Ultrasound-assisted immersion freezing reduces the structure and gel property deterioration of myofibrillar protein from chicken breast

Solubilization strategy of myofibrillar proteins in low-ionic media (prototype soup): The effect of high-intensity ultrasound combined with non-covalent or covalent modification of polyphenols on myosin molecular assembly

This study investigated the effect of (-)-Epigallocatechin-3-gallate (EGCG) non-covalent/covalent grafting onto myofibrillar protein (MP) by high-intensity ultrasound (HIU) on its water-solubility and filament forming behavior. The results showed that the introduction of EGCG, especially in the case of covalent grafting, could inhibit the molecular assembly of myosin and improve the MP water solubility from 2.7% to 53.1% (P < 0.05). The HIU pretreatment provided more opportunities for EGCG grafting onto the ultrasound-treated protein (UMP) by disrupting the filamentous polymerization of myosin and thus further facilitated MP dissolution. Additionally, compared with the UMP-EGCG non-covalent complexes, the covalent complexes with a yellow appearance exhibited a higher absolute zeta potential (35.9 mV) and a lower particle size (53.7 μm) (P < 0.05). Overall, the combination of HIU pretreatment and EGCG covalent modification may provide a promising method for improving the solubility and processing properties of MP in low ionic media (prototype soup).

Effect of soluble dietary fiber on soy protein isolate emulsion gel properties, stability and delivery of vitamin D3

Emulsion gels with denser network microstructure and stronger mechanical properties have attracted increasing attentions for delivering lipophilic compounds. In this study, the effect of three distinct soluble dietary fiber (inulin (IN), resistant dextrin (RD) and stachyose (ST)) on the rheological, mechanical and microstructural properties of soy protein isolate (SPI) emulsion gel were firstly investigated. Compared with RD and IN, ST significantly accelerated water holding capacity and thermal stability, which exhibited more compact microstructure and more uniform emulsified oil droplets. Subsequently, the stability and bioavailability of vitamin D3 (VD3) in different delivery systems (medium chain triglycerides (MCT) embedding, SPI-ST emulsion embedding, SPI emulsion gel embedding and SPI-ST emulsion gel embedding) were continue evaluated. In vitro simulated digestion experiment demonstrated that the bioaccessibility of encapsulated VD3 in SPI-ST emulsion gel (69.95 %) was much higher than that of free embedding (48.99 %). In vivo pharmacokinetic experiment revealed that the bioavailability of VD3 was significantly enhanced in SPI-ST gel (p < 0.05), with the AUC0-24h value of 25-OH VD3 (the main circulating form of VD3) were 1.34-fold, 1.23-fold higher than that of free embedding, MCT embedding, respectively. These findings provide a possible approach for the development of high protein/fiber functional foods containing enhanced hydrophobic bioactives.

Investigating the rheological properties and 3D printability of tomato-starch paste with different levels of xanthan gum

Tomato is an inexpensive vegetable with high nutritional value，but it does not have the suitable self-supporting ability for 3D printing. Xanthan gum (XG) is a common thickener that may improve 3D printability of tomatoes paste. This study evaluated the printability of tomato-starch paste (TSP) by examining its rheological and textural properties and microstructure of 3D samples. The rheological results showed that apparent viscosity, recovery rate, storage modulus, loss modulus, initial and average rheological forces, and shear stress increased significantly (P < 0.05) with increase of XG levels in tomato-starch paste. The low-field NMR results showed that T21 and T22 of the TSP decreased with increase of XG levels (P < 0.05). With increase of XG levels, a dense network structure in the TSP was formed as observed in the microstructural images. The TSP with 5 g/kg XG had the highest printing accuracy, and the textural property showed that the addition of 5 g/kg of XG significantly improved the hardness, elasticity, and chewability of TSP (P < 0.05). Overall, with increase of XG levels the fluidity of the pseudoplastic gel formed by the tomato-starch system and increased the density of the structure, resulting in improved extrudability, shape stability, and self-supporting property.

Uncovering the rheological properties basis for freeze drying treatment-induced improvement in the solubility of myofibrillar proteins

Myofibrillar proteins (MPs) are an important nutritional supplement and have great significance in sports training and rehabilitation therapy. Currently, MPs preservation is still disputed since they are vulnerable to degradation, polymerization, and denaturation. Freeze-drying is an emerging technology for protein preservation, its effects on the functionality of MPs from different sources have not yet been thoroughly studied. This study aims to evaluate the performance differences of freeze-drying in maintaining the functional characteristics of MPs from fish and mammalian sources, providing valuable insights for the processing and preservation of MPs, and providing nutritional support for nursing and rehabilitation. The results showed that freeze-drying was an efficient method for protein preservation, and the effects of freeze-drying on both fish and mammalian sources MPs were significant (p < 0.05) consistent. Specifically, whether before and after freeze-drying, the solubility of fish MPs (FMPs) was significant (p < 0.05) lower than that of mammalian MPs, while the foaming and emulsifying properties were significant (p < 0.05) higher than those of beef and sheep MPs (BMPs and SMPs, respectively). Furthermore, the most efficient protein concentration for freeze-drying was 10 mg/mL, and with this concentration, the gel strengths of BMPs and SMPs showed an insignificant difference (p > 0.05) after freeze-drying.

