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Abstract The effects of combinations of high pressure and heat on chicken myofibrillar gels were investigated. High pressure was either applied simultaneously with heating (heating under pressure, HUP), before heating (PBH) or no high pressure with heat-only (HT). PBH treatment induced many similar properties in gels as did by HT treatment, except that PBH treatment promoted secondary structure transformation and formed more covalent bonds. HUP treatment resulted in less heat denaturation of the protein, induced fewer hydrophobic interactions and covalent bonds, hindered secondary and tertiary structural transformation, and formed a gel with a more porous microstructure. The gels induced by HUP treatment had softer texture and higher water holding capacity than gels induced by PBH or HT treatments. These findings suggest that high pressure with HUP treatment changes gel properties by resisting the heat-induced denaturation and gelation of myofibrillar proteins, while high pressure with PBH treatment alters gel properties by promoting denaturation of myofibrillar proteins. Industrial relevance The main constituents in meat are myofibrillar proteins, which are responsible for the functional properties of processed meat products. The gelation of myofibrillar proteins differs according to the sequence in which pressure/temperature combinations are applied. The pressure-modified protein interactions should be considered when adopting high pressure in meat product processing since the microstructure of the meat gel is affected by pressure, which would further affect water holding capacity and textural properties. HUP treatment showed its advantages in forming a fine microstructure and improving water-holding capacity. Highlights • High pressure modified the heat-induced gelling of myofibrillar proteins. • Heat-induced protein structural transformation was retained by high pressure. • The gel induced by heating under pressure had a uniform porous microstructure. • The gel induced by heating under pressure had a high water holding capacity. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The pure MP gelation had a loose and dispersed network with interconnected water channels. • The MP gelation was significantly improved by IDF addition. • IDF addition eliminate interconnected water channels in the gelation network. • The IDF addition promoted to the protein aggregation during thermal process. Abstract The effects of insoluble dietary fiber (IDF) on heat-induced gelation properties, such as microstructural changes and the molecular conformation of myofibrillar proteins (MP), were analyzed by image analyses and Raman spectroscopy. Scanning electron microscopy revealed that pure MP gelation contained a loose and dispersed network with interconnected water channels. With IDF addition, the lacunarity and the particle size of water pores both significantly decreased (P < 0.05) and fractal dimension significantly increased (P < 0.05), which indicated the formation of a homogenous and compact three-dimensional network. Through Raman spectra, IDF addition resulted in modification of amide I and III regions, by a significant decrease in α-helix content, accompanied by an increase of β-sheets, β-turns, and random coil content (P < 0.05); the intensity of CU+005CH stretching vibrations bending vibrations bands were significantly decreased (P < 0.05). Principal component analyses showed significant correlations between textual property, microstructure and molecular conformations. Cluster analyses indicated IDF improved the functionality of MP gel by 1): IDF stable the moisture phase 2) "concentrated" MP promoted structural integrity and compact gelation. [ABSTRACT FROM AUTHOR]

The effects of sugarcane insoluble dietary fiber (SIDF) on water holding capacity (WHC), gel strength, microstructure, and secondary structures of myofibrillar protein (MP) gels were studied. The gel strengths and WHC were improved with the increase of SIDF content. Paraffin section showed that SIDF did not have direct contact with the MP and was simply trapped in the gel network. The SEM micrograph indicated that water channels appeared through the pure MP gel network, so the integrity of gel network and the gelation quality would de deteriorated. The SIDF acted as active dehydrating agent and change the water distribution. Hence, the water channels disappeared in the internal of heat-induced gelation, which promote to aggregate compact and well-linked gel structure. The analysis of T 2 relaxation revealed that T 21 relaxation time of MP gel decreased significantly with SIDF addition, which indirectly suggested that the gel with SIDF had better three-dimension network and could bind the water more firmly. Raman spectroscopic study showed the SIDF addition resulted in the left shift and right shift of characteristic peak in Amide I and Amide III of the gelation, respectively. Moreover, the intensity of characteristic peak in aliphatic residues band also had a significant decrease. The changes of Raman spectroscopy reflected the SIDF addition have the positive effect on forming firm and compact MP gel. [ABSTRACT FROM AUTHOR]

Development of healthier meat products is needed to meet consumers' request. The effects of dietary fiber addition on the water distribution, water binding capacity (WBC), and textural properties of a fat-reduced model meat system enriched with inulin, cellulose, carboxymethyl cellulose (CMC), chitosan, pectin, respectively, were investigated in this study. The fibers were incorporated in powder form to constitute 2% (w/w) of the meat batter. In general, fiber enrichment resulted in significant lower cooking loss and improved WBC, while the impact on texture was dependent on the specific dietary fiber. Low-field NMR relaxometry revealed that chitosan impacted the heating-induced changes in water distribution differently from other fibers and that CMC had a higher capability to counteract the impact of heat-induced protein denaturation on water expulsion than the other fiber types. It is anticipated that this knowledge is useful in the development of novel strategies where dietary fiber enrichment is optimized to promote specific and desired technological attributes of healthy meat products. [ABSTRACT FROM AUTHOR]

Protein structural changes and water mobility properties in chicken liver paste batters prepared with plant oil (sunflower and canola oil combinations) substituting 0–40% pork back-fat combined with pre-emulsification were studied by Raman spectroscopy and low-field nuclear magnetic resonance (NMR). Results showed that pre-emulsifying back-fat and plant oil, including substituting higher than 20% back-fat with plant oil increased the water- and fat-binding ( p < 0.05) properties, formed more even and fine microstructures, and gradually decreased the NMR relaxation times ( T 21a , T 21b and T 22 ), which was related to the lower fluid losses in chicken liver paste batters. Raman spectroscopy revealed that compared with a control, there was a decrease ( p < 0.05) in α-helix content accompanied by an increase ( p < 0.05) in β-sheet structure when substituting 20–40% back-fat with plant oil combined with pre-emulsification. Pre-emulsification and plant oil substitution changed tryptophan and tyrosine doublet hydrophobic residues in chicken liver paste batters. [ABSTRACT FROM AUTHOR]

The purpose of this study was to evaluate the effects of sugarcane dietary fiber (SDF) and pre-emulsified sesame oil for pork fat replacement on batter characteristics. Replacing pork fat with SDF and pre-emulsified sesame oil significantly affected color, water- and fat-binding properties, texture, dynamic rheology, microstructure and sensory analysis. With SDF and pre-emulsified sesame oil, the batters had improved textures and gave good sensory scores. These batters containing SDF had reduced the cholesterol and fat contents. With increasing levels of SDF, the batters had higher water- and fat-binding properties, improved texture (hardness, gumminess and chewiness), dynamic rheology and a more balanced nutritional composition. However, when the level of SDF reached 3%, the pores formed by SDF in batter were too large to hinder aggregation and the hardness of batter was unacceptable, which result the allover acceptability to be unsatisfactory. The sample 2% SDF had comparable overall acceptability to the control batter. [ABSTRACT FROM AUTHOR]

