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Emulsion-type sausages were produced, at 80°C for either 0, 10, 20 or 30min, using homogeneous Taihu pork batters. Low-field nuclear magnetic resonance (LF-NMR), with or without deuterium oxide (D2O) substitution, evaluated the proton mobility states related to both water and fat molecules, or fat molecules only, respectively, in the sausage samples, during heat-induced gelation. The decreasing trend in the area proportion of main peak T21, reflected a tighter gel structure in emulsion-type sausages. Raman spectra (400-3600cm(-1)) revealed decreased α-helix, but increased β-sheet, β-turns and random coil contents, during the gelling process. Moreover, principal component analysis (PCA) showed significant correlations between secondary protein structures with distribution of water and fat in the gel matrix. Furthermore, this study established the relationship of water and fat protons mobility with changes in secondary protein structures, and described the critical time of gel formation in emulsion-type pork sausages., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

The deterioration of wooden breast myofibrillar protein (WBMP) causes a decline in its processing performance, and the protein becomes easier to oxidize. Previous studies have revealed that the use of (-)-epigallocatechin-3-gallate (EGCG) may improve the physicochemical properties and oxidative stability of proteins in aqueous solutions. The effects of varying concentrations (0.01%, 0.02%, 0.03%, and 0.04% w/v) of EGCG on the physicochemical properties of a WBMP emulsion (1.2% WBMP/10% oil) and the inhibition of lipid and protein oxidation were studied. The results revealed that a moderate dose of EGCG (0.03%) could significantly (p < 0.05) improve the emulsion activity index (4.66 ± 0.41 m2/g) and emulsion stability index (91.95 ± 4.23%), as well as reduce the particle size of the WBMP emulsion. According to the micrographs and cream index, 0.03% EGCG retarded the phase separation by stopping the aggregation of droplets and proteins, thus significantly improving the stability of WBMP emulsions. During storage at 50 °C for 96 h, 0.03% EGCG inhibited lipid oxidation (lipid hydroperoxide and 2-thiobarbituric acid-reactive substance formation) and protein oxidation (carbonyl formation and sulfhydryl loss). In contrast, lower and higher EGCG concentrations (0.01%, 0.02%, and 0.04%) demonstrated shortcomings (such as weak antioxidant capacity or protein over-aggregation) in improving the quality and oxidation stability of the emulsion. In conclusion, a moderate dose of EGCG (0.03%) can be used to improve the quality and shelf life of WBMP emulsions. [ABSTRACT FROM AUTHOR]

Summary: The effects of cellulose microfibres (CMFs, Average size: 100 ± 5 μm) and cellulose nanofibres (CNFs, Average size: 60 ± 3 nm) on the properties of myofibrillar protein (MP) gels from duck breast meat were studied. The results demonstrated that CMFs and CNFs were mostly connected to MP by non‐covalent bonds, the diffusion and cross‐linking of MP molecules was promoted, and a denser and more complete gel network was formed. With the increases of CMFs and CNFs concentration (0–10%), the hardness was increased by 13.15% and 19.78% for CMFs10% and CNFs10% gels, respectively, and the elasticity was increased by 40% and 80%, respectively. At the same concentration (0–10%), the increase in gel hardness, viscoelasticity and immobilised water content was greater in the CNFs‐MP group than in the CMFs‐MP group. The CNFs‐MP group had a tighter gel network, and CNFs had a better potential to improve the gelation performance of MP. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The effect of acidification through hydrochloric acid combined with inulin (In), and inulin/sodium alginate (In/SA) on the stability of native/thermally denatured myofibrillar proteins (MPs/TMPs) particles in an aqueous system was investigated. At the same pH, MPs-In and TMPs-In particles were smaller and had higher absolute potentials than MPs-In/SA and TMPs-In/SA particles. Additionally, the size of MPs-In particles reached 1 μm, and the solubility increased from 21.73 ± 0.57 % to 76.26 ± 1.27 % when the pH was reduced from 5.0 to 3.0. The absolute potential of TMPs 3-In particles increased from 15.77 ± 0.72 to 28.20 ± 0.30 mV, and the solubility increased from 18.65 ± 0.72 % to 74.53 ± 0.74 %. Confocal laser microscopy revealed that, compared with pH 5.0 or 4.0, MPs-In/TMPs-In particles dispersed more evenly at pH 3.0 compared with pH 5.0 or 4.0. This further confirmed that electrostatic repulsion between particles maximally contributed to particle stability. Furthermore, the α-helix content in TMPs-In particles at pH 3.0 decreased from 41.51 ± 1.09 % (TMPs control) to 16.61 ± 1.87 %. This decrement of an up to 60 % led to decreased intramolecular hydrogen bonds and improved surface hydrophobicity. Therefore, a single polysaccharide (In) combined with MPs/TMPs particles exhibited higher dispersion and stability at pH 3.0. These findings could provide new insights into chicken-derived protein beverage processing. • The solubility of MPs-In particles was 76.26 % at pH 3.0 and 8.96 % at pH 5.0. • The main particle size of MPs combined with inulin was as low as 1 μm at pH 3.0. • The hydrophobicity of MPs/TMPs particles was enhanced by adding a polysaccharide. • α-helix content of TMPs-In reduced more sharply with lowered pH than MPs-In. • The dispersion and stability of MPs-In were better than that of MPs-In/SA at pH 3.0. [ABSTRACT FROM AUTHOR]

