (14.46 mV). These findings suggested that DDE, in combination with low-energy stirring emulsification, improved the stability of gelatin emulsions. The results of protein structure indicated that DDE enhanced the depolymerization of gelatin by disrupting hydrophobic interactions within gelatin aggregates, leading to the exposure of hydrophobic groups on the protein surface. This exposure enhanced the adsorption of gelatin at the oil-water interface, thereby improving the emulsion stability through increased steric hindrance at the interface. Furthermore, DDE reduced the interfacial tension of soybean oil, contributing to further stabilization of the interface.

Ultrasound-induced food protein-stabilized emulsions: Exploring the governing principles from the protein structural perspective

Consumers' growing demand for healthy and natural foods has led to a preference for products with fewer additives. However, the low emulsifying properties of natural proteins often necessitate the addition of emulsifiers in food formulations. Consequently, enhancing the emulsifying properties of proteins through various modification methods is crucial to meet modern consumer demands for natural food products. High-intensity ultrasound offers a green, efficient processing technology that significantly improves the emulsifying properties of proteins. This study explores how ultrasound treatment enhances the stability of protein-based emulsions by modifying protein structures. While ultrasonic treatment does not significantly affect the primary structure of proteins, it influences the secondary, tertiary, and quaternary structures depending on the type of protein, ultrasound parameters (type, intensity, and time), and treatment conditions. The results suggest that ultrasound treatment reduces α-helix content, decreases protein particle size, and increases β-sheet content, surface hydrophobicity, free sulfhydryl groups, and zeta potential, leading to a more stable protein-based emulsion. The reduced particle size and increased flexibility of proteins induced by ultrasound enable more rapid protein adsorption at the oil-water interface, resulting in smaller emulsion droplets. This contributes to the emulsion's improved stability during storage. Future research should focus on the large-scale application of ultrasonic treatment for protein modification to produce high-quality, natural foods that meet the evolving needs of consumers.

Ultrasound assisted complexation of soybean peptide aggregates and soluble soybean polysaccharide: pH optimization, structure characterization, and emulsifying behavior

This study aims to enhance the emulsifying properties of soybean peptide aggregates (SPA) by preparing SPA-soluble soybean polysaccharide (SSPS) composite particles at the assistance of ultrasound technique. The optimal pH for SPA and SSPS complexation was determined by measuring the charge and particle size of the composites. The effects of ultrasound power and duration on the physicochemical properties of the composite particles were assessed through measurements of particle size, zeta potential, contact angle, FTIR, and SEM. The influence of ultrasound duration on the emulsifying properties of the composite particles was evaluated by particle size, zeta potential, microstructure, rheology, and in vitro digestibility. The optimal pH for SPA and SSPS complexation was determined to be 4.0. Zeta potential and FTIR analyses indicated that ultrasound enhanced the electrostatic interactions and hydrogen bonding between SPA and SSPS. Emulsions stabilized with ultrasonicated composite particles exhibited reduced particle sizes, increased viscosity, improved viscoelastic properties, and better in vitro digestibility. The results suggest that moderate ultrasound treatment can strengthen the interactions between SPA and SSPS, thereby enhancing their emulsifying properties. This study offers valuable insights into enhancing the emulsifying performance of highly hydrophobic protein particles.

Cold plasma technology: A cutting-edge approach for enhancing shrimp preservation

Cold plasma (CP) is an emerging technology employed to safeguard highly perishable food items, particularly aquatic products such as shrimp. Due to its significant amount of moisture, superior protein composition that contains important amino acids, and unsaturated fatty acid content, shrimp are susceptible to microbial deterioration and overall alterations in their physical and chemical characteristics. Such spoilage not only diminishes the nutritional value of shrimp but also has the potential to generate harmful substances, rendering it unsuitable for consumption. Recent observations have indicated a growing market demand for shrimp that maintains its quality and has a prolonged shelf life. Furthermore, there is a significant emphasis on the production of food items that undergo minimal processing or nonthermal preservation methods. Extensive documentation exists regarding the efficacy of CP technology in eliminating microorganisms from shrimp without inducing resistance or activating enzymes that contribute to shrimp spoilage. Therefore, CP can be mentioned as a slight processing interference to preserve shrimp quality. This chapter primarily explores the principles and methods of CP technology, as well as its impact on melanosis, physicochemical changes, microbial and sensory properties, and the preservation of shrimp quality.