This study investigated the use of high pressure processing (HPP) for enhancing the functional properties of reduced-fat (20%) and reduced-salt (1%) sausages without the need for additives. The effects of different HPP treatments (100 to 400 MPa) at 10 °C for 2 min on cooking losses, color, textural properties, salt solubility of myofibrillar proteins, rheological properties and microstructure of pork sausage emulsions were compared with the Control (0.1 MPa). The results showed that HPP contributed to a decrease in cooking losses as well as altered color and enhanced textural properties, and also decreased the protein solubility of myosin and actin. Pressure increased G′, G″ and tan δ, and formed a more regular and filamentous microstructure, especially at 200 MPa. In addition, the sensory evaluation exhibited that there was no significant difference between the commercialized emulsion-type sausages and the 200 MPa pressure treated sausages with 20% fat and 1% salt. It was concluded that HPP significantly improved the functional properties of reduced-fat and reduced-salt pork sausages, and the optimum conditions was 200 MPa at 10 °C for 2 min. Industrial relevance For health reasons, there is a need to reduce fat and salt contents of processed meat products. Using HPP (especially 200 MPa), a meat emulsion-type product with low fat and salt was successfully produced, which retains its expected functional quality attributed of objective texture, color and rheological property, etc. Importantly this is achieved with a marked reduction in cooking loss when cooked thus providing the manufacturer with greater product yield. [ABSTRACT FROM AUTHOR]

High pressure processing (HPP) was used to explore novel methods for modifying the textural properties of pork sausages with reduced-salt, reduced-fat and no fat replacement additions. A 2 × 7 factorial design was set up, incorporating two pressure levels (0.1 or 200 MPa) and seven fat levels (0, 5, 10, 15, 20, 25 and 30%). Sausages treated at 200 MPa exhibited improved tenderness at all fat levels compared with 0.1 MPa treated samples, and the shear force of sausages treated at 200 MPa with 15 or 20% fat content was similar to the 0.1 MPa treated sausages with 30% fat. HPP significantly changed the P 2 peak ratio of the four water components in raw sausages, resulting in improved textural properties of emulsion-type sausages with reduced-fat and reduced-salt. Significant correlations were found between pH, color, shear force and water proportions. The scanning and transmission micrographs revealed the formation of smaller fat globules and an improved network structure in the pressure treated sausages. In conclusion, there is potential to manufacture sausages with reduced-fat and reduced-salt by using HPP to maintain textural qualities. [ABSTRACT FROM AUTHOR]

The objective of this study was to track the changes and the relationship between structure and functional properties of rabbit myosin during heat-induced gelation, and to provide more insight into the gelation properties of rabbit myosin. Storage modulus (G′) and loss modulus (G′′) during the heat-induced gelation process were measured by a rheometer, and the water holding capacity (WHC) and hardness of the heat-induced gel were measured by centrifugation method and texture analyzer, respectively. The quantitative analysis of secondary structural content was performed by circular dichroism (CD). The CD data were fitted to three secondary structures, which were α-helix, β-sheet, and random coil. The results showed that the WHC, hardness, G′, G′′, β-sheet, and random coil increased with the increase of temperature, while the α-helix decreased. The changes of structural properties of myosin determined the functional properties during the heat-induced gelation process, and they had a very strong correlation. [ABSTRACT FROM AUTHOR]

The changes of water mobility and fractal dimension (Df) during pork myofibrillar proteins (PMP) heat-induced gelation were investigated using low-field nuclear magnetic resonance (NMR) and image analysis, respectively. The NMR data were related to the gel microstructure which was explained as fractal dimension and pore size using principal component analysis (PCA). Distributed exponential analysis of the T2 relaxation revealed that three water components corresponding to the three water molecule states exist during the heat-induced gelation. A significant change of T2 was occurred when the temperature increased, T21 relaxation times decreased significantly from 403.70ms to 231.01ms with the temperature increasing from 50 to 70°C. The fraction of T21 distributions declined from 99.27% to 77.01% as the temperature increased from 40 to 60°C. Pronounced different gel network structure was observed during the myofibrillar proteins heat-induced gelation and different Df which was determined by box count method was found between all treatments although evidencing a narrow scale range (from 2.835 to 2.860). Good correlations were detected between the NMR T2 parameters and microstructural data. Overall, combined low-field NMR, image analysis and PCA provide powerful tools for elucidating the pork myofibrillar protein heat-induced gelation. [ABSTRACT FROM AUTHOR]

Model heat-induced gels were prepared. Compared with the broiler myofibrillar protein ( BMP), interactions between porcine plasma protein ( PPP) and spent-hen myofibrillar protein ( SHMP) were evaluated using rheology, textural analysis, nuclear magnetic resonance and scanning electron microscopy ( SEM). The gel hardness of SHMP was higher than that of BMP. PPP had the highest stickiness and immobilized water fraction of all the gels. The plasma and broiler myofibrillar mixed proteins had a storage modulus similar to that of BMP. After mixing SHMP or BMP with PPP, immobilized water fraction was increased by 5.59% or 50.57%, respectively, and the water-holding capacity ( WHC) of the latter significantly increased. Addition of PPP transformed SHMP heat-induced gel to a uniform interconnected network. Introducing PPP can improve the WHC and microstructure of SHMP and BMP gels. Practical Applications Spent-hen meat is an underutilized raw material which could be used for mince or imitation products. However, there lies diversity on heat-induced gel properties among different researches. As incorporation of spent-hen breast surimi into analog food can bring worse quality, such as increases of cooking losses and decreases of water-holding capacity, it is the valuable trying to improve quality through protein interaction. This research could be useful to the modification of mince or imitation products with spent-hen meat, and to the manipulation of texture and water-holding capacity of meat products with plasma protein. [ABSTRACT FROM AUTHOR]

Abstract: The effects of microbial transglutaminase (MTG) on heat-induced gelation of pork myofibrillar proteins (PMP) structural changes, textural properties were studied by Raman spectroscopy and texture profile analysis (TPA), respectively. And the relationships between the structural changes and textural characteristics were estimated by principal component analysis (PCA). Changes in the Raman spectra were interpreted as the occurrence of secondary structural changes in myofibrillar proteins with MTG added. Modifications in the amide I (1600–1700cm−1) regions indicated a significant (p<0.05) decrease in α-helix content, accompanied by a significant (p<0.05) increase in β-sheets, β-turns and random coil content due to the addition of the enzyme. Obvious texture property changes were also determined by TPA. All these changes showed a strong, irreversible heat-induced gel formed due to the addition of MTG. The application of a dimensionality reducing technique such as PCA proved to be useful to determine the most influential properties of heat-induced gel. Significant (p<0.05) correlations were found between these structural changes and the textural characteristics (hardness) in PMP system with the addition of MTG by PCA. The hardness was related positively to fraction of β-sheet, β-turns and random coil, and negatively to normalized intensity of 760cm−1 and fraction of α-helix. The samples are closely grouped in a cluster defined by level of MTG. [Copyright &y& Elsevier]

[Display omitted] • Polyphenols were able to covalently bond with glycated myofibrillar protein (MP). • Physicochemical properties of ternary conjugates depended on nature of polyphenols. • Adducted polyphenols altered the conformation characteristics of glycated MP. • MP-dextran (DX)-polyphenol ternary adducts had higher thermal stability. • MP-DX-polyphenol ternary adducts had higher antioxidative capacity. In the present study, three types of polyphenols, namely, (−)-epigallocatechin-3-gallate (EGCG), catechin (C), and gallic acid (GA), were grafted to myofibrillar protein (MP)-dextran (DX) conjugate through a free radical-mediated adduction method. The analysis of secondary structure showed that conjugation of polyphenols induced a decrease in contents of α-helix structures. The surface hydrophobicity of MP-DX conjugate was increased after polyphenols were covalently adducted, while that of the free amino, thiol groups, and tyrosine residues were decreased, especially with the addition of EGCG (p < 0.05). Analysis of rheological properties showed that covalently linking of polyphenols decreased the thermal gelling capacity by inhibiting myosin-head aggregation and myosin tails interaction. Moreover, polyphenol adduction was able to remarkably improve the thermal stability and antioxidant activity of MP-DX conjugate. The findings regarding enhanced functionalities evidence potential of applying the ternary adduct as a novel antioxidant. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Myofibrillar proteins (MPs) of chicken breast are generally insoluble in water. We have developed a new method whereby MPs are solubilized in water by applying high-pressure homogenization (HPH) thus potentially enabling greater utilization of meat in various products. To clarify the mechanism of solubilization of MPs by HPH, we investigated their conformation, solubility and filament forming behavior in low ionic strength solutions induced by 15,000 psi HPH (103 MPa). HPH induces unfolding of MPs which subsequently exposes sulfhydryl and hydrophobic groups to the surface. Our findings, determined by circular dichroism, ATR-FTIR, SDS-PAGE and LC-ESI-MS/MS analysis suggest that HPH leads to unraveling of helical structures and to formation of myosin oligomers through disulfide bond. Due to intermolecular electrostatic repulsion and physical barrier of disulfide bonds in the rod induced by HPH, we suggest that the altered myosin conformation in MPs inhibits filament formation, thus contributing to high solubility of MPs in water. [ABSTRACT FROM AUTHOR]

