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The influences of ultrasound thawing (UT) at different power (0, 100, 300, and 500 W) on the oxidation, aggregation, and gel properties of common carp (Cyprinus carpio) myofibrillar protein were evaluated in the present study. The free amino content, carbonyl content, dityrosine content, and TBARS value of UT-300 were significantly lower than those of other thawing groups (P < 0.05), suggesting that appropriate ultrasound power (300 W) thawing inhibited the oxidation of myofibrillar protein and fat. However, excessive power (500 W) UT enhanced the oxidation of fish protein. UT-300 had the smallest surface hydrophobicity, particle size, and turbidity values, indicating that UT-300 reduced protein aggregation caused by thawing. At the same time, UT-300 protein gel had a higher gel strength and water-holding capacity than other thawing treatments, which were characterized by fine and uniform gel networks. Water distribution analysis also proved that UT-300 inhibited the loss of bound water, free water, and immobilized water, as well as the increase in fluidity caused by thawing. In conclusion, proper power (300 W) UT was beneficial in inhibiting the degradation of gel properties caused by protein oxidation and aggregation during thawing. • Ultrasound thawing at 300 W (UT-300) inhibited protein oxidation caused by thawing. • UT-300 inhibited the protein aggregation caused by thawing. • UT-300 had the highest gel strength/water holding capacity among all thawing methods. • Proper power UT was beneficial for maintaining the gel properties during thawing. [ABSTRACT FROM AUTHOR]

In this study, Scomberomorus niphonius surimi was used as the food-ink for 3D printing and microbial transglutaminase (MTGase) as additive, aiming to investigate the effects of MTGase on the forming ability, physical properties and structural qualities of surimi and its 3D printed products. As per the rheological and printing results, the apparent viscosity of surimi containing 0.2% and 0.3% (w/w) MTGase facilitated the extrusion of surimi from the nozzle in time. In addition, the high storage modulus obtained with the two concentrations of enzyme was conductive to the maintenance of shape and appearance after printing of the 3D printed gels. The gel strength reached the maximum value of 2517.89 g mm at 0.3% MTGase concentration, and as the MTGase content increased from 0 to 0.4%, there was a gradual increase in hardness, cohesiveness and resilience of the printed gels. The gel structure changed from irregular distribution to a tight and uniform network that enhanced the ability to restrain residual water, as observed with Nuclear Magnetic Resonance (NMR). On the contrary, cooking loss increased from 4.16% to 13.49%. The results suggest that the use of MTGase can effectively improve the 3D printability, viscoelastic properties, mechanical properties and microstructure of surimi gels. • 3D printing technology capable of creating a surimi food. • Microbial transglutaminase improves the extrudability of surimi. • Incorporating microbial transglutaminase impacts surimi 3D printability. [ABSTRACT FROM AUTHOR]

In this study, high internal phase emulsions (HIPEs) using casein as stabilizer and soybean oil and Litsea cubeba oil (LCO) as internal phase were prepared and added into silver carp surimi. The effects of LCO-HIPEs on the gel and flavor properties of surimi product were studied. After chopping, heating and storing, LCO-HIPEs showed emulsion droplets with particle size of 11 μm and remained solid structure. Compared with Oil-added surimi gels, HIPEs-added groups exhibited higher gel strength, water holding capacity and whiteness. Low-field NMR analysis revealed that HIPEs-added gels had higher proportion of bound water and immobilized water. Microstructure observation showed that LCO-HIPEs emulsion droplets in gel were smaller and evenly distributed. Moreover, SDS-PAGE showed that myosin heavy chain band in HIPEs-added gel were more attenuated than that of their Oil-added counterparts after 40 °C or 90 °C heating. HIPEs-added groups also showed higher amount of volatile compounds but lower thiobarbituric acid reaction substances value than Oil-added ones. Thus, LCO-HIPEs could be applied in surimi products to fortify flavor feature and provide fairly good gel properties and lipid oxidation stability. • LCO-HIPEs stabilized by casein had good gel-like properties and stability. • HIPEs-gels had higher gel strength and water holding capacity than Oil-gels. • More myosin were involved in gelation period in HIPEs-gels than in Oil-gels. • HIPEs-gels had lower thiobarbituric acid reaction substances value than Oil-gels. • HIPEs-gels had more enriched flavor compounds than Oil-gels. [ABSTRACT FROM AUTHOR]