Injection of l-arginine or l-lysine before freezing delays the emulsifying and gelling properties deterioration of myofibrillar proteins of frozen porcine Longissimus lumborum muscle

This study aimed to investigate the effects of injecting l-arginine and l-lysine solution before freezing and after thawing on the emulsifying and gelling properties of myofibrillar proteins (MPs) of frozen porcine longissimus dorsi. The results showed that the pre-freezing injections were more effective in alleviating the decrease in emulsifying properties of MPs compared with the post-thawing injections, as evidenced by higher emulsion creaming index, oil droplet size, interfacial absorptive protein amount, and viscoelasticity. Additionally, the pre-freezing injections could effectively mitigate the damage to the gelling properties of MPs, as evidenced by the formation of a homogeneous and compact gel network with stronger water retention, strength and chemical forces, as well as a higher proportion of non-flowing water, whereas the post-thawing injections could not. These results demonstrated that the injection of l-arginine and l-lysine solution before freezing could delay freezing-induced damage to the emulsifying and gelling properties of MPs, keeping the processing characteristics of frozen porcine.

Improved gelling and emulsifying properties of chicken wooden breast myofibrillar protein by high-intensity ultrasound combination with pH-shifting

The functional properties of chicken wooden breast myofibrillar protein (WBMP) are impaired. The protein structure and functional properties of WBMP are investigated using high-intensity ultrasound (HIU, 20 kHz, 200, 400, 600, and 800 W) combined with pH-shifting. HIU promoted the unfolding of WBMP, reduced the particle size of WBMP, and enhanced electrostatic repulsion. Medium-power (200 and 400 W) HIU promoted the α-helix to β-sheet transformation, while high-power (600 and 800 W) HIU significantly (P < 0.05) increased the content of the random coil. The microstructure and images after storage further showed that 400 W HIU in combination with pH-shifting made the WBMP emulsion more uniform. In addition, gel performance analysis showed that the gel strength and water-holding capacity of the protein gel increased gradually after 400 W. Scanning electron microscope images also showed the formation of a stable network structure in the protein gel. This work could help promote the utilization of inferior proteins similar to WBMP, but the utilization rate still needs to be further improved.

Effect of ultrasound treatment on thawing process of frozen tofu prepared with different salt coagulants

This study investigated the effects of ultrasound-assisted water thawing (UWT) at different power levels (0, 100, 150, 200, and 250 W) on the thawing rate and gel properties of frozen tofu made using three different salt coagulants (CaCl2, CaSO4, and MgCl2). Tofu produced with CaCl2 and CaSO4 elicited gel structures with dense and homogeneous networks, while that with MgCl2 had rough pores and irregular networks. UWT treatment significantly decreased thawing time by 30.9-53.5% compared to the control. Water holding capacity and scanning electron microscopy analyses demonstrated that UWT-100, UWT-150, and UWT-200 should be used to increase the amount of fixed water for CaCl2, CaSO4, and MgCl2. These findings suggest that appropriate ultrasonic treatment could improve the water retention capacity of the tofu network and make the gel network structure more compact. Additionally, protein structural analysis showed a decrease in the exposure of hydrophobic groups and reduced protein denaturation when tofu prepared with all the coagulants were thawed with UWT energies of 100-200 W ultrasonication. These findings offer theoretical support for improving the frozen tofu thawing process while ensuring optimal final product quality.

Physicochemical and structural changes of myofibrillar proteins in muscle foods during thawing: Occurrence, consequences, evidence, and implications

Myofibrillar protein (MP) endows muscle foods with texture and important functional properties, such as water-holding capacity (WHC) and emulsifying and gel-forming abilities. However, thawing deteriorates the physicochemical and structural properties of MPs, significantly affecting the WHC, texture, flavor, and nutritional value of muscle foods. Thawing-induced physicochemical and structural changes in MPs need further investigation and consideration in the scientific development of muscle foods. In this study, we reviewed the literature for the thawing effects on the physicochemical and structural characters of MPs to identify potential associations between MPs and the quality of muscle-based foods. Physicochemical and structural changes of MPs in muscle foods occur because of physical changes during thawing and microenvironmental changes, including heat transfer and phase transformation, moisture activation and migration, microbial activation, and alterations in pH and ionic strength. These changes are not only essential inducements for changes in spatial conformation, surface hydrophobicity, solubility, Ca2+ -ATPase activity, intermolecular interaction, gel properties, and emulsifying properties of MPs but also factors causing MP oxidation, characterized by thiols, carbonyl compounds, free amino groups, dityrosine content, cross-linking, and MP aggregates. Additionally, the WHC, texture, flavor, and nutritional value of muscle foods are closely related to MPs. This review encourages additional work to explore the potential of tempering techniques, as well as the synergistic effects of traditional and innovative thawing technologies, in reducing the oxidation and denaturation of MPs and maintaining the quality of muscle foods.

