Effect of heat treatment duration on the interaction between fish myosin and selected flavor compounds

Elucidation of key fatty aroma compound contributing to the hepatopancreas of Eriocheir sinensis using sensomics approach by GC-IMS and GC-MS-O

Aroma is one of the most noticeable characteristics when consuming Chinese mitten crab (Eriocheir sinensis) and is crucial for consumer satisfaction and the development of industry. In this study, we utilized fingerprints and the sensomics approach to analyze volatiles in the hepatopancreas of E. sinensis from Chongming and Taixing. GC-IMS indicated that the odor profile was dominated by pungent (-), buttery (+), and fruity (+) from Chongming and was more prone to alcoholic (-), solvent (-), and aldehydic (+) in Taixing. Moreover, PLS-DA modeling identified 2-acetylthiazole and toluene as the primary differential compounds. Subsequently, fifteen active-aroma compounds with FD values of >4 was recombined in an odorless matrix to simulate the odor profile of the hepatopancreas. Notably, removing methional may significantly decrease the intensity of the fatty and toasted odors. The findings reveal the odor profile of hepatopancreas and establish a theoretical foundation for subsequent studies on flavor.

Thermal aggregation behavior of silver carp myofibrillar protein at low salt content: Effect of oat β-glucan combined with ultrasound-assisted heating

The effects of oat β-glucan (OG) combined with ultrasound-assisted treatment on thermal aggregation behavior of silver carp myofibrillar protein (MP) under low salt concentration were investigated. The particle size and turbidity of MP were increased to higher levels by OG participation or ultrasound treatment during the two-stage heating. Both OG and ultrasonic treatment promoted the unfolding of MP structure, evidenced by the gradual decrease of α-helix content and fluorescence intensity, as well as the increase of β-sheet content, surface hydrophobicity and sulfhydryl content. Compared to solely OG or ultrasonic treatment, the combination of OG and ultrasound further promoted the unfolding of MP and more sulfhydryl groups were exposed in the pre-heating stage, which was conducive to strengthen the chemical forces between MP molecules. Additionally, AFM analysis revealed that the apparent morphology of the OG combined with ultrasonic treated group exhibited a smoother surface and a more uniform distribution of aggregates.

Structural and aggregation changes of silver carp myosin induced with alcohols: Effects of ethanol, 1,2-propanediol, and glycerol

This study investigated the effects of ethanol, 1,2-propanediol, and glycerol on the structure and aggregation behavior of silver carp (Hypophthalmichthys molitrix) myosin. All alcohols induced extensive alteration in the tertiary structure of myosin. Both ethanol and 1,2-propanediol further promoted an increase in the content of β-sheets in myosin and induced myosin aggregation. While glycerol had almost no impact on the secondary structure of myosin. Molecular dynamics simulations revealed that increasing the concentration of ethanol and 1,2-propanediol affected the overall structural changes in the myosin heavy chain (MHC), while glycerol exerted a more pronounced effect on the MHC tail when compared to the MHC head. Disruption of the hydration layers induced by ethanol and 1,2-propanediol contributed to local structural changes in myosin. Glycerol at a concentration of 20% induced the formation of a larger hydration layer around the MHC tail, which facilitated the stabilization of the protein structure.

Interaction of pepper numbing substances with myofibrillar proteins and numbness perception under thermal conditions: A structural mechanism analysis

This study examined the interaction between myofibrillar proteins (MPs) and the numbing substance hydroxy-α-sanshool (α-SOH) in a thermal environment, and provided an explanation of the numbness perception mechanism through muti-spectroscopic and molecular dynamics simulation methodology. Results showed that addition of α-SOH could reduce the particle size and molecular weight of MPs, accompanied by changes in the tertiary and secondary structure, causing the α-helix of MPs transitioned to β-sheet and β-turn due to the reorganization of hydrogen bonds. After a moderate heating (60 or 70 °C), MPs could form the stable complexes with α-SOH that were associated with attachment sites and protein wrapping. The thermal process might convert a portion of α-SOH' into hydroxy-β-sanshool' (β-SOH'). When docking with the sensory receptor TRPV1, the RMSD, RMSF and binding free energy all showed that β-SOH' demonstrated a low affinity, thereby reducing the numbing perception. These findings can provide a theoretical foundation for the advanced processing of numbing meat products.

Exploring the binding mechanisms of thermally and ultrasonically induced molten globule-like β-lactoglobulin with heptanal as revealed by multi-spectroscopic techniques and molecular simulation

This work employed the model protein β-lactoglobulin (BLG) to investigate the contribution of microstructural changes to regulating the interaction patterns between protein and flavor compounds through employing computer simulation and multi-spectroscopic techniques. The formation of molten globule (MG) state-like protein during the conformational evolution of BLG, in response to ultrasonic (UC) and heat (HT) treatments, was revealed through multi-spectroscopic characterization. Differential MG structures were distinguished by variations in surface hydrophobicity and the microenvironment of tryptophan residues. Fluorescence quenching measurements indicated that the formation of MG enhanced the binding affinity of heptanal to protein. LC-MS/MS and NMR revealed the covalent bonding between heptanal and BLG formed by Michael addition and Schiff-base reactions, and MG-like BLG exhibited fewer chemical shift residues. Molecular docking and molecular dynamics simulation confirmed the synergistic involvement of hydrophobic interactions and hydrogen bonds in shaping BLG-heptanal complexes thus promoting the stability of BLG structures. These findings indicated that the production of BLG-heptanal complexes was driven synergistically by non-covalent and covalent bonds, and their interaction processes were influenced by processes-induced formation of MG potentially tuning the release and retention behaviors of flavor compounds.