Ultraviolet light-emitting diodes (UV-LEDs) have become widespread for decontaminating the surfaces of food products and their packaging as a safer alternative to traditional mercury-vapor based UV lamps. This study aimed to investigate the effect of UVC- LEDs (275 nm) on the inactivation of foodborne pathogens and quality attributes of raw tuna fillets. Raw tuna fillets inoculated with cocktails of Salmonella Typhimurium, Listeria monocytogenes , and Escherichia coli O157:H7 were exposed to UVC-LEDs at 500-4000 mJ/cm2. UVC-LED treatments of single-layer tuna fillets at a dose of 4000 mJ/cm2 resulted in 1.31-, 1.86-, and 1.77- log reduction of S. Typhimurium, L. monocytogenes , and E. coli O157:H7, respectively. The pH value, water-holding capacity, metmyoglobin, texture, and color characteristics of tuna fillets were not significantly (p > 0.05) changed following the UVC-LED treatment at radiation doses up to 4000 mJ/cm2. Nonetheless, the UVC-LED irradiation led to increased levels of lipid oxidation in tuna fillets. Overall, the present study demonstrates that UVC-LEDs are a promising technology to reduce microbial flora and maintain the physicochemical properties of fish products. • UVC-LEDs decreased foodborne pathogens incubated on raw tuna fillets. • UVC-LEDs showed higher germicidal efficiency for TSA plates than raw tuna fillets. • Quality attributes of raw tuna fillets were maintained after UVC-LEDs treatment. • UVC-LEDs irradiation led to increasing levels of lipid oxidation in tuna fillets. [ABSTRACT FROM AUTHOR]

Fucoxanthin (FX), a non-provitamin A carotenoid pigment, is a well-known natural antioxidant contained in brown algae. The present study deals with an ultrasonic-assisted FX extraction process from Undaria pinnatifida with rapeseed oil as the solvent. Then, high internal phase emulsions (HIPEs) with the FX-rich rapeseed oil as the oil phase was constructed using a simple one-step method for food 3D printing. The FX-loaded HIPEs were stabilized by the gelatin (GE)-based microgel, which were prepared by GE complex coacervation with sodium alginate and transglutaminase cross-linking, for the improved delivery and stability of FX. FX-loaded HIPEs stabilized by 2 wt (wt)% GE-based microgel showed a small and uniform particle size and a stable microstructure. The HIPEs stabilized by 2 wt% GE-based microgel had the best FX stability (residual FX 84.81 ± 0.82%) and bioaccessibility (38.26 ± 1.21%). The excellent viscoelasticity, recovery rate and thixotropy of the HIPEs stabilized by 2 wt% GE-based microgel further confirmed the best 3D printing performance. Therefore, rapeseed oil as the extraction solvent motivates FX-loaded HIPEs preparation, and GE-based microgel concentration is crucial for 3D printing. [Display omitted] • Extracted fucoxanthin with rapeseed oil can be directly used as emulsion oil phase. • Colloidal stability was improved by complex coacervation of 8:1 gelatin-alginate. • Microgel particles improved the stability of high internal phase emulsions. • The bioaccessibility of fucoxanthin was improved by high internal phase emulsions. • Such a rheologically stable emulsion has a potential application in 3D printing. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effects of four different flavour-masking soak treatments on Spanish mackerel (Scomberomorus niphonius) using sensory evaluation and instrument based analyses. The four treatments included rosemary extract (1700 mg/L), a commercial deodorizing solution named Wenda (0.758 mg/L), black tea powder (15000 mg/L), and perilla extract (217 mg/L). The study utilised e-nose, water content, water holding capacity, 2D-LF-NMR, and Texture Profile Analysis (TPA) to assess the effects of these treatments. Preference mapping and PLSR analysis were used to investigate relationships between different indicators. All four treatments significantly reduced the fishiness of fish, and cooked fish hardness and firmness both correlated positively with overall preference. The PLSR results revealed that cooked fish firmness and hardness correlated strongly with its water holding capacity and water signal to centre-mass ratio, respectively. This study provides valuable insights to guide development of flavour-masking treatments for Spanish mackerel and other fish products. • T 1 -T 2 relaxation profiles of different samples were conducted for water-texture correlation. • Preference mapping was conducted in mackerel evaluation. • The relationship between sensory and instrumental analysis was explored by PLSR analysis. [Display omitted] [ABSTRACT FROM AUTHOR]