Engineering of protein glutaminase for highly efficient modification of fish myofibrillar protein through structure-based and computational-aided strategy

Protein glutaminase (PG; EC 3.5.1.44) is a class of food-grade enzyme with the potential to significantly improve protein functionality. However, its low catalytic activity and stability greatly hindered industrial application. In this study, we employed structural-based engineering and computational-aided design strategies to target the engineering of protein glutaminase PG5, which led to the development of a combinatorial mutant, MT8, exhibiting a specific activity of 31.1 U/mg and a half-life of 216.2 min at 55 °C. The results indicated that the flexible region in MT8 shifted from the C-terminus to the N-terminus, with increased N-terminal flexibility positively correlating with its catalytic activity. Additionally, MT8 notably boosted fish myofibrillar proteins (MPs) solubility under the absence of NaCl conditions and enhanced their foaming and emulsifying properties. Key residues like Asp31, Ser72, Asn121, Asp471, and Glu485 were crucial for maintaining PG5-myosin interaction, with Ser72 and Asn121 making significant energy contributions.

The influence of pH-ultrasonic-induced myofibrillar protein conformation of Penaeus vannamei (Litopenaeus vannamei) on emulsification and digestion characteristics of fish oil oleogel-based emulsions

pH-induced and ultrasound treatment can both adjust spatial conformation to improve the interfacial stability, and fish oil oleogel could be used to enhance oil binding capacity. The relationship between stabilization mechanism and lipid digestion was revealed, considering the protein conformation and interfacial characteristics. The results showed that pH-ultrasonic-induced myofibrillar proteins (MPs) at pH 7.0 had higher interfacial adsorption capacity and surface hydrophobicity as well as more stable secondary structures, which lowered the particle size and enhanced the interfacial stability. In the stomach, the particle size increased along with the decrease in electrostatic repulsion, and β-sheets significantly increased, which promoted aggregation and flocculation. In the small intestine, the reduction of β-sheets favored the interfacial replacement and facilitated the lipid digestion. Therefore, pH-ultrasonic-modified method improved the structure and function of MPs, facilitated the interfacial stability and intestinal digestion.

Effect of γ-oryzanol/β-sitosterol-based oleogels on the physicochemical and gel properties of Nemipterus virgatus myofibrillar protein

BACKGROUND

The effect of oleogels prepared with peanut oil and different concentrations of γ-oryzanol and β-sitosterol mixture (γ/β; 20, 40, 60, 80 and 100 g kg-1) on the physicochemical and gel properties of myofibrillar protein (MP) was investigated.

RESULTS

The solubility and average particle size of MP first decreased and then increased with increasing γ/β concentration. Peanut oil or oleogels could induce the exposure of hydrophobic amino acids and the unfolding of MP, thus significantly increasing the surface hydrophobicity, sulfhydryl content and absolute value of zeta potential, which reached maximum values when the γ/β concentration was 60 g kg-1 (P < 0.05). The addition of peanut oil decreased the gel strength and water holding capacity of MP gel. However, oleogels prepared with 60 g kg-1 γ/β could significantly increase the hydrophobic interactions and disulfide bond content of MP gel (P < 0.05), which promoted the crosslinking and aggregation of MP, enhancing the gel properties. Peanut oil had no significant influence on the secondary structure of MP, while oleogels promoted the transition of MP conformation from α-helix to β-sheet structure. The results of light microscopy and confocal laser scanning microscopy indicated that oleogels prepared with 60 g kg-1 γ/β filled in the pores of MP gel network to form denser and more uniform structure.

CONCLUSION

Oleogels prepared with 60 g kg-1 γ/β could effectively improve the quality of MP gel and have promising application prospects in surimi products. © 2024 Society of Chemical Industry.

Effects of ultrasonic treatment on the structure and functional characteristics of myofibrillar proteins from black soldier fly

In the process of utilizing black soldier fly larvae (BSFL) lipids to develop biodiesel, many by-products will be produced, especially the underutilized protein components. These proteins can be recycled through appropriate treatment and technology, such as the preparation of feed, biofertilizers or other kinds of bio-products, so as to achieve the efficient use of resources and reduce the generation of waste. Myofibrillar protein (MP), as the most important component of protein, is highly susceptible to environmental influences, leading to oxidation and deterioration, which ultimately affects the overall performance of the protein and product quality. For it to be high-quality and fully exploited, in this study, black soldier fly myofibrillar protein (BMP) was extracted and primarily subjected to ultrasonic treatment to investigate the impact of varying ultrasonic powers (300, 500, 700, 900 W) on the structure and functional properties of BMP. The results indicated that as ultrasonic power increased, the sulfhydryl content and turbidity of BMP decreased, leading to a notable improvement in the stability of the protein emulsion system. SEM images corroborated the changes in the microstructure of BMP. Moreover, the enhancement of ultrasound power induced modifications in the intrinsic fluorescence spectra and FTIR spectra of BMP. Additionally, ultrasonic treatment resulted in an increase in carbonyl content and emulsifying activity of BMP, with both peaking at 500 W. It was noteworthy that BMP treated with ultrasound exhibited stronger digestibility compared to the untreated. In summary, 500 W was determined as the optimal ultrasound parameter for this study. Overall, ultrasound modification of insect MPs emerges as a dependable technique capable of altering the structure and functionality of BMP.