Improvement of the emulsifying properties of mixed emulsifiers by optimizing ultrasonic-assisted processing

Optimizing ultrasound (ULD)-assisted flavonoid modification is an important component of enhancing its application potential. In this work, diverse flavonoids, such as quercetin (Que), apigenin (Api), and morin (Mor), were used to modify protein in myofibrillar protein (MP)/cellulose nanocrystal (CN) complexes using ULD-assisted method. Compared with the MP/CNs group, the triiodide contents of MP-Que/CNs, MP-Api/CNs, and MP-Mor/CNs increased by 1175.84%, 479.05%, and 2281.50% respectively. The findings revealed that the actual intensity of ULD was drastically reduced by the molecular weight decrease of these flavonoids. For olive oil emulsions prepared with mixed emulsifiers, the low interfacial diffusion rates (0.03 mN·m·s-1/2) and weak emulsifying activity (8.33 m2/g) of the MP/CN complexes were significantly improved by the flavonoids after ULD-assisted treatment. Notably, the emulsions prepared using MP-Api/CNs contained smaller oil droplets and exhibited better emulsifying properties, compared to emulsions prepared with MP-Mor/CNs or MP-Que/CNs. This study is essential for ULD-assisted treatment since the processing impact may be increased by choosing the most suitable flavonoid.

Effects of electric and magnetic field on freezing characteristics of gel model food

The novel freezing technologies including electrostatic field assisted freezing (EF), static magnetic field assisted freezing (MF), electrostatic field combined with static magnetic field assisted freezing (EMF) were conducted on model food to facilitate comparing their application effect. The results show that the effect of EMF treatment was best, which significantly changed the freezing parameters of the sample. Compared with the control, the phase transition time and total freezing time were shortened by 17.2% and 10.5%, respectively; the proportion of the sample free water content detected by low-field nuclear magnetic resonance was significantly decreased; the gel strength and hardness were significantly improved; the protein secondary and tertiary structures were better maintained; the ice crystal area was reduced by 49.28%. Inverted fluorescence and scanning electron microscopic results indicated that the gel structure of EMF treatment samples was better than MF and EF. MF was less effective in maintaining the quality of frozen gel model.

Effects of κ-carrageenan gum on 3D printability and rheological properties of pork pastes

The effects of κ-carrageenan gum (KG) on the 3D printability and rheological properties of pork pastes were investigated in this study. There were five groups with different levels of KG (0, 2, 4, 6, and 8 g/kg) named as KG-0, KG-2, KG-4, KG-6, and KG-8, respectively. The addition of KG increased the yield stress, viscosity, shear stress, recovery percentage, storage modulus, loss modulus, and initial and average flow forces (P < 0.05). The results of low-field nuclear magnetic resonance analysis revealed that addition of KG reduced T₂₁ and T₂₂ (P < 0.05). The best printing parameters were obtained by accuracy and stability results: printing filling percent, 90%; printing speed, 35 mm⋅s^-1; layer height, 2 mm; nozzle diameter, 1.55 mm, and KG addition level, 6 g/kg. KG addition improved the hardness, springiness, chewiness, cohesiveness, adhesiveness, and density, respectively (P < 0.05). The results suggested that KG addition improved the rheological properties and 3D printability of the pork pastes.

The Effects of Malonaldehyde on Quality Characteristics and Protein Oxidation of Coregonus peled (Coregonuspeled) during Storage

The effects of changes in the malondialdehyde (MDA) content on the quality of fish during the low-temperature storage period are unclear. Therefore, the effects of the MDA content on Coregonus peled quality and protein changes were investigated following storage under refrigeration (4 °C) and super chilling (-3 °C) for 15 days (d). The results showed that the MDA content continued to increase during storage and that the highest content was produced at 1.42 mg/kg during refrigeration. The fillet pH, drip loss, texture (hardness and elasticity), and myofibril fragmentation index deteriorated significantly during the storage period. Increased oxidation of the myofibrillar protein (MP) was observed in the 15 d storage period, and the MP carbonyl content was 1.19 times higher under refrigeration than in super chilling, while the protein α-helix structure decreased by 12.48% and 12.20% under refrigeration and super chilling, respectively. Electropherograms also showed that myosin degradation was particularly severe in the refrigeration storage period of 15 d. Overall, the MDA formed at the refrigeration and super chilling storage temperatures could promote structural changes in, and the oxidative degradation of, proteins to different degrees, leading to the deterioration of the fillet quality. This study provides a scientific basis for investigating the relationship between fish quality and changes in the MDA content during low-temperature storage.

Interaction between Kidney-Bean Polysaccharides and Duck Myofibrillar Protein as Affected by Ultrasonication: Effects on Gel Properties and Structure

The interaction of polysaccharides-protein with varied origins and structures provides opportunities for tailoring the physicochemical qualities of food protein-based materials. This work examined the feasibility of ultrasound-modified interaction between kidney bean dietary fiber (KSDF) and duck myofibrillar proteins (MP) to improve the physicochemical properties of the gel matrices. Accordingly, gel strength, water holding capacity, solubility, chemical interaction, secondary structure, and network structure of MP were determined. The addition of KSDF combined with the ultrasound treatment contributed to the improved water retention capability, G' values, and the reduced particle size of protein molecules, corresponding with the formation of dense pore-like structures. The results demonstrated that 1% KSDF and ultrasonication at 400 W significantly enhanced gel strength by up to 109.58% and the solubility increased by 213.42%. The proportion of α-helices of MP gels treated with 1% KSDF and ultrasonication at 400 W was significantly increased. The sonication-mediated KSDF-MP interaction significantly improved hydrophobic interactions of the proteins, thus explaining the denser network structure of the MP gels incorporated KSDF with ultrasound treatments. These results demonstrated the role of ultrasonication treatments in modifying KSDF-protein interaction to improve the gel and structural properties of the MP gels.