The microbial community of spontaneously fermented fish plays an important role in product sensory quality. Recently, microbiota research has seen a shift in perspective from taxonomy to function. The investigation of the microbial community metaproteome will reveal information on strains as well as the expressed proteins to better understand the roles of the microbiota in fermented fish. In this study, shotgun metaproteomic methods were used to identify and annotate 2175 proteins from the traditional Chinese fermented fish Siniperca chuatsi . These proteins belonged to 553 bacterial strains of 19 phyla, including 10 strains of lactic acid bacteria. Based on the KEGG annotation system, 1217 proteins were found to be involved in metabolic pathways, among which 352 proteins were related to amino acid metabolism. Specifically, 63 amino acid degradation-related proteins were identified in Streptococcus sp., Bacillus sp., Escherichia sp., and Pseudoalteromonas sp., which indicated that these strains were potential candidates for generating aroma compounds and thus contributors to the special flavour of the fermented fish. This information on metaproteomes in fermented S. chuatsi increases the understanding of microbial metabolic modes and leads to knowledge-based improvements of the stability and palatability of fermented fish. [ABSTRACT FROM AUTHOR]

This study was aimed to explore the mechanism of peptides antioxidant activity improvement treated by pulsed electric field (PEF). The pine nut ( Pinus koraiensis Sieb. et Zucc) peptides were used as the experimental materials. DPPH radical inhibition and cellular antioxidant activity (CAA) were applied to evaluate the peptides antioxidant activity. Structures of PEF-treated peptides were analyzed by mid-infrared (MIR) and circular dichroism (CD) spectroscopy. Peptides were indentified including Gln-Cys-His-Lys-Pro, Gln-Cys-His-Gln-Pro, Lys-Cys-His-Gln-Pro(KCHQP), and Lys-Cys-His-Lys-Pro. KCHQP was with the strongest DPPH radical scavenging of 89.10% ± 0.20%, and CAA units of 78.40 ± 1.71. Moreover, the DPPH radical scavenging of KCHQP was significantly increased from 89.10% ± 0.20% to 93.22% ± 0.09% under the PEF treatment conditions (pulse frequency 1800 Hz, and electric field intensity 15 kV/cm). The MIR and CD spectroscopy indicated that the structure of KCHQP was not changed by PEF. However, the zeta potential was reduced from 11.6 ± 0.28 mV to 0.4 ± 0.06 mV. This study enriched the resource of antioxidant peptides with indentified amino acid sequence. It provided a way to investigate mechanism of peptides antioxidant activity improvement treated by PEF. [ABSTRACT FROM AUTHOR]

Although pork fat provides a good flavor to food, it is associated with the development of cardiovascular diseases and obesity. In our study, cod protein-stabilized and casein-stabilized high internal phase emulsions (HIPEs) were applied as substitutes for pork fat to create healthy surimi products. The effect of replacement amount (10%, 30%, 50%, and 70% of pork fat) on the rheology and differential scanning calorimetry of fish cake paste, as well as the texture quality, moisture distribution, and microstructure of fish cakes (FCs), were studied. The addition of HIPEs significantly improved the tenderness and whiteness of FCs. Gel strength was balanced after adding appropriating HIPEs, which was revealed by storage modulus and loss modulus values of fish cake pastes. The addition of HIPEs improved the distribution of water and oil in FCs and increased the binding ability of protein and water to ensure that the gel network structure can better "capture" water and oil, resulting in similar gel strength with a tender and healthier FCs. Under the same replacement amounts, there were some differences in the texture quality of FCs with different HIPEs, which might be caused by differences in the water content and texture of the two kinds of HIPEs. • High internal phase emulsions (HIPEs) could replace pork fat to prepare fish cakes. • Gel network of fish cake with HIPEs could better "capture" water and oil. • Fish cakes with casein and cod protein HIPEs showed a bit of textural difference. [ABSTRACT FROM AUTHOR]