The effects of different size particles and contents of sugarcane dietary fiber(SDF) on water state, water holding capacity(WHC), gel strength and microstructure of myofibrillar protein gels was studied. It was found that gel strengths were improved with the increase in SDF particle size and content, and the value of water holding capacity (WHC) reached a maximum with the addition of 80-mesh SDF at 2%. Discrete exponential fitting analysis and multi-exponential function analysis of the T 2 relaxation time revealed that three categories of water, each having different mobility states in the gels, had different effects on the blended gel systems. Also, the intrinsic T 21 relaxation time of immobile water in gels containing SDF was shorter than that in pure gels. Pronounced differences in myofibrillar gel network structures were observed during heating at 80 °C for 20 min. The fractal dimension which was determined by the box count method and the pore density (diameter < 0.1 μm or < 1 μm) further demonstrated that the homogeneity and compactness of gels increased with higher SDF content. However, the formation of numerous SDF cavities, whose particle size and number was enormously affected by the particle size and ratio of SDF added, is likely to have been responsible for the decrease in WHC and the extension of the intrinsic T 21 relaxation times of immobilized water. [ABSTRACT FROM AUTHOR]

Effects of water-misting sprays with forced ventilation on post mortem glycolysis, adenosine monophosphate-activated protein kinase (AMPK) and meat quality of broilers after transport during summer were investigated in the present paper. A total of 105 mixed-sex Arbor Acres broilers were divided into three treatment groups: (i) 45 min transport without rest (T); (ii) 45 min transport with 1 h rest (TR); and (iii) 45 min transport with 15 min water-misting sprays with forced ventilation and 45 min rest (TWFR). Each treatment consisted of five replicates with seven birds each. The results indicated that the water-misting sprays with forced ventilation could mitigate the stress caused by transport under high temperature conditions during summer, which reduced the energy depletion in post mortem Pectoralis major (PM) muscle. This resulted in a higher energy status compared to the T group, which would decrease the expression of phosphorylation of AMPK (p-AMPK). Furthermore, decreased the expression of p-AMPK then slowed down the rate of glycolysis in post mortem PM muscle during the early post mortem period, which in turn lessened the negative effects caused by transport on meat quality. In conclusion, water-misting sprays with forced ventilation may be a better method to control the incidence of the pale, soft and exudative meat in broilers. [ABSTRACT FROM AUTHOR]

Myosin, a major muscle protein, can be solubilised in a low ionic strength solution containing l -histidine (His). To elucidate which chemical constituents in His are responsible for this solubilisation, we investigated the effects of 5 mM His, imidazole (Imi), l -α-alanine (Ala), 1-methyl- l -histidine (M-his) and l -carnosine (Car) on particle properties of myosin suspensions and conformational characteristics of soluble myosin at low ionic strength (1 mM KCl, pH 7.5). His, Imi and Car, each containing an imidazole ring, were able to induce a myosin suspension, which had small particle size species and high absolute zeta potential, thus increasing the solubility of myosin. His, Imi and Car affected the tertiary structure and decreased the α-helix content of soluble myosin. Therefore, the imidazole ring of His appeared to be the significant chemical constituent in solubilising myosin at low ionic strength solution, presumably by affecting its secondary structure. [ABSTRACT FROM AUTHOR]

This study optimized the high pressure conditions for development of a reduced fat sausage. A three-factor-three-level Box–Behnken design was adopted to study the simultaneous effects of one compositional variable (15, 20 and 25% fat content) and two processing variables (150, 200 and 250 MPa high pressure, along with 5, 6 and 7 min high pressure treatment time) on firmness of emulsion-type sausages. Analysis of variance (ANOVA) was performed to evaluate the potential interactive and quadratic effects between these variables. The results revealed that, the optimum processing conditions for an optimum gel setting were 22.19% fat content, 197.30 MPa high pressure and 5.92 min pressure treatment time. The adequacy of the model equation for predicting the optimum response values was effectively verified. In conclusion, the emulsion-type meat sausages using a novel high pressure based processing method were preferred for their improved textural properties and reduced fat content. Industrial relevance For health reasons, there is a need to reduce fat content of processed meat products. This study developed a novel processing method using high pressure to produce emulsion-type meat sausages with reduced-fat, with improved functional qualities, including objective appearance, textural properties and sensory evaluation. Importantly, this was achieved with a model, mainly based on prediction of the firmness of the pressure treated sausages with reduced fat contents. [ABSTRACT FROM AUTHOR]

The effects of pressure/thermal combination treatments, i.e. heating before pressure treatment (H-P), pressure treatment before heating (P-H), and heating under pressure (P + H), on chicken batters were investigated using heating (H) as control. The appearance, texture, water holding capacity (WHC), water mobility and distribution, and microstructure were determined. P + H and P-H treatments promoted the batter gelation process, forming a gel with fine strands which resulted in improved appearance, texture and water holding capacity, while H-P treatment, with a similar coarse gel network to H treatment, showed little improvement in texture and appearance, but had increased released water and centrifugation loss. By treating with 200 MPa at 75 °C for 30 min in a single-step process, the chicken sausage had the smoothest appearance, lowest released water and an improved texture. The water mobility and distribution were studied by low-field NMR relaxometry, which showed that H-P and P + H treatment increased the proportion of immobilized water as indicated by T 21 relaxation times and population (P 21 ). Microstructure further explained the quality improvement of P-H and P + H treatment which could be ascribed to the pressure effects before/during protein denaturation promoting formation of a fine gel network, while H-P treatment limited the resulting effects of pressure on the cooked sample. Hence, P-H and P + H treatment can be used to improve the texture and WHC of gel-type meat products. Industrial relevance Temperature and pressure are two important thermodynamic parameters which can be combined in several ways in meat product processing. The sequence of pressure and thermal treatment has a significant effect on the quality of meat products. This information will help meat industry to adopt suitable pressure/thermal treatment to produce meat products. [ABSTRACT FROM AUTHOR]