Research progress on quality deterioration mechanism and control technology of frozen muscle foods

Freezing can prolong the shelf life of muscle foods and is widely used in their preservation. However, inevitable quality deterioration can occur during freezing, frozen storage, and thawing. This review explores the eating quality deterioration characteristics (color, water holding capacity, tenderness, and flavor) and mechanisms (irregular ice crystals, oxidation, and hydrolysis of lipids and proteins) of frozen muscle foods. It also summarizes and classifies the novel physical-field-assisted-freezing technologies (high-pressure, ultrasound, and electromagnetic) and bioactive antifreeze (ice nucleation proteins, antifreeze proteins, natural deep eutectic solvents, carbohydrate, polyphenol, phosphate, and protein hydrolysates), regulating the dynamic process from water to ice. Moreover, some novel thermal and nonthermal thawing technologies to resolve the loss of water and nutrients caused by traditional thawing methods were also reviewed. We concluded that the physical damage caused by ice crystals was the primary reason for the deterioration in eating quality, and these novel techniques promoted the eating quality of frozen muscle foods under proper conditions, including appropriate parameters (power, time, and intermittent mode mentioned in ultrasound-assisted techniques; pressure involved in high-pressure-assisted techniques; and field strength involved in electromagnetic-assisted techniques) and the amounts of bioactive antifreeze. To obtain better quality frozen muscle foods, more efficient technologies and substances must be developed. The synergy of novel freezing/thawing technology may be more effective than individual applications. This knowledge may help improve the eating quality of frozen muscle foods.

Effects of ultrasonic-microwave combination treatment on the physicochemical, structure and gel properties of myofibrillar protein in Penaeus vannamei (Litopenaeus vannamei) surimi

The objective of this study was to evaluate the effects of single ultrasound (360 W, 20 min), single microwave (10 W/g, 120 s) and ultrasonic-microwave combination treatment on shrimp surimi gel properties. The structure and physicochemical properties of myofibrillar protein (MP) were also determined. Low-field nuclear magnetic resonance showed that the fluidity of water molecules and the moisture content decreased, the stability and water holding capacity (WHC) increased after single ultrasound, single microwave and ultrasonic-microwave combination treatment. Compared with the traditional water bath treatment, ultrasound and microwave treatment reduced the total sulfhydryl content and promoted the formation of intermolecular disulfide bonds and hydrophobic interactions, which improved the compactness of the network structure of shrimp surimi gel. Moreover, Fourier transform infrared spectroscopy and sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis revealed that these treatments not only inhibited the degradation of MP, but also decreased the α-helix content and increased the β-sheet content. The three treatments also significantly reduced the particle size and decreased the solubility of MP. Overall, the effect of ultrasonic-microwave combination treatment was superior to that of either single treatment.

Effects of single-, dual-, and multi-frequency ultrasound-assisted freezing on the muscle quality and myofibrillar protein structure in large yellow croaker (Larimichthys crocea)

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MUAF significantly promoted the freezing process of large yellow croakers.

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MUAF enhanced the quality of large yellow croakers.

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MUAF better maintained the stability of fish protein.

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The mechanisms of single-, dual-, and multi-frequency UAF were analyzed.

Ultrasound-assisted freezing (UAF) has been proved to be a new technology to improve the quality of frozen foods. Frequency is an important parameter affecting UAF result. This study was to investigate the effects of single-, dual- and multi-frequency UAF on muscle quality and myofibrillar protein structure in large yellow croaker (Larimichthys crocea), providing reference for the application of multi-frequency UAF in frozen foods. Multi-frequency UAF increased the freezing rate and had lower thawing loss, thiobarbituric acid reactive substances (TBARS) value, total volatile basic nitrogen (TVB-N) value, and higher immobilized water content. Multi-frequency UAF had lower carbonyl, higher sulfhydryl content, and more stable myofibrillar protein secondary and tertiary structures. Confocal laser scanning microscopy (CLSM) indicated that the filamentous polymer in muscle fibrin solution with multi-frequency UAF was transformed into more evenly distributed units. In general, multi-frequency UAF significantly improved the freezing rate, reduced lipid oxidation, and maintained the myofibrillar structure.

