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The iTRAQ-based quantitative proteomic strategy was used to reveal the effects of magnetic nanoparticles plus microwave thawing (MNPMT) on the largemouth bass fillets quality. A total number of 47 proteins were identified as differentially abundant proteins (DAPs) in fillets treated by microwave thawing (MT), while 13 DAPs were in MNPMT. Bioinformatics analysis of Gene ontology (GO) enrichment, Kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment, Protein-protein interaction (PPI) and subcellular localization prediction of DAPs showed that many DAPs were involved in protein structure, metabolic enzymes, protein turnover and so on. The correlation analyses indicated that 14 DAPs were significantly related with the fillet quality traits. Besides, several discovered proteins might be potential protein markers for pH, color, cooking loss and centrifuge loss of thawed largemouth bass fillet quality. These results provided a further understanding of quality stability of largemouth bass fillet treated by MNPMT from the perspective of proteomics., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The influence of ultrasonics combined with microwave thawing (UMT) and ultrasonics combined with far-infrared thawing (UIT) on the water migration and protein denaturation of red drum were studied. Five treatments were used: ultrasonics thawing (UT), microwave thawing (MT), far-infrared thawing (IT), UIT and UMT were used for thawing red drum filets. Moisture migration and protein aggregation were studied using nuclear magnetic resonance (NMR) and particle size, respectively. Raman spectra and fluorescence spectra were used to study the secondary and tertiary structure of protein. SEM was done to observe the fiber microstructure. The results showed that UMT and UIT can maintained protein stability more than other thawing methods and retained the fiber structure of the muscle. Besides, immobilized water in fiber bundles network also had no significant changes compared with fresh samples. Thus, ultrasonics combined with far infrared or microwave thawing were used to decrease protein denaturation and water migration during the thawing of Red drum fillets., (Copyright © 2019 Elsevier B.V. All rights reserved.)

In order to evaluate the effects of magnetic nanoparticles plus microwave (MNPMT) or far-infrared (MNPFT) thawing on protein conformation changes and moisture migration of red seabream (Pagrus major) fillets, cold storage thawing, microwave thawing, MNPMT, far-infrared thawing and MNPFT were subjected to red seabream fillets. DSC and dynamic rheology were conducted to analyze physicochemical changes. Raman spectra before and after isotope H/D exchange, intrinsic fluorescence and UV second derivative spectra were carried out to explore myofibrillar protein structural changes. Low-field NMR was used to test water migration. SEM was performed to observe fiber microstructure. Results indicated that MNPMT and MNPFT both had a desirable thermal stability and gelation property. Besides, both showed stable protein secondary and tertiary structure. Immobilized water in them also had no significant changes compared with fresh sample. This research provided some novel thawing technologies for application in food industry., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Ultrasound assisted vacuum thawing (UVT) or microwave vacuum thawing (MVT) with red seabream fillets were compared to fresh, chill storage thawing, vacuum thawing, microwave thawing and ultrasound thawing. The thermal stability and gelation properties were studied with DSC and dynamic rheology, respectively. Raman spectra before and after H/D isotope exchange and intrinsic fluorescence were used to measure protein secondary and tertiary structure. Low-field NMR was done to measure water migration. The two thawing techniques both retained actin thermal stability and generally retained more stable tertiary structures than the other thawing methods. MVT showed a desirable viscoelasticity of muscle proteins and UVT had a relatively stable secondary structure. There were no significant changes in free water. Thus, UVT and MVT could be used to improve the physicochemical properties of proteins during thawing of fillets., (Copyright © 2018 Elsevier B.V. All rights reserved.)

BACKGROUND: The consumption of frozen foods inevitably involves a thawing process. Protein conformation changes during a short thawing process and the quantification of their effects remains challenging. Molecular dynamics simulations can be used to evaluate the conformational changes of protein occurring in food processing. RESULTS: In the present study, four different thawing methods were used [i.e. magnetic nanometer combined with microwave thawing (MT‐Mag), magnetic nanometer combined with radio frequency thawing (RT‐Mag), radio frequency thawing (RT) and microwave thawing (MT)] to change the conformation of myosin heavy chain (MHC). The results obtained showed that, compared with the fresh sample, the hydrogen bond number and radius of gyration of the RT‐Mag and RT groups were less decreased. Visual molecular dynamics STRIDE analysis showed that the content of the α helix was relatively high in the RT‐Mag and MT‐Mag groups. CONCLUSION: These simulation results indicate that RT‐Mag can be used as an effective method for promoting the thawing process of fish and better stabilizing the protein structure. These conclusions provide a theoretical realization for understanding the protein conformational transition during the thawing process and the realization of quantification and also provide guidance for choosing better thawing conditions without loss of nutritional properties. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

This study examined the effects on conformation and oxidation of myofibrillar protein in largemouth bass by different thawing methods. The conventional thawing, microwave thawing, microwave (MVT) or ultrasound combined with vacuum thawing, microwave or far‐infrared thawing (FMT) combined with magnetic nanoparticles were used in this experiment. The physicochemical changes were analyzed by differential scanning calorimetry and dynamic rheology. The protein structure changes were measured by Raman, intrinsic fluorescence, and second‐derivative ultraviolet spectrometry. The degree of protein aggregation was evaluated by surface hydrophobicity, particle size, and zeta‐potential measurements. Total sulfhydryl content, protein carbonyl content, Ca2+‐ATPase activity, and SDS‐PAGE were used to analyze the degree of protein oxidation. Results showed that MVT and FMT samples had better thermal stability, more stable protein conformation, and a lower degree of protein oxidation. Thus, these two methods would be beneficial to sustain the quality of thawed fillets. Practical Applications: In the market circulation, largemouth bass (Micropterus salmoides) need to be frozen. The thawing methods can directly affect the quality of frozen fish, thus causing the changes in the conformation of the myofibrillar protein in fish, and also affecting the degree of protein oxidation. The results showed that the microwave combined with vacuum and the magnetic nanoparticles combined with far‐infrared thawing had less effect on myofibrillar protein of fish and were a better thawing method. [ABSTRACT FROM AUTHOR]