The impact of various field strength (2, 3, 4 kV/cm) and treatment time (60s and 90s) combinations on NaCl content and diffusion coefficient of beef were evaluated in the current study. Weight change, water content, water holding capacity, and texture of beef after brining were also explored. The results demonstrated pulsed electric field (PEF) pre-treatment significantly increased NaCl uptake when the brining time was 150 min (P < 0.05). The maximum NaCl content increased by 19.50% and the diffusion coefficient increased by 58.50%. Relatively mild PEF (60s) could improve beef qualities, but longer treatment time (90s) was detrimental to these qualities. Meanwhile, more complete myofibrillar structure and lower lipid oxidation extent were observed in the samples treated by PEF, contributing to the higher a* values. In conclusion, short processing time (60s) and high field strength (4 kV/cm) treatment is a potential strategy for meat brining acceleration and quality improvement in practical industrial production. • Impact of different field strength and pulse number (treatment time in current research) combination on salt content and qualities of cured beef were investigated. • Fitting model of beef curing progress was established. • Beef treated with 2 kV/cm and 4 kV/cm showed a higher NaCl content and quality attributes, while the specific field strength of 3 kV/cm negatively influenced qualities like tenderness and hardness. • Short treatment time (60s, 2475 pulses) seems to be a better choice in industrial production. [ABSTRACT FROM AUTHOR]

In order to better showcase the freshness of fresh meat, merchants usually place absorbent pads under tray packaging for preservation. However, the current absorbent pads can only absorb a small amount of blood water and cannot effectively inhibit the growth and reproduction of microorganisms in tray packaging. Herein, a super absorbent aerogel pad for preserving fresh meat was prepared through the Schiff base reaction. Benefiting from the superhydrophilicity and porous structure of aerogels, the prepared G3D1BC0.5 (Gelatin: Dialdehyde starch = 3:1, Bacterial cellulose: 0.5%) aerogel not only possessed excellent adsorption performance but also rapidly regain their shape under 70% compression strain. The G3D1BC0.5 aerogel incorporating curcumin (Cur) showed the good antibacterial ability where the survival rate of Listeria monocytogenes , Staphylococcus aureus , Escherichia coli and Salmonella typhimurium significantly decreased to lower than 45% with the increase of Cur content (P < 0.05). Furthermore, the prepared aerogels had the excellent preservation effect on fresh meat during storage. The G3D1BC0.5-Cur0.7 aerogels can extend the shelf-life of fresh pork to 12 days by inhibiting microbial growth, protein oxidation, and lipid oxidation. Therefore, the prepared aerogel in the present study had great potential for preservation of fresh pork. [Display omitted] • Development of superabsorbent aerogel is based on Schiff base reaction. • Bacterial cellulose significantly improves the performance of aerogel. • The prepared superabsorbent aerogel can release curcumin to inhibit bacteria. • Superabsorbent antibacterial aerogel extends the shelf life of fresh pork to 12 d. [ABSTRACT FROM AUTHOR]

High hydrostatic pressure (HHP) treatment (< 200 MPa) has been known to increase the emulsification properties of myosin. However, the relationship between interfacial elasticity and emulsion stability is complicated. Therefore, this study was focused on exploring the effects of high hydrostatic pressure on the physiochemical and structural properties of interfacial proteins within a stabilized oil-in-water (O/W) rabbit myosin emulsion. We analyzed the adsorption rate and structure of interfacial proteins pressurized under 0.1 [control], 100, 150, and 200 MPa prior to emulsion preparation. As the pressure was increased from 0.1 to 150 MPa, the adsorption rate of interfacial protein increased. HHP treatment caused myosin to unfold, which enhanced the exposure of reactive sulfhydryl and hydrophobic groups. Furthermore, the frequency of hydrogen bonding and hydrophobic interactions increased. As hydrogen bonding increased, the secondary structure of myosin became more stable. As the pressure increased to 200 MPa, the interfacial myosin aggregated, displaying a decreased surface hydrophobicity and reactive sulfhydryl groups (P < 0.05) and thus the emulsion stability decreased. In conclusion, HHP treatment of myosin at 150 MPa significantly improved the stability of the myosin emulsion. Myosin is an important protein in meat and its emulsion stability can be enhanced by HHP. This study reveals the conformational mechanism by which HHP improves the stability of myosin emulsions, providing potential theoretical basis for the application of HHP treatment to improve the quality of emulsified meat products as a non-thermal processing technology in the practical production. [Display omitted] • Moderate HHP promoted the unfolding of myosin and its interfacial adsorption. • 150 MPa optimally increased surface hydrophobicity and reactive SH groups content. • 150 MPa optimally enhanced the hydrogen bonding and hydrophobic interaction. • Excessive HHP led to myosin aggregation and impeded myosin adsorption. [ABSTRACT FROM AUTHOR]

The incidence of pale, soft, and exudative (PSE)-like chicken meat is high worldwide. PSE-like chicken meat seriously affects the sensory qualities of fresh meat, which can decrease the consumer's purchasing desire, reduce chicken meat functionality, and decrease product yield, resulting in extensive economic losses for the poultry processing industry. This meat defect has been of increasing concern to processors and researchers in the poultry processing industry. The processing properties of PSE-like meat and the methods for improving its processing properties or alleviating its reduced functionalities are reviewed in the present article, with the aim of providing a theoretical basis and technical support for poultry processing to increase the practical value of PSE-like chicken meat. [ABSTRACT FROM AUTHOR]

Abstract High pressure homogenization (HPH) can solubilize myofibrillar proteins (MPs) in water. To elucidate the effect of the HPH disruption chamber geometry on the physicochemical and structural properties of MPs in water, two types of nozzle and a counter flow interaction chamber (cf) were applied to homogenize MPs aqueous solutions at pressures of 0 MPa, 103 MPa and 172 MPa HPH for 2 passes, and the physical dispersion and conformational characteristics of MPs in water were investigated. The nozzles and counter flow chamber played a major role in the solubility of MPs in water at 103 MPa and 172 MPa HPH, respectively. Turbulence and cavitation in a narrow nozzle and counter flow action resulted in a decreased MP particle size (232 nm) in water, destroyed secondary structures and exposed hydrophobic and SH groups. The solubility (98.1%) and stability of MPs in water were increased by HPH. The results showed that the required solubility of MPs in water can be achieved by adopting proper HPH disruption chamber geometry , which provides a new method on meat processing. Highlights • High pressure homogenization (HPH) solubilized myofibrillar proteins (MPs) in water. • HPH at 172 MPa induced a better solubility and stability of MPs in water. • The bore diameter of nozzle played a major role at 103 MPa HPH. • At 172 MPa HPH, the counter flow interaction chamber was dominant. [ABSTRACT FROM AUTHOR]

Abstract Structural changes and emulsion properties of proteins extracted by acid processes (ACP, pH 2.0, 2.5 and 3.0) and alkaline processes (ALP, pH 11.0, 11.5 and 12.0) were evaluated, with non-treated goose-liver (GL) paste set as the control. Increasing contents of either reactive-sulfhydryl or surface hydrophobic groups were observed in isoelectric solubilisation/precipitation-recovered proteins (P < 0.05). The ACP-proteins showed higher surface hydrophobicity but lower reactive-sulfhydryl content than that of ALP-proteins (P < 0.05). Compared to the control, ACP-proteins had lower α-helix and β-sheet contents (P < 0.05); meanwhile, ALP-proteins exhibited a lower α-helix content but higher β-sheet content (P < 0.05). Tentative application of these recovered proteins as emulsifiers exhibited that proteins underwent treatment at pH 11.0 had a higher emulsifying activity index (3.2 mg/m2), emulsifying stability index (17.2%) and emulsifying viscosity (62 Pa s) than that of the control (P < 0.05), along with smaller and spherical droplets uniformly distributed in the emulsion. However, ACP-protein emulsions exhibited adverse trends. Different secondary structures of the proteins in ACP-/ALP-cream layers explained these divergences in part, where the lower β-sheet content of ACP-samples could impair protein interactions, leading to inferior emulsion properties. In contrast, the increased β-sheet fraction of alkali treatment favoured a more stable emulsion. Potential of ALP-proteins as an emulsifier was verified. Highlights • Isoelectric solubilisation/precipitation (ISP)was used to obtain goose liver protein. • Acidic or alkali ISP-extracted proteins were found differ in physicochemical traits. • Alkali-ISP obtained proteins showed better emulsion traits than acidic counterparts. • Higher α-helix in alkali-samples partly explained better emulsion ability & property. • Proteins recovered at pH 11.0 ISP-process was the most potential sample as emulsifier. [ABSTRACT FROM AUTHOR]