Ultrasound-assisted modification of gelation properties of proteins: A review

Protein gels have diverse applications in the food, pharmaceutical, and cosmetic sectors due to their affordability, biodegradability, and edibility. However, the inherent properties of some native proteins have a few drawbacks that have to be tailored to meet the needs of specific functions as the food ingredients. The protein gelation properties mainly depend on the protein molecular structure, primarily the folding and unfolding of secondary structural elements (α-helix and β-sheets) with distinctive functions. In the past, a great amount of work (thermal, chemical, and enzymatic methods) has been carried out to enhance the gelation and functional properties of proteins. Recently, the traditional methods have been replaced with non-thermal physical methods that enhance the properties for better applications. One such approach is the use of ultrasonic technology as a low-cost green technology to modify the molecular orientation attributed to the native chemistry and functionality of that proteins. Ultrasonic technology is important in food systems and can be effectively used as an alternative method to improve the protein gelling characteristics to form high-quality gels. This article is aimed to comprehensively collate some of the vital information published on the mechanism of protein gelation by ultrasonication and review the effects of ultrasound-assisted extraction and treatments on gelation properties of different proteins. The enhanced gelation properties by the ultrasound application open a new stage of technology that enables the proteins for better utilization in the food processing sector.

Comparative study on the in vitro digestibility of chicken protein after different modifications

The effects of tea polyphenols (TPPs) and ultrasound treatment (UDT) on the digestibility of chicken myofibrillar protein (MPN) in anenhanced oxidation system were investigated. As observed, the original aggregates of MPN were much lower in the UDT-assisted group than in the control protein group, and the difference widened after the incorporation of TPPs. The covalent structures of the UDT-assisted oxidation groups were verified via mass spectrometry and amino acid (AAD) measurements. The peptide abundance increased after the UDT-assisted covalent reaction and most of these peptides were derived from the structural proteins of MPNs according to the results of nano-LC-ESI-MS/MS. Digestion kinetic analysis showed that the digestion level of the EGCG-treated group was better than that of the other treated groups, regardless of the UDT-assisted covalent reaction. Overall, the combination of EGCG oxidation and UDT may be an efficient way to promote the nutritional value of the final MPN products.

Effects of ultrasound-assisted immersion freezing on the muscle quality and myofibrillar protein oxidation and denaturation in Sciaenops ocellatus

Freezing is a method that plays a key role in the storage of aquatic products. The effects of different methods of freezing on the quality, microstructure, ice-crystal morphology, and protein oxidation of Sciaenops ocellatus were investigated. Air freezing (AF), immersion freezing (IF), and different powers of ultrasound-assisted immersion freezing (UIF) (150, 200, and 250 W) were studied. IF and UIF significantly improved the freezing rate of S. ocellatus and shortened the freezing time by more than 83% compared with AF. The freezing rate achieved using UIF (200 W) was 712.81% higher than that achieved using AF. Oxidative denaturation of the myofibrillar protein was reduced after 90 days of frozen storage. Moreover, frozen samples in the UIF-200 W group had higher protein stability compared with that in the other groups. Therefore, appropriate ultrasonic power (200 W) during freezing can accelerate the freezing process of S. ocellatus and maintain its muscle quality.

New insights into the ultrasound impact on covalent reactions of myofibrillar protein

In this work, two different covalent reactions, namely, alkaline reaction and free radical oxidation, were selected to compare the difference in the strengthening effects of ultrasound treatment (UDT). The grafting effects were verified by protein electrophoresis and bound gallic acid (GA) assay. Furthermore, non-covalent interactions between myofibrillar protein (MPN) aggregates were destroyed by UDT, as proved by the lower particle sizes and higher ζ-potential. Comparatively, the results from tertiary structure index and circular dichroism revealed UDT-assisted free radical oxidation could lead to better conjugates with greater structural properties. The atomic force microscope (AFME) and protein flexibility showed that MPNs appeared to display as irregular spherical particles after alkaline reaction, however, maintained fibrous structure during the free radical oxidation. Consequently, the combination of UDT and free radical oxidation were more effectively for strengthening the influence of acoustic cavitation on MPNs, of which mechanism was the changes in viscosity properties, microstructure and acoustic cavitation radicals.

Novel synergistic freezing methods and technologies for enhanced food product quality: A critical review

Freezing has a long history as an effective food preservation method, but traditional freezing technologies have quality limitations, such as the potential for water loss and/or shrinkage and/or nutrient loss, etc. in the frozen products. Due to enhanced quality preservation and simpler thawing operation, synergistic technologies for freezing are emerging as the optimal methods for frozen food processing. This article comprehensively reviewed the recently developed synergistic technologies for freezing and pretreatment, for example, ultrasonication, cell alive system freezing, glass transition temperature regulation, high pressure freezing, pulsed electric field pretreatment, osmotic pretreatment, and antifreeze protein pretreatment, etc. The mechanisms and applications of these techniques are outlined briefly here. Though the application of new treatments in freezing is relatively mature, reducing the energy consumption in the application of these new technologies is a key issue for future research. It is also necessary to consider scale-up issues involved in large-scale applications as much of the research effort so far is limited to laboratory or pilot scale. For future development, intelligent freezing should be given more attention. Freezing should automatically identify and respond to different freezing conditions according to the nature of different materials to achieve more efficient freezing. PRACTICAL APPLICATION: This paper provides a reference for subsequent production and research, and analyzes the advantages and disadvantages of different novel synergistic technologies, which points out the direction for subsequent industry development and research. At the same time, it provides new ideas for the freezing industry.