[Display omitted] • Curcumin in the dispersed phase was detrimental to MP emulsion stability. • Appropriate dose of curcumin contributed to desirable gel formation. • Curcumin in oil phase could modulate the state of continuous phase gel network. • Curcumin in the oil phase reduced α-helix but enhanced the β-sheet of MP in gels. • Gels with denser networks favored better texture properties and retention of water. The regulation mechanism of curcumin (CUR) in the oil phase on the emulsification and gelation properties of myofibrillar protein (MP) was investigated. CUR enhanced the emulsifying activity index (EAI) of MP but decreased its turbiscan stability index (TSI) and surface hydrophobicity, which exacerbated oil droplet aggregation. Medium amounts (200 mg/L) of CUR changed the 3D network architectures of emulsion gels from lamellar to reticular, improving the gels' water-holding capacity (WHC), storage modulus, springiness, and cohesiveness. Besides, the LF-NMR revealed that CUR had limited effects on the mobility of immobilized and free water. The α-helix of MP in gels with medium amounts of CUR decreased from 51% to 45%, but the β-sheet increased from 23% to 27% compared to those without CUR. Overall, CUR has the potential to become a novel structural modifier in emulsified meat products due to its dose–response. [ABSTRACT FROM AUTHOR]

The physicochemical properties of myofibrillar proteins in their native and denatured states can be modulated to allow limited protein stabilization through rational acid treatment. Herein, the effects of varying pH values (2.5–4.5) on the stability of native and thermally induced myofibrillar proteins (MPs and TMPs, respectively) particles were studied via the addition of citric acid (CA) solutions. After heating at 80 °C, the α-helix content of the MPs particles without CA decreased from 43.40 ± 1.36 to 29.80 ± 1.15%. At identical environmental pH, the TMPs particles formed by heating had difficulty forming aggregates, and their size of without CA (10 μm) was smaller than that of the MPs particles (1 mm). Optical microscopy results revealed that the dispersion of the TMPs particles was improved upon CA addition, unlike that of the MP particles. However, the carbonyl content of MPs particles is lower than that of TMPs particles, and the total sulfhydryl content is higher than that of TMPs particles. In addition, as the pH of TMPs particles is adjusted to 2.5, protein content increased from 9.28 ± 1.05 to 82.37 ± 1.37 mg/mL, and optical microscopy images showed that the TMPs particles at pH 2.5 were more dispersed than those at other pH values tested herein. Therefore, the TMPs particles at pH 2.5 exhibited high stability in aqueous phase. [Display omitted] • The dominating particle size of TMPs at pH 2.5 is visibly higher than that of MPs. • The maintenance of solubility and dispersion of TMPs at a lower pH is superior to MPs. • TMPs particles have better stability than MPs at pH 2.5–4.5 during 5 d storage. • The oxidation stability of TMPs is weaker than that of MPs at pH 2.5–4.5. • The hydrophobicity of MPs/TMPs particles is enhancive by adjusting pH to 2.5–4.5. [ABSTRACT FROM AUTHOR]