There is a growing consumption on puffer fish-based food since this species contains high nutritional properties in terms of high protein and low fat values. However, this is hampered by the tough texture of puffer muscle. In this study, a simple but robust strategy to improve the tenderness of puffer muscle by papain treatment of different concentration (60, 80, 100, 120 and 140 U/mL) was developed. Results showed that the shear force and the hardness of fish muscle decreased significantly with increasing papain concentration, indicating improved tenderness of fish muscle. Protein patterns from SDS-PAGE confirmed that the papain-treated muslces had increasing degrees of degradation with faded myosin heavy chain (MHC) band and actin band as well as an increasing amount of low molecular weight pepeptides around 25–35 kDa. This may associated with the loss of one major protein denaturation peak as revealed by differential scanning calorimetry (DSC). Conformational characterization showed that the relative content of α -helix decreased, while irregular coil structure increased with increasing papain concentration. These results suggested puffer myofibril proteins, mainly myosin and actin were hydrolyzed into low molecular peptides with more disorder structures, which might be responsible for the improved tenderness. • Papain treatment resulted in improved tenderness of puffer fish muscle. • Degradation of myosin heavy chain and actin was observed after treatment. • Papain treatment led to increase in irregular coil structure but increase in α-helix. • The relation between tenderization and myofibril protein changes was confirmed. [ABSTRACT FROM AUTHOR]

the present study aimed to examine the effects of cooking temperatures on meat quality, protein carbonylation and protein cross-linking of fresh beef with different packaging methods. Steaks from beef tenderloins were packed in vacuum or high oxygen modified atmosphere (MAP), and stored for 10 days at 4 °C. After storage, steaks were cooked to different internal temperatures (52, 62, 72 °C). In general, when cooked to higher temperature, MAP packed beef had higher cooking loss, larger values of shear force and smaller values of redness than vacuum packed beef. Meanwhile, increasing cooking temperature generally caused more formation of protein carbonyls - α-aminoadipic semialdehyde (AAS) and protein cross-links - lysinonorleucine (LNL), and high oxygen MAP was found to intensify their formations. Increased protein carbonylation via AAS formation and protein cross-linking via the LNL formation seemed to play an important role in quality deterioration of high oxygen MAP packed beef. • Higher cooking temperature led to quality deterioration in beef packed in high oxygen. • Increased amounts of α-aminoadipic semialdehyde were generated in MAP packed beef. • MAP packaging promoted the formation of non-disulfide protein cross-links by lysinonorleucine. [ABSTRACT FROM AUTHOR]

In this study, κ-carrageenan was used as an additive to improve the quality of Hypophthalmichthys molitrix -sea cucumbers (HM-SC) compound surimi gel. The effects of κ-carrageenan on rheological properties, gel strength, textural and moisture characteristics, as well as microstructure of the HM-SC surimi gel were investigated, alongside with Fourier transform infrared (FT-IR) spectroscopic characterization and SDS-PAGE analyses of the compound materials. Rheological tests showed that addition of κ-carrageenan increased the storage modulus of the HM-SC compound materials in a dosage-dependent way, which led to superior shape-forming and shape-keeping abilities in 3D printed products. The best gel strength of 1236.04 g mm was obtained in samples with κ-carrageenan addition at 1.5% (w/w). The microstructure of the HM-SC compound surimi gel became more compact and denser, with improved connectivity. These samples also had reduced cooking loss and improved water holding capacity, confirmed by changes in water mobility characterized through Low-field nuclear magnetic resonance (LF-NMR). Moreover, κ-carrageenan addition did not change protein configuration much, neither was it contributed to the aggregation and degradation of proteins. These results showed that the quality of the HM-SC compound material could be improved with the κ-carrageenan addition, which could make it suitable for 3D printing based novel product development. • 3D printing technology for making HM-SC compound surimi product. • κ-Carrageenan improves the quality of HM-SC compound surimi gel. • κ-Carrageenan improves printability of HM-SC compound material. [ABSTRACT FROM AUTHOR]

Cod cut offs, as a by-product of cod processing, is often discarded and wasted. A cod protein gel (CP-gel) was produced from homogenized steamed cod cut offs to turn the otherwise "waste" into treasure. The effects of homogenizing conditions on the physicochemical properties of the CP-gel were investigated by assessing the gel strength, water holding capacity (WHC), rheological properties and microstructure, combined with the visual appearance. After homogenization at 80 MPa with 15 passes, the particle size was reduced to 4 μm and resulted in a gel strength of 0.63 N. The WHC of cod protein gel increased by 41% as compared to the un-homogenized sample. The secondary structures of the microfibrillar proteins changed as evidenced by the increased α-helix content by 3% via homogenization. The reduced particle size allowed particle-particle interactions and promoted protein cross-linking via both hydrophobic interaction and hydrogen bond formation. A relatively smooth and honeycombed network structure was formed with improved gel quality and physical properties. CP-gel provides a potential to utilize cod cut offs to produce value-added products. • Homogenizing the steamed cod cut offs resulted in cod protein gel. • The particle size and gel strength were affected by the homogenization conditions. • Reduced particle size provided more chance to cross-link and network formation. [ABSTRACT FROM AUTHOR]