Abstract The effects of insoluble dietary fiber (IDF) on myofibrillar protein (MP) emulsion gelations were investigated through a model system. Steady shear tests indicated an increase of molecular interaction/friction in composite solutions with IDF inclusion. It was noted that IDF addition prevented oil dispersion and resulted in the average enlargement oil globules volume diameter (d 4,3) from 145.25 (control) to 200 μm (2% IDF), in emulsified systems. In dynamic rheology, the final G′ of the emulsion gelations significantly increased from 203 (control) to 462 Pa (2% IDF), while the T 21 relaxation time of immobilized water, in emulsion gels containing 2% IDF (202.44 ms), was significantly shorter than in control gels (244.25 ms). In addition, the water- and fat-binding capabilities, and the gel strength of emulsion gelations, significantly increased with IDF addition. The aforementioned results indicate that IDF addition could promote the formation of a stronger gel network. As a result, the MP gel microstructure was further studied. The MP gel microstructure of gels containing IDF had reduced formation of interconnected water with a gel network possessing more integrity and overall compactness, especially 2% IDF addition. In conclusion, IDF addition was shown to play an important role in the physicochemical properties of low-fat emulsion gels through the enlargement of oil particle size and through the modification of the overall MP gel network. Highlights • IDF addition significantly improved the gel strength and WBF of MP gelation. • IDF addition increased intermolecular interaction/friction in MP sol. • The "concentrated" MP promoted to form compact and homogeneous gel network. [ABSTRACT FROM AUTHOR]

Highlights • Low-frequency magnetic field influenced on myofibrillar protein gel properties. • 0.5 mT was the optimum intensity for water-holding capacity of gel. • Low-frequency magnetic field affected secondary structures of myofibrillar protein. Abstract This study aimed to investigate the effect of a low-frequency magnetic field (LF-MF; 0, 0.25, 0.5, and 1.4 mT) on the gel properties of pork myofibrillar protein (MP) and to explore potential mechanisms. The water-holding capacity (WHC) and rheological properties of MP gels treated at 0.5 mT were better than those from other treatments. The water mobility did not change significantly as intensity increased, while the ratios of immobilized water (PT 21) and free water (PT 22) significantly decreased and increased, respectively. This suggested that the effect of LF-MF on MP hydration might be related to the formation of water clusters. Raman spectra suggested that α-helices unfolded and β-sheets, β-turns, and random coils were formed in MP gels (from 0.25 to 1.4 mT). Furthermore, the intensities of characteristic peaks in the tryptophan and aliphatic residues band were highest at 0.5 mT, indicating that 0.5 mT was the optimum intensity for hydrophobic interactions. [ABSTRACT FROM AUTHOR]

Abstract A low-cost, convenient and organic solvent-free approach was investigated to nanoencapsulate curcumin (CCM) in myofibrillar proteins (MPs) as a potential strategy to improve the oxidative stability of marinated meat products. The encapsulation was enabled by shifting CCM–MP mixture to pH 12 and then pH 7 at different ionic strengths. Stable CCM–MP nanocomplexes were formed at 0.3, 0.6 and 0.9 mol/L NaCl, resulting from the exposure of hydrophobic residues of MPs at alkaline pH to bind with dissolved CCM, which enabled an encapsulation efficiency of about 80% and particle diameters of about 300 nm. DPPH and ABTS radical scavenging tests showed good antioxidant activity of CCM–MP nanocomplexes that enabled the reduction of TBARS and carbonyls values of both raw and cooked chicken meat during refrigerated storage for 12 days. Overall, the stable CCM–MP nanocomplexes show the potential applications to manufacture functional meat products with improved quality. Highlights • MPs can be used as a novel carrier to encapsulate CCM by pH shifting method. • The solubility and bioavailability of CCM were improved after encapsulating in MPs. • Stable CCM–MP nanocomplexes were formed at ionic strength of 0.3, 0.6 and 0.9 mol/L. • CCM–MP nanocomplexes could protect chicken meat from oxidation during storage. [ABSTRACT FROM AUTHOR]

Protein glycosylation results in structural changes which affects its functionalities. In this study, myofibrillar protein (MP) from pale, soft and exudative (PSE)-like chicken breast meat was grafted onto the glucosamine (GlcN) backbone using microbial transglutaminase (MTGase) as a biocatalyst and the impacts of glycosylation on structural and solubility properties of the conjugation product were investigated. The covalent attachment was verified by HPLC and Fourier transform infrared spectroscopy (FT-IR). The optimal conjugation conditions were 37 °C at pH 7.5 for 6 h with a MP to GlcN weight ratio of 1:3. The results of secondary structure analysis suggested that the glycosylated MP had decreased α-helix level and increased β-sheet, β-turns and random coil levels. After glycosylated with GlcN, the surface hydrophobicity was significantly reduced and the solubility of MP at the isoelectric point was markedly improved ( P  < 0.05). Overall, the information obtained from this study can enrich the theoretical frame of enzymatic glycosylation. Additionally, these results suggest that enzymatic glycosylation is a promising approach for improving the solubility of MP from PSE-like chicken breast meat for food applications. [ABSTRACT FROM AUTHOR]

Summary: The potential of nonenzymatic glycation of myofibrillar proteins (MPs) to improve the gelation functionalities of pale, soft and exudative (PSE‐like) chicken breast meat was investigated. MP suspensions (4 mg mL−1) obtained from both normal and PSE‐like chicken breast meat were mixed with glucosamine at a ratio of 1:6 (protein : glucosamine) in phosphate‐buffered saline (0.6  m KCl, 20 m m K2HPO4/KH2PO4, 0.02% NaN3 and pH 7.5) and incubated at 37 °C for 12 h. Untreated normal and PSE‐like MP suspensions maintained at 4 °C were used as positive and negative controls, respectively. The glycation treatment increased the surface hydrophobicity but decreased the reactive sulfhydryl contents compared to those of the control (P < 0.05), indicating that the tertiary conformation of the protein changed. Correspondingly, these glycated samples also exhibited significant improvements in gel strength and the water‐holding capacity (P < 0.05). Conclusively, nonenzymatic glycation is a potential technique to improve the properties and offer a means for effective use of PSE‐like meat. [ABSTRACT FROM AUTHOR]

• This study assessed curcumin's effect on polycyclic aromatic hydrocarbons (PAHs). • Curcumin markedly inhibited PAHs (65%–70%) in pre-marination of chicken wings. • PAHs were suppressed by reduction of fat oxidation and free radical contents. Organic macromolecules form carcinogenic and toxic substances such as polycyclic aromatic hydrocarbons (PAHs) under high temperature baking. Thus, this study investigated the effects and inhibition pathways of different curcumin concentrations (0.01, 0.05, 0.25, 0.3 mg/g) on seven PAHs in grilled chicken wings. The results demonstrated that curcumin concentrations displayed positive effects in inhibiting the formation of PAHs (16%–72%), increasing the total phenolic content (397.5–1934.4 mg/g) and free radical scavenging activity, and reducing TBARS values (31.15%–47.76%) and fatty acid content. Additionally, PCA and Pearson correlation analyses indicated that lipid oxidation (r = 0.42) and unsaturated fatty acids (r = 0.55) could promote the production of PAHs, while DPPH, ABTS and TPC could counteract their facilitation of PAHs. In conclusion, the addition of appropriate amounts of curcumin before grilling is a feasible strategy to reduce fat oxidation levels and the number of free radicals for the purpose of limiting PAHs content. [ABSTRACT FROM AUTHOR]