• The physicocization and microstructure of MP at different temperatures were studied. • The properties of glucose and cellulose nanofibers modified MP were investigated. • Glc and CNFs influenced MP by hydrogen bonds and molecular steric hindrance. • Glc and CNFs improved the thermal stability of MP at 80 °C and 100 °C. • The interaction mechanism of Glc and CNFs on MP was preliminarily illustrated. The effects of unheated, 80 °C, 100 °C, and 121 °C on the physicochemical and microstructural properties of myofibrillary protein (MP) supplemented with glucose (Glc) and cellulose nanofibers (CNFs) were studied. The results showed that Glc and CNFs cross-linked with MP through non-covalent bonds when unheated compared with the unheated MP group, which increased the particle size and surface hydrophobicity of MP, and changed the secondary structure. At 80 °C and 100 °C, the particle size and hydrophobicity of MP significantly increased. At 121 °C, the contents of leucine and lysine in MP decreased by 16.2% and 19.9%, respectively, however, both Glc and CNFs could prevent this decrease. Meanwhile, microscopic images showed that the dispersion of Glc-MP and CNFs-MP were more uniform than the MP groups. Compared with Glc-MP, CNFs-MP had more uniform particle size distribution and better thermal stability at high temperatures (121 °C). [ABSTRACT FROM AUTHOR]

• Glycation to improve wooden breast myofibrillar protein (WBMP) physicochemical properties. • Molecular structure changes at conformation and microstructure levels of sugar-WBMP. • Physicochemical and molecular changes on the solubility of conjugates. • Reaction mechanism of sugars to improve the physicochemical properties of WBMP. The effect of diverse glycation strategies on the physicochemical and structural properties of wooden breast myofibrillar protein (WBMP) were studied. The WBMP was mixed with D-ribose (RI), sodium alginate (SA), and glucosamine (GH) respectively in a weight ratio of 1:2 (w/w) at 70 °C, and was heated for 6 h. Atomic force microscopy and particle size results showed that the glycation reaction in the presence of RI made WBMP to be more evenly dispersed in the solution and had a significantly smaller particle size (78–955 nm, average 361.06 nm) (P < 0.05). There was an increase in WBMP-RI solubility (76.23 ± 0.56%) and α-helix content (51.23 ± 1.1%) than other groups. Compared with WBMP-RI, WBMP-SA and WBMP-GH have poor performance in particle distribution, solubility and emulsification. This study clarified the aldehyde group in aldose was more suitable for the glycation modification of WBMP than the ketone group in ketose. [ABSTRACT FROM AUTHOR]

The development of myofibrillar proteins drinks (MPDs) can provide meat protein nutrition to specific groups of people. However, one major challenge is that myofibrillar proteins (MPs) are insoluble in solutions with a low ionic strength. Another functional constraint is the susceptibility of MPs to heat-induced aggregation. Currently, the primary approach used to improve the water solubility of MPs is to inhibit the assembly of myofilaments. Increasing the thermostability of MPs primarily inhibits the aggregation of myosin or oxidizes myosin to soluble substances. This review focuses on the description of several chemical and physical strategies, with an emphasis on the advantages, disadvantages, and recent progress. Under the myosin filament assembly process and the cross-linking aggregation mechanism, this summary helps improve our understanding of the solution and thermostability of MPs in low-ionic-strength solutions, thus providing new ideas to the development of MPDs. [ABSTRACT FROM AUTHOR]

• Salt soluble proteins from Rhodotorula glutinis (RGP) were extracted by sonication. • The RGP and transglutaminase (TG) were added into myofibrillar proteins (MP) • WHC, hardness, springiness, and immobilized water were enhanced for MP-RGP-TG gel. • Increases in ' gauche-gauche-trans ' S S bonds and β-fold of MP-RGP-TG gel were found. • Thermostability of myosins and actins from MP was reduced by TG and/or RGP. Some microbial single-cell proteins are capable of producing synergistic crosslinking interactions with edible proteins by rational regulation. Herein, we reported that salt soluble proteins (RGP) extracted from Rhodotorula glutinis in an alkaline and saline system may combine with myofibrillar proteins (MP) by transglutaminase (TG) polymerization to form improvable irreversible thermal co-gels. The combination of MP, RGP, and TG, namely restructured MP gels, led to significantly enhanced water holding capacity (WHC), up to 90.76 ± 1.88% (% of retained water) and textural properties (hardness, springiness, and adhesiveness) as well as decreases of ' gauche-gauche-gauche' S S bonds and α-helix conformations and increases of ' gauche-gauche-trans' S S bonds and β-fold conformations, compared to MP and MP-RGP groups. Differential scanning calorimetry analysis validated that thermostability of myosins and actins from MP was reduced after using RGP, TG, and their combination, and unfolding and denaturation of myosin occurred easily during thermal co-gelation by TG and/or RGP. [ABSTRACT FROM AUTHOR]