Functional and Mechanistic Dissection of Protein Glutaminase PG3 and Its Rational Engineering for Enhanced Modification of Myofibrillar Proteins

Protein glutaminases (PG; EC = 3.5.1.44) are enzymes known for enhancing protein functionality. In this study, we cloned and expressed the gene chryb3 encoding protein glutaminase PG3, exhibiting 39.4 U/mg specific activity. Mature-PG3 featured a substrate channel surrounded by aromatic and hydrophobic amino acids at positions 38-45 and 78-84, with Val81 playing a pivotal role in substrate affinity. The dynamic opening and closing motions between Gly65, Thr66, and Cys164 at the catalytic cleft greatly influence substrate binding and product release. Redesigning catalytic pocket and cocatalytic region produced combinatorial mutant MT6 showing a 2.69-fold increase in specific activity and a 2.99-fold increase at t65 °C1/2. Furthermore, MT6 boosted fish myofibrillar protein (MP) solubility without NaCl. Key residues such as Thr3, Asn54, Val81, Tyr82, Asn107, and Ser108 were vital for PG3-myosin interaction, particularly Asn54 and Asn107. This study sheds light on the catalytic mechanism of PG3 and guided its rational engineering and utilization in low-salt fish MP product production.

Advances of protein-based emulsion gels as fat analogues: Systematic classification, formation mechanism, and food application

Fat plays a pivotal role in the appearance, flavor, texture, and palatability of food. However, excessive fat consumption poses a significant risk for chronic ailments such as obesity, hypercholesterolemia, and cardiovascular disease. Therefore, the development of green, healthy, and stable protein-based emulsion gel as an alternative to traditional fats represents a novel approach to designing low-fat food. This paper reviews the emulsification behavior of proteins from different sources to gain a comprehensive understanding of their potential in the development of emulsion gels with fat-analog properties. It further investigates the emulsifying potential of protein combined with diverse substances. Then, the mechanisms of protein-stabilized emulsion gels with fat-analog properties are discussed, mainly involving single proteins, proteins-polysaccharides, as well as proteins-polyphenols. Moreover, the potential applications of protein emulsion gels as fat analogues in the food industry are also encompassed. By combining natural proteins with other components such as polysaccharides, polyphenols, or biopolymers, it is possible to enhance the stability of the emulsion gels and improve its fat-analog texture properties. In addition to their advantages in protecting oil oxidation, limiting hydrogenated oil intake, and delivering bioactive substances, protein-based emulsion gels have potential in food 3D printing and the development of specialty fats for plant-based meat.

Sonication as a potential tool in the formation of protein-based stable emulsion - Concise review

Emulsion systems are extensively used in the food processing sector and the use of natural emulsifiers like proteins for stabilizing emulsion has been in demand from consumers due to increased awareness about the consumption of healthy food. Numerous methods are available for the preparation of emulsion, but ultrasound got more attention among common methods owing to its economical and environment-friendly characteristics. The physical effects caused by to bursting of the cavity bubble, result in reduced droplet size, thus forming an emulsion with appreciable stability. Ultrasound ameliorates the emulsifying characteristics of natural emulsifiers like protein and improves the storage stability of the emulsion by positively boosting the rheological, emulsifying characteristics, improving zeta potential, and reducing average droplet size. The stability of protein-based emulsion is affected by environmental stresses hence conjugate of protein with polysaccharide showed good emulsifying characteristics. However, the data on the effect of ultrasound parameters on emulsifier properties is lacking and there is a need to develop a sonication device that can carry out large-scale emulsification operation. The review covers the principles and mechanisms of ultrasound-assisted formation of protein-based and protein-based conjugate emulsions. Further, the effect of ultrasound on various characteristics of protein-based emulsion is also explored. This review will provide concise data to the researchers to extend their experiments in the area of ultrasound emulsification which will help in commercializing the technology at the industrial scale.