For greater utilization of meat as a source of high-quality protein supplements, we investigated the effects of heating (30–80 °C) on the solubility, rheological behavior, conformational changes and interactions of water-soluble chicken breast myofibrillar protein (WSMP) prepared by high-pressure homogenization (HPH) in comparison with those of salt-soluble myofibrillar protein (SSMP) and HPH-treated SSMP (H-SSMP). Upon heating above 40 °C, WSMP exhibited a shear-thinning behavior with relatively high solubility and flow ability. The thermal gelling ability appeared to be impaired, probably due to weak myosin-head aggregation (30–50 °C) and less interaction between myosin tails (70 °C). WSMP was less prone to unfolding during heating and resulted in smaller protein aggregates in comparison to SSMP and H-SSMP. Moreover, the lower extent of thermally induced disulfide cross-links and hydrophobic and electrostatic interactions led to improved colloidal stability in WSMP. The enhanced solubility and flow ability of WSMP after heating are beneficial to the development of new meat-based products. [ABSTRACT FROM AUTHOR]

Summary: Isoelectric solubilisation/precipitation (ISP) process was applied to goose liver (GL) for protein extraction. The gelation properties of proteins extracted by acid processes (ACP, pH 2.0, 2.5 and 3.0) and alkaline processes (ALP, pH 11.0, 11.5 and 12.0) were estimated, where the unextracted ground GL was set as the control. Nearly 58.39~79.00% of GL proteins were recovered by ISP treatments. High molecular weight (100~250 kDa) proteins were found to be partially hydrolysed by ACP, while few changes in proteins occurred during ALP. As evidenced by rheological and textural measurements, ALP proteins formed gels with high elasticity and superior texture, whereas ACP proteins had inferior gelation properties. Moreover, ALP proteins were able to form a highly interconnected and homogeneous three‐dimensional microstructure. Predominantly, gels produced by 11.0 had optimal texture and the lowest cooking loss (P < 0.05). These results suggested that the ISP process (ALP) is a potential method to improve the economic value of GL. [ABSTRACT FROM AUTHOR]

To investigate the effects of pre-oxidized myofibrillar protein (MP) on stability of heat-induced MP gelation throughout 28 days of refrigeration, a hydroxyl radical generating system (10 μM FeCl3, 0.1 mM ascorbic acid, with 10 mM H2O2) was employed. Results demonstrated that an increase of carbonyl content followed a similar trend in both pre-oxidized and non-oxidized protein gels. Unexpectedly, pre-oxidized protein gels yielded increased (P < 0.05) hardness at 14 days of storage compared to the initial day of storage. The water holding capacity (WHC) had a significant positive correlation with gel hardness, percentage of immobile water, and T22, while having a negative correlation with carbonyl group content and T23 (P < 0.01). These results suggest that the pre-oxidation treatment increases the susceptibility of MP gel matrices to undergo oxidation and thus provides a better comprehension of the consequences that in vitro pre-oxidation treatments have on protein matrix systems. [ABSTRACT FROM AUTHOR]

The effects of sugarcane dietary fiber (SDF) on the gelation properties of porcine myofibrillar proteins (MP) were studied to understand its mechanism of action in improving gel functionality. Rheological tests on all composite gels (MP with SDF) showed the visco-elastic nature of MP, but the G′ significantly increased with contents of SDF and with particle size ( P < 0.05). However, the δ exhibited the opposite effect. Light microscopy suggested that SDF affected moisture distribution in the gel by drawing water from MP and homogenously embedded in gelation. It is proposed that during the heating the more concentrated MP promoted the unfolding of MP chains and facilitated the formation of β-sheet instead of α-helices, leading to a compact and homogenous three-dimensioned network. These results indicated that the SDF changed the water distribution and resulted in the enhanced gelation which reacted to firmly bind SDF and form a synergistic interaction system. [ABSTRACT FROM AUTHOR]

Changes in protein intermolecular interactions during thermo-gelling were measured to compare the gelation properties of isoelectric solubilization/precipitation (ISP)-isolated protein extracted (solubilized at 3.5 and 11.0, precipitated at 5.5 and 6.2) from pale, soft, and exudative (PSE)-like chicken breast meat with raw meat paste. The solubility of both in water and salt (0.6 M NaCl) decreased significantly after ISP treatments. Protein profile analysis revealed that precipitation pH showed little influence on protein profile. Under pH 3.5 and pH 11.0 solubility conditions, the recovered protein at pH 6.2 showed significantly higher gel hardness than that at pH 5.5, which can be induced by hydrophobic change. Surface hydrophobicity (SH) and hydrophobic interactions at 25 °C presented similar results, indicating that the soluble protein at pH 11.0 exhibited a higher value after precipitation at pH 6.2 than that at pH 5.5, and the hydrophobicity of pH 3.5 isolates was higher than that of the pH 11.0 groups. However, the maximum hydrophobicity upon heating was inconsistent with initial tendencies. Given that the hydrophobic residues were exposed sufficiently during the ISP process, the ISP-treated proteins, particularly the samples extracted at pH 3.5, might be less susceptible to heat-induced exposure. The gelation behavior of the ISP-treated proteins had been modified on the basis of the intermolecular bonds during heating. In conclusion, the precipitation condition demonstrated excellent relevance for product development based on functionality. [ABSTRACT FROM AUTHOR]

This study investigated the role of high-pressure processing (HPP) for improving the functional properties of meat batters and the textural properties of reduced-fat sausages. Application of 200 MPa pressure at 10 °C for 2 min to pork batters containing various fat contents (0–30%) affected their rheological properties, cooking losses, color, textual properties and their protein imaging. The results revealed that both application of 200 MPa and increasing fat content decreased cooking loss, as well as improved the textural and rheological properties. Cooking losses, texture and sensory evaluation of 200 MPa treated sausages having 20% fat were similar to those of the 0.1 MPa treated sausages having 30% fat. Principal component analysis revealed that certain quality attributes were affected differently by the levels of fat addition and by HPP. These findings indicated the potential of HPP for improving yield and texture of emulsion-type sausages having reduced fat contents. [ABSTRACT FROM AUTHOR]

[Display omitted] •. The interactions between MP and NHDC were limited at 0.2 M NaCl. • The interactions between MP and NHDC were enhanced at 0.6 M NaCl. • High doses of NHDC led to excessive aggregation of MP at 0.6 M NaCl. • High doses of NHDC caused damage to the gelation properties of MP at 0.6 M NaCl. • Interactions between MP and NHDC were hydrogen bonds and hydrophobic interactions. Effects of sweetener neomethyl hesperidin dihydrochalcone (NHDC) on the gelation properties of myofibrillar protein (MP) at 0.2 M and 0.6 M NaCl were investigated. The results showed that addition of NHDC did not obviously change the cooking loss and strength of MP gels at 0.2 M NaCl. Whilst at 0.6 M NaCl, addition of high doses of NHDC (50–100 µM/g) remarkably increased cooking loss and decreased strength of MP gels. The expanded MP enhanced the interactions between NHDC and MP, leading to aggregation of MP as evidenced by the increasing particle size and the reducing solubility. The MP aggregates impeded hydrophobic interactions and disulfide bonds crosslinking in the gelation process, thereby damaged the gelation properties of MP at 0.6 M NaCl. This was supported by the poor network of MP gels observed by SEM. In the end, molecular docking elucidated the main types of interaction at molecular level, including hydrogen bonding and hydrophobicity. The results would provide guidance for NHDC as a potential sweetener in meat products. [ABSTRACT FROM AUTHOR]