Effects of Ultrasound-Assisted Vacuum Impregnation Antifreeze Protein on the Water-Holding Capacity and Texture Properties of the Yesso Scallop Adductor Muscle during Freeze-Thaw Cycles

The effect of antifreeze protein (AFP) on the water-holding capacity (WHC) and texture properties of the Patinopecten yessoensis adductor muscles during freeze–thaw cycles (FTCs) were evaluated based on three impregnation methods: general impregnation (GI), vacuum impregnation (VI), and ultrasound-assisted VI (US-VI). The WHC, texture properties, and tissue microstructure were all evaluated. Results showed that the WHC and texture properties of adductor muscle were significantly improved in the VI and US-VI groups during FTCs (p < 0.05). The WHC of the adductor muscle in the US-VI group was maximally enhanced in terms of yield (6.63%), centrifugal loss, cooking loss, and T₂₂. The US-VI group of the adductor muscle had the optimal chewiness and springiness compared to others, and the shear force and hardness were most effectively enhanced by VI. The growth and recrystallization of ice crystals in the frozen adductor muscle were significantly inhibited by VI and US-VI. The average cross-sectional area and roundness of ice crystals in the US-VI group were decreased by 61.89% and increased by 22.22% compared with those of the control, respectively. The partial least squares regression (PLSR) model further confirmed that the WHC and texture properties of the adductor muscle were correlated appreciably with the degree of modification of ice crystal morphology through the AFP.

Recent development in evaluation methods, influencing factors and control measures for freeze denaturation of food protein

Frozen storage is most widely adopted preservation method to maintain food freshness and nutritional attributes. However, at low temperature, food is prone to chemical changes such as protein denaturation and lipid oxidation. In this review, we discussed the reasons and influencing factors that cause protein denaturation during freezing, such as freezing rate, freezing temperature, freezing method, etc. From the previous literatures, it was found that frozen storage is commonly used to prevent freeze induced protein denaturation by adding cryoprotectants to food. Some widely used cryoprotectants (for example, sucrose and sorbitol) have been reported with higher sweetness and weaker cryoprotective abilities. Therefore, this article comprehensively discusses the new cryopreservation methods and providing comparative study to the conventional frozen storage. Meanwhile, this article sheds light on the freeze induced alterations, such as change in functional and gelling properties. In addition, this article could be helpful for the prolonged frozen storage of food with minimum quality related changes. Meanwhile, it could also improve the commercial values and consumer satisfaction of frozen food as well.

Effects of three treatments on protein structure and gel properties of Perccottus glenii myofibrillar protein

In order to improve Perccottus glenii myofibrillar protein (MP) gel properties, three treatments were evaluated: ultrasonic, transglutaminase (TGase) and combined ultrasonic-transglutaminase treatments. Combined ultrasonic-transglutaminase treatment altered protein structure and gel properties most dramatically. As compared with untreated control group protein, treated protein gels possessed decreased sulfhydryl group content and increases in water holding capacity, whiteness value and hydrophobic interactions that increased gel strength value by up to 3.79 times that of untreated protein gel. Protein structural and Differential scanning calorimetry (DSC) analyses revealed that combined ultrasonic-TGase treatment increased both protein thermal denaturation temperature and UV absorbance (as compared to control and other treatment groups) that supported formation of MP gels with desirable characteristics. These results provide a theoretical basis for development of superior MP gels to promote greater utilization of this fish protein resource by the food industry.

Emulsion gels stabilized by soybean protein isolate and pectin: Effects of high intensity ultrasound on the gel properties, stability and β-carotene digestive characteristics

In this study, soybean protein isolate (SPI) and pectin emulsion gels were prepared by thermal induction, and the effects of high intensity ultrasound (HIU) at various powers (0, 150, 300, 450 and 600 W) on the structure, gel properties and stability of emulsion gels were investigated. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) showed that the interaction between SPI and pectin was enhanced and the crystallinity of the emulsion gels was changed due to the HIU treatment. Confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) observations revealed that the particle size of the emulsion gels was decreased significantly by HIU treatment. The emulsion gel structure became more uniform and denser, which was conducive to storage stability. In addition, according to the low field nuclear magnetic resonance (LF-NMR) analysis, HIU treatment had no obvious impact on the content of bound water as the power increased to 450 W, while the content of free water decreased gradually and became immobilized water, which indicated that the water holding capacity of the emulsion gels was enhanced. Compared with untreated emulsion gel, differential scanning calorimetry (DSC) analysis showed that the denaturation temperature reached 131.9 ℃ from 128.2 ℃ when treated at 450 W. The chemical stability and bioaccessibility of β-carotene in the emulsion gels were improved significantly after HIU treatment during simulated in vitro digestion.