In this study, the effects of different extraction temperatures (45, 60 and 75 °C) and pH (3 and 5) on the physical and functional properties of tilapia skin gelatin (TSG) were investigated. The extraction yield of TSG is from 11.67 to 41.91% (based on dry weight), and the highest was obtained at 75 °C/pH 3. The TSG extracted at 45 °C showed strong band intensity of α-chains and cross-linked components with higher molecular weight (MW) > 120 kDa, while other TSG samples resulted in faded bands with the presence of fragments (<85 kDa). Higher contents of imino were detected in TSG with higher MW. Gel strength, apparent viscosity, and gelling temperature varied with different extraction temperatures and pHs, where higher values were observed in TSG with higher MW. These results are supported by circular dichroism analysis, in which more triple helix structures were found in TSG with higher MW. All TSG solutions can form gels at 4 °C, while at room temperature, only TSG obtained at 45 °C can set. These results highlight the significance of extraction conditions which may be used to tailor the physical and functional properties of TSG. • Physicochemical properties of TSG were investigated. • The molecular distribution and triple helix content of TSG deepens on extraction conditions. • The effect of pH on the properties of TSG requires a high temperature synergy. • Different extraction conditions allowed TSG with tailored functional properties. [ABSTRACT FROM AUTHOR]

The effects of addition of microbial transglutaminase (MTGase) on gel forming properties of frozen stored longtail southern cod mince (LSCM) were investigated at different incubation temperatures (35 °C, 40 °C, 45 °C, 50 °C). The results showed that frozen stored LSCM had poor gel-forming ability. With MTGase addition, the gel-forming ability of the LSCM was significantly improved, with the best performance obtained at 35 °C heating for 2 h. MTGase promoted myosin cross-linking, which led to an increase in gel strength. Circular dichroism analysis revealed that the myosin rod went through unfolding in two phases, at 30 °C and 38.5 °C, respectively. At 35 °C, myosin rod was only partially unfolded, with 40% helical structures remained which appeared to play critical roles in promoting intermolecular cross-linking. According to the scanning electron micrographs, the higher connectivity and lower porosity was correlated to the higher gel strength. This study showed that the effect of MTGase could be synergistically combined with proper selection of incubation temperature and time to improve gelation properties of fish mince products. • Microbial transglutaminase improves the gel properties of the frozen fish mince. • The partial unfolding of myosin rod play an important role in gel formation. • Myosin rod structure on the transglutaminase-induced gelation to improve the process. [ABSTRACT FROM AUTHOR]

The study investigated effects of gallic acid (GA, 0, 1, 5, 25 and 125 μmol/g) on properties of oxidatively stressed Japanese seerfish myofibrillar protein (MFP). Results showed that GA alleviated carbonyls formation and protected free amine. 5 μmol/g GA stabilized sulphydryls and secondary structure while 125 μmol/g GA enabled great loss of sulphydryls and reduced α-helix structure. Analysis of tryptophan fluorescence and surface hydrophobicity indicated that GA induced the unfolding of MFP structure but not in a dose-response fashion. Polymers were formed along with marked attenuation of myosin heavy chain in MFP with 125 μmol/g GA, and its particle size was the largest. Compared with purely oxidized MFP, MFP with 125 μmol/g GA showed a radical peak with narrower peak width but higher intensity. Results imply that high dose GA formed thiol-quinone adducts, enhancing polymerization. It also formed stable protein-bound phenoxyl radicals, inhibiting protein oxidation. Compared with non-oxidized group, storage modulus of MFP with 5 μmol/g GA increased sharply but that of MFP with 125 μmol/g GA decreased distinctly. The study suggests the role of GA on MFP depends much on its dose. Low dose GA could be used for improving fish MFP gelling property. • GA alleviated carbonyls formation, protected free amine, induced structure unfolding. • Sulphydryl and α-helix structure content was stable in OX+5 but declined in OX+125. • New polymers formed along with attenuation of MHC band in OX+125. • G′ of OX+5 increased while G′ of OX+125 decreased compared with it of NOX. • OX+125 radical peak showed narrower width, higher intensity than OX+0 radical peak. [ABSTRACT FROM AUTHOR]