• Effect of oxidation on thermal gel formation process of myofibrillar protein was explored. • Degree of protein oxidation had a significant effect on thermal gelation formation. • Oxidation reduces G' during thermal gel formation process of myofibrillar protein. • Oxidation affected water holding capacity by changing immobile and free water amounts. In this study, the effect of protein oxidation on the thermal gelation of chicken breast myofibrillar proteins (MPs) was investigated. MP samples treated with different degrees of oxidation were heated (1.5 °C/min) to different end-point temperatures to simulate the thermal gelation process. The results showed that the water-holding capacity (WHC) significantly decreased with increasing temperature, and higher oxidation degree resulted in worse WHC of heat-induced gel. Compared with high degrees of oxidation, low degrees of MP oxidation reduced the migration of immobile water, inhibited its release as free water, enhanced WHC and favored the formation of β-sheet and β-turn structures. Therefore, low oxidation promoted the formation of β-sheet and β-turn structures to form a better gel microstructure with less formation of free water on the thermal gelation and therefore increased the WHC. High oxidation was just the opposite, and high temperature aggravated this negative effect. [ABSTRACT FROM AUTHOR]

[Display omitted] • Curcumin changed the secondary structure, tertiary structure, and restriction site of MP digestion product. • Curcumin changed the digestive characteristics and antioxidant activity of MP. • Curcumin can induce MP to produce more unique bioactive peptides after digestion. This study aimed to investigate the in vitro digestion of curcumin-myofibrillar protein (MP) complexes characterized by antioxidant activity and structure changes. Curcumin-MP nanocomplexes were prepared by pH-shifting (from 12 to 7) method and then digested in vitro. Results showed that the protein released by dissolved nitrogen and the scavenging rates of DPPH and ABTS free radicals were enhanced significantly by the formation of nanocomplex with curcumin. During simulated digestion, curcumin can reduce the α-helix of protein, along with red shifted and significantly decreased maximum fluorescence intensity. This structural difference may change the restriction sites of MP, resulting in substantial changes in the digested products composition and 11 unique peptides with potential bioactivity appearance in the digested products of curcumin-MP complex. Our finding revealed the Curcumin-MP nanocomplexes has unique protein digestion fate which has potential application on functional enhanced food. [ABSTRACT FROM AUTHOR]

[Display omitted] • As an emerging non-thermal treatment, cold plasma were used to pretreating raw meat to inhibit PAHs formation in grilled beef steak, inhibitory rates ranged from 35%-96%. • The sunflower seed oil slightly inhibited the formation of PAHs, while others promoted the production of PAHs in grilling process. • The inhibition effect on PAH8 of in-package cold plasma pretreatment was positively correlated with nonpolar antiradical activity of the raw meat. In-package cold plasma (ICP) pretreatment is an emerging non-thermal food processing methods. In the current study, ICP on the formation of polycyclic aromatic hydrocarbons (PAHs) in grilled beef steaks with different oils and fats was evaluated, the influence of prolonged storage periods (1 d, 2 d) of raw meat after ICP pretreatment on the PAH inhibitory effect was investigated. The results showed that sunflower seed oil had an inhibitory effect on PAH formation; the groups with ICP pretreatment showed a significant decrease in PAH content (p < 0.05) according to the UHPLC results, inhibitory rates were dependent on the original contents in each group without ICP pretreatment, ranging from 35% to 96%. The optimal condition was grilling immediately after ICP pretreatment, and the results indicated that the nonpolar radical scavenging activity (RSA) of ungrilled meat was negatively correlated with PAH8 contents according the DPPH assay, while ICP pretreatment enhanced the RSA oil of raw meat. [ABSTRACT FROM AUTHOR]

Myosin, a protein originating from muscle, is traditionally used for meat products for its ability to generate emulsions. Small changes in the emulsifying and conformational characteristics of proteins greatly influence the gel-emulsifying meat products. The effect of high hydrostatic pressure (HHP) on the emulsifying behavior of myosin prepared at different pressures (0.1, 100, 150, and 200 MPa) was investigated. The particle size, microstructure, interfacial tension, emulsifying properties, and secondary structure of myosin were analyzed. The results showed that as pressure increased from 0.1 to 150 MPa, the size of oil drops was reduced, the viscoelasticity of interfacial protein film improved, and the emulsifying activity and stability of myosin increased. Meanwhile, as the pressure increased from 0.1 to 150 MPa, the α helix content of the protein decreased significantly (P < 0.05), which was beneficial for the intermolecular interaction between proteins. A further increase in pressure (to 200 MPa) was detrimental to emulsifying activity and stability. As the pressure increased to 200 MPa, the emulsion displayed a decreased interfacial elasticity and increased protein random coil contents, and the particle size noticeably increased (P < 0.05). Therefore, it is concluded that HHP treatment at 150 MPa improves the stability of myosin emulsions. • 1.The high pressure <150 MPa treatment improved emulsifying capacity of myosin. • 2.The high pressure >200 MPa treatment jeopardized emulsifying capacity of myosin. • 3.The high pressure treatment significantly decreased the α helix content of myosin. • 4.The high pressure treatment enhanced the interaction between myosin and oil. [ABSTRACT FROM AUTHOR]

This study investigated the effect of high-pressure processing (HPP) at 100 to 400 MPa for 2 min on the stability of reduced-fat reduced-salt (RFRS) meat batter. Total expressible fluid (TEF) of RFRS batter reached its minimum value at 200 MPa. The results of Raman spectra revealed that α-helix reached its random coils increased as the pressure level was increased, and pressure up to 200 MPa remarkably increased protein unfolding but 400 MPa increased aggregation. Finally, Raman spectra and magnetic resonance imaging (MRI) revealed that 200 MPa significantly increased tryptophan, tyrosine doublet, CH 3 and/or CH stretching and proton intensities related to water and fats; but decreased β structures, S S stretching (475) and (g-g-t or t-g-t, 540), as compared with the control. RFRS batter treated at 200 MPa is beneficial for the meat industry from the technological point of view and for consumers from the health point of view, as the improved emulsion stability contributed by the modified secondary and tertiary structures. • RFRS meat batter was made to prepare health-friendly sausages. • HPP treatment reduced the drip loss problems of RFRS batter. • HPP altered α-helix, β structures, random coils and CH 3 , CH, O H, and S S stretchings. • HPP enhanced proton intensities, H-bonding and protein interactions of RFRS batter. [ABSTRACT FROM AUTHOR]

• Optimized PEF treatment significantly improved the gelation properties of MPs. • PEF-treated MPs contributed to the formation of a uniform and compact gel structure. • PEF treatment significantly changed the water distribution and mobility of MP gels. • MDS showed that PEF treatment could induce beneficial structural modification of MPs. The potential of pulsed electric field (PEF) of different intensities (8, 18, and 28 kV/cm) on the conformation and gelation properties of myofibrillar proteins (MPs) extracted from pale, soft, and exudative-like (PSE-like) chicken meat was investigated. The results showed a positive correlation between gelation properties and PEF intensities in the range of 8–18 kV/cm; however, a further increase in intensity had a negative impact. Optimized PEF treatment (18 kV/cm) was capable of inducing MPs with a relatively small particle size, thus contributing to the production of a more homogeneous gel structure. The water distribution and mobility in the gel system significantly changed with increasing PEF intensities, the proportion of immobilized water (P 21) increased, and that of free water (P 22) decreased. Based on molecular dynamics simulations (MDS), an increasing trend in the number of hydrogen bonds and a reduction in the radius of gyration (Rg) after PEF treatment. [ABSTRACT FROM AUTHOR]