The impact of quick-freezing methods on the quality, moisture distribution and microstructure of prepared ground pork during storage duration

The aim of present study was to investigate the influences of ultrasound-assisted immersion freezing (UIF), immersion freezing (IF) and air freezing (AF) on the quality, moisture distribution and microstructure properties of the prepared ground pork (PGP) during storage duration (0, 15, 30, 45, 60, 75 and 90 days). UIF treatment significantly reduced the freezing time by 60.32% and 39.02%, respectively, compared to IF and AF (P < 0.05). The experimental results of quality evaluation revealed that the L* and b* values, juice loss, cooking loss, TBARS values and carbonyl contents were decreased in the UIF treated samples, while the a* value, peak temperatures (Tm), enthalpy (ΔH) and sulfhydryl contents were significantly higher than those of IF and AF treated samples (P < 0.05). In addition, low-field nuclear magnetic resonance (LF-NMR) and differential scanning calorimetry (DSC) analysis demonstrated that UIF inhibited the mobility of immobilized water and reduced the loss of immobilized and free water, and then a high water holding capacity (WHC) was achieved. Compared to the IF and AF treatments, the UIF treated PGP samples possessed better microstructure. Therefore, UIF could induce the formation of ice crystals with smaller size and more even distribution during freezing process, which contributed to less damage to the muscle tissue and more satisfied product quality.

Effect of rutin on the physicochemical and gel characteristics of myofibrillar protein under oxidative stress

The effects of rutin (6, 30, and 150 μmol/g_pro ) on the physicochemical, structural properties and gel characteristics of myofibrillar protein (MP) under oxidative stress were investigated. The addition of rutin significantly promoted the formation of oxidized MP carbonyl derivatives and dimer tyrosine, but it cannot prevent the loss of sulfhydryl groups (-SH). With increasing rutin concentration, the hydrophobic area was gradually shielded and rutin acted as a quencher to reduce the fluorescence intensity of oxidized MP. Under the oxidative stress, rutin increased the particle size and aggravated the cleavage of protein molecules. SDS-polyacrylamide gel electrophoresis revealed that rutin further aggravated oxidized MP degradation and cross-linked form polymer which cross-linked with protein to the maximum extent at 150 μmol/g_pro rutin content. Moderate cross-linking between protein and rutin could improve the gel strength and water holding capacity (WHC) of oxidized MP gel. For rutin concentrations of 6 and 30 μmol/g_pro , the gels had denser network structures, as observed by scanning electron microscopy. PRACTICAL APPLICATIONS: Polyphenols of the type and dosage can change the properties of the product itself and optimize the quality of product processing. Certain polyphenols may promote the oxidation process of protein-rich products, but this does not affect the improvement of product quality. The application of natural polyphenols is the promising business direction in the development of Coregonus peled industry.

Review of ultrasound combinations with hybrid and innovative techniques for extraction and processing of food and natural products

Ultrasound has a significant effect on the rate of various processes in food, perfume, cosmetic, pharmaceutical, bio-fuel, materials, or fine chemical industries, despite some shortcomings. Combination with other conventional or innovative techniques can overcome these limitations, enhance energy, momentum and mass transfer, and has been successfully demonstrated in many recent studies. Various ultrasound combined hybrid and innovative techniques are systematically summarized in this review for the first time. Ultrasound can be combined with diverse conventional techniques including Soxhlet, Clevenger, enzyme, hydrotropes, ionic liquids, Deep Eutectic Solvents (DES) or Natural Deep Eutectic Solvents (NADES), to enhance mixing and micro-mixing, reduced thermal and concentration gradients, and selective extraction. Moreover, combinations of ultrasound with other innovative techniques such as microwave, extrusion, supercritical fluid, subcritical and pressure liquids, Instant controlled pressure drop (DIC), Pulsed Electric Field (PEF), Ultra-Violet (UV) or Infra-Red (IR) radiations, Counter-current chromatography (CCC), or centrifugal partition chromatographs (CPC) can enable reduced equipment size, faster response to process control, faster start-up, increased production, and elimination of process steps. The theories and applications of these ultrasound combined hybrid and innovative techniques as well as their advantages and limitations are compared, and further perspectives are proposed. This review provides new insights into advances in ultrasound combined techniques and their application at research, educational, and industrial level in modern food and plant-based chemistry.

Ultrasonic structural modification of myofibrillar proteins from Coregonus peled improves emulsification properties

This study evaluated the effects of high intensity ultrasonication (HIU, 100, 150, 200, and 250 W) and treatment time (0, 3, 6, 9, and 12 min) on the structure and emulsification properties of myofibrillar proteins (MPs) from Coregonus peled. These investigations were conducted using an ultrasonic generator at a frequency of 20 kHz (ultrasonic probe). Analysis of the carbonyl content and total number of sulfhydryl groups showed that HIU significantly improved the oxidative modification of MPs (P < 0.05). SDS-PAGE profiling showed significant degradation of the myosin heavy chain (P < 0.05). In addition, Fourier transformed infrared spectroscopy (FTIR) revealed that HIU altered these treated MP secondary structures, this was due to molecular unfolding and stretching, exposing interior hydrophobic groups. Particle size analysis showed that HIU treatment reduced particle sizes. Solubility, emulsification capacity, and emulsion stability were improved significantly, and each decreased with an increase in treatment time (up to 12 min), indicating aggregation with prolonged sonication. These results indicate that HIU could improve the emulsification properties of MPs from C. peled, demonstrating a promising method for fish protein processing.