The Cryoprotective Effect of an Antifreeze Collagen Peptide Complex Obtained by Enzymatic Glycosylation on Tilapia

Antifreeze peptides have become effective antifreeze agents for frozen products, but their low quantity of active ingredients and high cost limit large-scale application. This study used the glycosylation of fish collagen peptides with glucosamine hydrochloride catalyzed by transglutaminase to obtain a transglutaminase-catalyzed glycosylation product (TGP) and investigate its antifreeze effect on tilapia. Compared with the blank group, the freshness (pH value of 6.31, TVB-N value of 21.7 mg/100 g, whiteness of 46.28), textural properties (especially hardness and elasticity), and rheological properties of the TGP groups were significantly improved. In addition, the protein structures of the samples were investigated using UV absorption and fluorescence spectroscopy. The results showed that the tertiary structure of the TGP groups changed to form a dense polymer. Therefore, this approach can reduce the denaturation and decomposition of muscle fibers and proteins in fish meat more effectively and has a better protective effect on muscle structure and protein aggregation, improving the stability of fish meat. This study reveals an innovative method for generating antifreeze peptides by enzymatic glycosylation, and glycosylated fish collagen peptide products can be used as new and effective green antifreeze agents in frozen foods.

Storage stability of Asian seabass oil-in-water Pickering emulsion packed in pouches made from electrospun and solvent casted bilayer films from poly lactic acid/chitosan-gelatin blend containing epigallocatechin gallate

Bilayer pouches were fabricated with chitosan (CS)-fish gelatin (FG) mixture containing epigallocatechin gallate (EGCG) deposited over the poly lactic acid (PLA) film through solvent casting and electrospinning techniques. Pickering emulsions (PE) of Asian seabass depot fat oil stabilized by zein colloidal particles were packed in bilayer pouches and stored at 28 ± 2 °C. The PE packed in pouch containing EGCG had higher emulsion and oxidative stability after 30 days of storage as witnessed by the smaller droplet size and lower values of thiobarbituric acid reactive substances, peroxide, conjugated diene and volatile compounds in comparison with control (PE packed in monolayer PLA pouch) (P < 0.05). EGCG incorporated pouch retained more linoleic acid (C18:2 n-6) and linolenic acid (C18:3 n-9) in emulsion than PLA pouch. Therefore, pouch from bilayer PLA/CS-FG films comprising EGCG could serve as active packaging and extended the shelf life of Pickering emulsion.

Ultrasonic treatment treated sea bass myofibrillar proteins in low-salt solution: Emphasizing the changes on conformation structure, oxidation sites, and emulsifying properties

The physiochemical properties, structure characteristics, oxidation, and emulsifying properties of myofibrillar proteins (MPs) in low salt solution after treated by the ultrasound were investigated. The solubility, mean diameters, sulfhydryl content, and carbonyl contents of MPs after ultrasonic treatment increased, while the turbidity decreased. The surface hydrophobicity of MPs with 200 W-600 W treatment increased, but decreased at 800 W treatment. The circular dichroism analysis revealed that α-helix content increased, while β-sheet and random coil content decreased after ultrasonic treatment. Fluorescence spectroscopy indicated the fluorescence intensities of MPs were increased after ultrasonic treatment. SDS-PAGE results showed more protein polymers due to myosin heavy chain (MHC) aggregation via disulfide bonds. Based on LC-MS/MS result, the myosin heavy chain was susceptible to oxidation, with monooxidation being the main oxidative modification. Finally, the emulsions stabilized by ultrasonically treated MPs, especially those treated at 800 W, exhibited decreased particle size, improved uniformity, and enhanced stability.

Improvement of the emulsifying properties of Zanthoxylum seed protein by ultrasonic modification

The influence of ultrasonic treatment (100-500 W, 30 min) on the molecular structures and emulsifying properties of Zanthoxylum seed protein (ZSP) was explored for the first time in this work. Research results indicated that the all ultrasonic treatments at different power levels decreased the particle size but increased the surface charge of ZSP. In addition, the ultrasonic treatments induced the structural unfolding of the ZAP, as indicated by the increase in α-helix, ultraviolet-visible absorbance, surface hydrophobicity and the amount of surface free sulfhydryl groups, as well as the decrease in β-sheet and intrinsic fluorescence intensity. As a result, the significantly (p < 0.05) increased emulsifying activity index (EAI) and emulsion stability index (ESI) of ZSP were observed after ultrasonic treatment. In addition, the emulsion prepared by ultrasonically treated ZSP exhibited the smaller and more uniform droplets with significantly improved stability against environmental stress (temperature, salt concentration, pH), creaming and oxidation due to the increased ratio of interfacially adsorbed ZSP. Furthermore, ultrasonic treatment at 400 W was found to be the optimum condition for modification. These findings will provide a theoretical foundation for the utilization of ultrasound in enhancing the emulsifying properties of ZSP and promoting its application in the field of food processing.