The functional properties of myosin play a key role in the final quality characteristics of meat products. To explore the molecular mechanism of inulin in improving the properties of porcine myosin gel, different inulin concentrations (0%, 1%, 2%, 3%, 4%, and 5%) were added, and the gel water-holding capacity (WHC), microstructure, rheological properties, secondary structure, surface hydrophobicity and reactive sulfhydryl (R-SH) contents were determined. The results showed that the inulin concentration was in the range of 0%–5%, there was a positive correlation with the gel strength, the storage modulus (G′) and loss modulus (G″) of myosin also gradually increased with the increased of inulin concentration. The addition of inulin improved the WHC of myosin gel which was attributed to the formation of a fine microstructure, when the inulin concentration was 2%, the most significant improvement was observed. The improvement in the properties of heat-induced myosin gelation was due to the change in the molecular structure of myosin after the addition of inulin; the addition of inulin led to the transformation of the secondary structure of myosin, which resulted in the exposure of more hydrophobic groups and sulfhydryl groups than in the control and was conducive to the formation of a heat-induced dense myosin gel network. The principal component analysis results revealed the correlation between the gel properties and the molecular structure and provide a powerful tool for analysis. In conclusion, the addition of inulin can improve the functional properties of myosin and facilitate the heat-induced gelation of myosin. Image 1 • Inulin interacts with muscle protein as a fat substitute. • Inulin improves gel properties of myosin. • The addition of inulin at 2% can significantly affect the molecular structure of myosin. • Inulin can guide the use of fat substitutes in meat products. [ABSTRACT FROM AUTHOR]

Functionalities of muscle protein are vital in the qualitative characteristics of final products. Glycation was explored as a promising way for upgrading the functionalities of muscle protein. Myofibrillar protein (MP) was conjugated with dextran (DX) in a liquid solution at a moderate temperature (37 °C). The conjugation was verified by UV–Vis spectrometry and electrophoresis analysis. The results suggested that glycation affected the particle size and morphology of MP, and glycation induced unfolding of the MP and loss of α-helix structures. As the molecular weight of DX was increased, the glycated MP displayed shear-thinning behavior with better flow ability and higher solubility, and the solubility at isoelectric point was noticeably improved (P < 0.05). The thermal gelling ability seemed to be impaired, probably because glycation exerted a protective effect on MP by inhibiting aggregation during heat-induced gelation. The results provide a further understanding of the relationship between the structure and functionalities of glycated MP, which can be utilized as a new additive. Image 1 • Glycation induced conformation changes of myofibrillar protein (MP). • Conjugated with 70 kDa dextran (DX) improved the solubility of MP more effectively. • Introduction of DX increased the flow ability of MP. • Thermal gelling of glycated MP appeared to be inhibited. [ABSTRACT FROM AUTHOR]

• Proteomics found high-pressure treatment (HPT) altered structural proteins at large. • In vitro gastric and intestine digestibilities of meat protein were improved by HPT. • Mutual peptides in the final digesta showed HPT-specific patterns. • HPT is assumed to expose the protein digestive sites thus improving digestibility. Effects of high-pressure treatments (HPT, 100–300 MPa, 9 min, 25 °C) on the in vitro digestibility of gel-type meat products were studied using a simulated digestion-model. In vitro digestibilities of the cooked rabbit meat batters throughout the simulated oral-, gastric-, and intestinal-phases were determined. Peptides in the intestinal digesta were identified via Mass Spectrometer. Results revealed that in vitro digestibilities of HPT-samples were higher than the control (1.98%, 6.13% and 61.31% for oral-, gastric- and intestinal-phase respectively) throughout the digestion (P < 0.05). Alterations of the peptide profiles were induced by HPT, showing HPT-specific patterns of mutual peptides in the digestive products. Coupled with the identifications of salt-soluble proteins from raw batters, it was confirmed that myofibrillar proteins account for the major contribution to the HPT-induced changes. The results indicated that HPT can potentially be an effective technology to improve the digestibility of meat products. [ABSTRACT FROM AUTHOR]

The present study was performed to clarify the effects of pulsed electric field (PEF) on the physicochemical properties and conformations of myofibrillar proteins (MPs) extracted from pale, soft, exudative (PSE)-like chicken breast meat. Various PEF parameters, including the electric field intensity (0–28 kV/cm) and pulse frequency (0–1000 Hz), were varied. The results showed that as the PEF intensity increased, the solubility, surface hydrophobicity and sulfhydryl group content of the MPs were significantly improved. However, when the intensity exceeded 18 kV/cm, these properties declined, which was possibly due to protein aggregation caused by functional group interactions. Additionally, the PEF treatment altered the rheological properties of PSE-like MPs and induced the formation of low-elasticity MPs. However, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) demonstrated that the primary structure of the MPs was not altered after the PEF treatment. According to the circular dichroism (CD) spectroscopy results, the α-helix contents of the PEF-treated samples were increased but the β-turn and random coil contents were reduced. The occurrence of PSE-like chicken meat is one of the most serious quality issues worldwide and can decrease the consumer's purchasing desire and result in extensive economic losses for the poultry processing industry. MPs play a vital role in the qualitative characteristics of chicken products. As a potential novel processing technology, PEF has potential applications for improving the functionality of PSE-like chicken protein to expand its application in the food industry. • Moderate pulsed electric field (PEF) treatment significantly improved the solubility of myofibrillar proteins (MPs). • PEF processing enhanced the dynamic rheological properties of MPs. • SDS-PAGE demonstrated that protein aggregation increased with PEF treatment strength. • The surface hydrophobicity and sulfhydryl group content of MPs increased and then decreased with increasing PEF treatments. • CD spectra revealed that PEF treatment significantly changed the secondary structures of MPs. [ABSTRACT FROM AUTHOR]

In the present study, myofibrillar protein (MP) and dextran (DX) conjugates were prepared via glycation in a liquid solution. The effects of DX molecular weight on structural and emulsifying properties of conjugates compared with those of MP were investigated. The glycation was confirmed by evaluating modification degree of glycation (DG), electrophoresis and Fourier transform infrared spectroscopy. As DX molecular weight increased, the Ca2+-ATPase activity decreased markedly due to modification of MP, and the formation of MP-DX conjugates reduced surface hydrophobicity owing to the unfolding behaviour of MP and covalent attachment of DX. In addition, combined analysis of turbidity and reactive sulfhydryl contents indicated that MP may undergo a conformation unfolding and become looser and more flexible upon glycation. Glycation was able to increase the emulsifying activity and emulsion stability of MP, and MP-DX 70 showed the best emulsifying properties. A good correlation between reactive sulfhydryl contents and emulsifying properties was obtained, and the correlation coefficients were 0.930 for emulsifying activity and 0.961 for emulsion stability. Meanwhile, there was a negative correlation between surface hydrophobicity and emulsifying properties with correlation coefficients of −0.965 and −0.895, respectively. Overall, glycation could alter the structural characteristics and enhance the emulsifying properties of MP. • Myofibrillar protein (MP) was modified by glycation under aqueous conditions. • SDS-PAGE and FT-IR analysis confirmed the grafting of MP with dextran (DX). • Glycation with DX induced structural changes in MP. • The structural changes of glycated MP improved its emulsifying properties. [ABSTRACT FROM AUTHOR]