Ultrasound-assisted covalent reaction of myofibrillar protein: The improvement of functional properties and its potential mechanism

The effects of the different combined manner of ultrasound and covalent reaction between polyphenol and myofibrillar protein (MP) from chicken were studied. More so, antioxidant activities, digestive properties, and potential mechanism of ultrasound-assisted oxidation system of hydrophilic ((-)-Epicatechin gallate, ECG) and hydrophobic (Baicalein, BN) polyphenols was also analyzed in this study. Among all the combined treatments, surface hydrophobicity (SUH), active sulfhydryl contents (ASC), and specific surface area (SSA) of ultrasonic assisted ECG oxidation group (T6) was relatively apparent, indicating that a more unfolding MP structure was obtained. Furthermore, ultrasonic assisted ECG oxidation group showed the highest antioxidant activities compared with other combined treatments on the basis of the results of DPPH free radical scavenging activities, metal ion chelating activities, and hydroxyl radicals (OH·) scavenging activities. The results of simulated digestion system and kinetic analysis also verified that ultrasonic assisted ECG oxidation had higher MP bio-accessibility than the control group. In contrast, a lower digestibility was displayed in ultrasonic assisted BN oxidation group. In summary, the ultrasound-assisted covalent reaction of MP and ECG might be a desirable approach for industrial production of MP from chicken with better antioxidant activities and digestive properties.

Effectiveness of ultrasound-assisted immersion thawing on the thawing rate and physicochemical properties of chicken breast muscle

This study evaluated the effect of air thawing (AT), water thawing (WT), and ultrasound-assisted immersion thawing (UT) at different power levels (200, 300, 400, and 500 W) on the thawing rate, physicochemical properties, and protein structure of chicken breast muscle (pectoralis), and the weight of each sample was approximately 106 ± 3 g. UT shortened the total thawing time and decreased the cutting force with increasing ultrasound power. Additionally, UT at 300 W (UT-300) remarkably reduced the thawing and cooking losses of the samples compared to AT, WT, and other UT powers (p < 0.05). Low-field nuclear magnetic resonance spectroscopy showed that the T₂₁ and T₂₂ of the UT-300 samples were shorter than those of the AT and WT samples (p < 0.05), which revealed that UT-300 reduced the mobility and losses of both immobilized and free water. Moreover, UT-300 remarkably reduced the damage to the myofibrillar protein (MP) structure. Overall, with appropriate ultrasonic power, the thawing rate increased and changes in the MP structure were reduced. PRACTICAL APPLICATION: This study found that compared to that of AT samples, the thawing time of the UT-300 samples markedly decreased by 57%. In addition, UT-300 could reduce the damage to the myofibrillar protein structure, which was very beneficial for further processing of frozen foods.

Optimization of ultrasonic-assisted freezing of Penaeus chinensis by response surface methodology

Objectives

Optimization of ultrasonic-assisted freezing of Penaeus chinensis by response surface methodology was studied in order to (1) obtain frozen Penaeus chinensis of high quality and (2) provide practical guidance for the application of ultrasonic-assisted freezing in Penaeus chinensis.

Materials and Methods

Three independent and major variables were selected, including initial ultrasonic temperature (°C), ultrasonic power (W) and ultrasonic time (s on/2 s off). On the basis of one-factor experiments, 17 groups of experiments were established by response surface methodology according to Box–Behnken design. Using multiple regression analysis the experimental data were fitted into a second-order polynomial equation, which was tested by proper statistical methods.

Results

The optimal ultrasonic conditions were as follows: initial ultrasonic temperature 0 °C, ultrasonic power 180 W, ultrasonic time 5 s on/2 s off. Under the optimization conditions, the time of passing through maximum ice crystal generation zone was 105.500 s, which was very close to the predictive passage time of 101.541 s.

Conclusions

Initial ultrasonic temperature, ultrasonic time and ultrasonic power played an important role in the process of ultrasonic-assisted freezing of Penaeus chinensis. Response surface methodology was used to optimize the three factors in ultrasonic-assisted freezing, which could greatly shorten the time of passing through the maximum ice crystal generation zone and maintain the tissue structure of Penaeus chinensis well.

Physicochemical and structural changes in myofibrillar proteins from porcine longissimus dorsi subjected to microwave combined with air convection thawing treatment

The effect of microwave combined with air convection thawing (MAT) on the properties and tertiary structure of myofibrillar proteins (MPs) from porcine longissimus dorsi muscle was investigated and compared with single treatments (air thawing, microwave thawing) and fresh meat (FM). Among the thawing treatments, the carbonyl content, dityrosine content, and surface hydrophobicity of MPs in MAT were the lowest, whereas the total sulfhydryl content, water-holding capacity, and Ca²⁺-ATPase activity were the highest, suggesting that MAT retained MPs properties better. MAT possessed a more stable tertiary structure and exhibited slight changes in MPs aggregation and degradation. There was an insignificant difference (P > 0.05) in the immobilized water and free water between the MAT samples and FM, indicating a tighter interaction between water and muscle protein in MAT. Thus, MAT could retain the physicochemical and structural properties of MPs, which provided a combination of thawing treatments for application in meat industry.