The volatile flavor characteristics of largemouth bass (Micropterus salmoides) fillets thawed by magnetic nanoparticles plus microwave thawing (MNPMT) were compared with those of fresh samples thawed by chill storage thawing (CST) and microwave thawing (MT). The strategies of headspace solid-phase microextraction (HS-SPME), gas chromatography mass spectrometry (GC-MS), gas chromatography-olfactometry (GC-O), aroma extract dilution analysis (AEDA), and sensory evaluation were applied to analyze the aroma-active compounds. The results of GC-MS showed that 24 kinds of volatile compounds existed in largemouth bass fillets. Orthogonal partial least squares discriminate analysis (OPLS-DA) (R2Y = 0.979, R2Y = 0.98, Q2 = 0.695) showed ethanol, hexanal, 2,6,10,14-tetramethyl-pentadecane, and (E)-9-octadecenoic acid were responsible for the flavor differences in MNPMT, MT, and CST. In GC-O measurement, 14 kinds of volatile compounds were detected, and MNPMT had similar aroma-active compounds with the fresh sample. The grassy (score = 1.58) and leafy (score = 0.75) odors were weak in MT, but the fishy odors (score = 1.5) were strong. All results showed the MNPMT samples had less changes in aroma composition compared with the fresh sample. [ABSTRACT FROM AUTHOR]

The present study investigated the effects of CS@Fe 3 O 4 nanoparticles combined with microwave or far infrared thawing on microbial diversity of red seabream (Pagrus major) fillets in terms of thawing loss, pH, TVB-N, classical microbiological enumeration and high-throughput sequencing, and the same parameters were also studied for 24 h after thawing. Four thawing methods were used: microwave thawing (MT), far-infrared thawing (FT), CS@Fe 3 O 4 nanoparticles combined with microwave thawing (CMT) and CS@Fe 3 O 4 nanoparticles combined with far-infrared thawing (CFT). The results showed that CFT and CMT had lower values of pH and TVB-N compared to the FT and MT. Based on conventional microbial count analysis, CFT and CMT samples also maintained lower TVC, pseudomonas and LAB counts. Using high-throughput sequencing analysis, Compared with FT and MT, CFT and CMT samples showed a significant decrease in the proportion of the Pseudomonadaceae flora. However, the proportion of Pseudomonas, Bacillaceae and Thermaceae also increased significantly after 24 h of storage, which indicated that become the predominant microbiota in red seabream (Pagrus major) fillets. • Four thawing methods were studied in red seabream by high-throughput sequencing. • The thawing method of CS@Fe 3 O 4 nanoparticles plus microwave or far infrared was used. • CFT and CMT decreased the community richness and microbial communities bacterial diversity. [ABSTRACT FROM AUTHOR]

The effects of magnetic nanoparticles combined with microwave thawing (MNPMT) and magnetic nanoparticles combined with far-infrared thawing (MNPFT) on the freshness and amines content of red seabream fillets were investigated. Four thawing methods were used: microwave thawing (MT), far-infrared thawing (FIRT), magnetic nanoparticles combined with microwave thawing (MNPMT) and magnetic nanoparticles combined with far-infrared thawing (MNPFT). The quality of the fresh sample, the sample after thawing and thawed sample after being stored for 6 h were compared by measuring the freshness indexes such as the volatile amino nitrogen content, thiobarbituric acid content, pH value, total number of viable colonies, and the food safety evaluation indexes such as the formaldehyde, dimethylamine, trimethylamine and putrescine contents. The results showed that MNPFT and MNPMT can maintain better freshness than microwave and far-infrared thawing, and the increase in amines content was significantly inhibited. • Two methods of combined thawing have been proposed. • Effect of four thawing methods on the freshness and safety was analyzed. • Magnetic nanoparticles plus microwave or far infrared thawing works better. [ABSTRACT FROM AUTHOR]

This work was aimed to explore the effects of different thawing strategies on the properties of sea bass myofibrillar protein (MP) and organization structure. Results revealed that magnetic nanometer combined with radio frequency thawing (RT-Mag) and magnetic nanometer combined with microwave thawing (MT-Mag) increased the α-helical content and decreased β-sheet content, while RT-Mag had minimal effect on the secondary protein structure. Low-field nuclear magnetic resonance and SEM analysis revealed that RT-Mag and radio frequency thawing (RT) reduced the mobility and loss of immobilized and non-mobile water, had the most compact and ordered network structure. Decreases in the T max and enthalpies were observed in the thawing treatments expect for RT-Mag during the thawing process. The appearance of polymerized protein band of SDS-PAGE indicated that RT-Mag and MT-Mag occurred a mild oxidation. In addition, the changes of particle size indicated that MP pretreated by RT-Mag and MT-Mag had less aggregation and degradation. The UV second derivative showed that the effect of RT-Mag treatment was closer to that of FS, and the improvement effect of protein aggregation and oxidation was better. Therefore, RT-Mag of New thawing method can be used as an alternative method to improve MP performance and meat quality. ● The two new thawing method of RT-Mag and MT-Mag were adopted. ● Protein structure and thermal stability of sea bass thawed by different methods were studied. ● RT-Mag and MT-Mag could improve MP performance and meat quality. [ABSTRACT FROM AUTHOR]