Effects of hsian-tsao polysaccharide on myosin gel structure and its binding capacity to flavor compounds

Hsian-tsao polysaccharide (HTP) with preferable biological activities was explored to improve the gel qualities of surimi. This study investigated the effects of HTP (0-1.0 mg/mL) on structural changes, in vitro digestibility, and fishy odor binding capacity of heat-induced myosin gels (30 mg/mL). HTP promoted the unfolding of myosin structure with transitions from α- helixes to β-sheets, accompanied by the enhancement of hydrophobic bonds, hydrogen bonds, and non-disulfide covalent bonds dominated within gel networks. Moreover, HTP facilitated the formation of compact gel structures of myosin with superior elastic properties (G' > G'') and apparent viscosity, but without affecting the final in vitro digestibility. Moreover, the microstructure of gels markedly affected the adsorption rate of flavor compounds, with a lower adsorption rate obtained for myosin-HTP gels with compact gel networks embedded with evenly small cavities. Additionally, HTP affected the flavor-binding capacities of myosin gels by increasing hexanal and heptanal, but reducing nonanal and 1-octen-3-ol, in relation to the combined effects of myosin structural changes and newly formed gel networks. This work provides a new prospect for application of HTP to regulate the adsorption rate and binding capacity of myosin gels to fishy odors, critical for improvement of gel properties in surimi products.

Integrated 4D label-free proteomics and data mining to elucidate the effects of thermal processing on crisp grass carp protein profiles

The crisp grass carp (CGC; Ctenopharyngodon idellus C. et V.), known for its unique texture and flavour, is a culinary delicacy whose quality is significantly influenced by thermal processing. This study employed 4D label-free proteomics and data mining techniques to investigate the proteomic changes in CGC muscle tissue induced by various heating temperatures. CGC samples were subjected to a series of heat treatments at increasing temperatures from 20 °C to 90 °C. Proteins were extracted, digested, and analysed using high-resolution mass spectrometry. The proteomic data were then subjected to extensive bioinformatics analysis, including GO and KEGG pathway enrichment. We identified a total of 1085 proteins, 516 of which were shared across all the temperature treatments, indicating a core proteome responsible for CGC textural properties. Differential expression analysis revealed temperature-dependent changes, with significant alterations observed at 90 °C, suggesting denaturation or aggregation of proteins at higher temperatures. Functional enrichment analysis indicated that proteins involved in amino acid metabolism, glutathione metabolism, and nucleotide metabolism were particularly affected by heat. Textural analysis correlated these proteomic changes with alterations in CGC quality attributes, pinpointing 70 °C as the optimum temperature for maintaining the desired texture. A strong positive correlation between specific upregulated proteins was identified, such as the tubulin alpha chain and collagen alpha-1(IV) chain, and the improved textural properties of CGC during thermal processing, suggesting their potential as the potential biomarkers. This study offers a comprehensive proteomic view of the thermal stability and functionality of CGC proteins, delivering invaluable insights for both the culinary processing and scientific management of CGC. Our findings not only deepen the understanding of the molecular mechanisms underpinning the textural alterations in CGC during thermal processing but also furnish practical insights for the aquaculture industry. These insights could be leveraged to optimize cooking techniques, thereby enhancing the quality and consumer appeal of CGC products.

Exploring the interaction between myofibrillar proteins and pyrazine compounds: Based on molecular docking, molecular dynamics simulation, and multi-spectroscopy techniques

Flavor is one of the most important factors that affect consumers' preference for processed meat products. This study aimed to investigate effects of heating on interaction between myofibrillar proteins (MPs) and pyrazine compounds and understand the underlying mechanisms. A combination of multispectral, molecular docking, and molecular dynamics technologies was used to achieve study's aim. Results demonstrated that MPs underwent structural reconstruction and expansion during heating, which significantly altered surface hydrophobicity and SH content. MPs' zeta potential reduced from -7.29 to -10.47 when a short heating time. Additionally, a positive correlation was found between β-sheet content and ability of MPs to adsorb pyrazine compounds. Molecular docking analysis revealed 13 binding sites for pyrazines and MPs. Furthermore, amino acid residues and pyrazine compounds were found to interact by four different forms of forces, primarily van der Waals forces, carbon‑hydrogen bonds, alkyl groups, and π-alkyl groups. Obtained results demonstrated that adequate or optimized heat treatment could expose more binding sites, hence enhancing the binding of MPs to pyrazine compounds. This study may be used to better understand how structural changes in MPs during processing affect MPs' capacity to bind flavor substances, which can help improve flavor of processed meats to encourage their consumption.

Study on the Mechanism of Modified Cellulose Improve the Properties of Egg Yolk gel

Natural fiber is not suitable for modifying yolk gel as a modifier because of its large size and high compactness. In this study, two kinds of modified cellulose were selected to improve the thermal gel properties of yolk. The results showed that the two kinds of cellulose promoted the formation of ordered structure in yolk gel. The ordered gel network not only improved the texture properties and rheological properties, but also improved the water retention of yolk gel significantly. CMC and CNFC at the same concentration, the modification effect of CMC on yolk gel was better than CNFC because of its excellent dispersion. However, high concentration of CNFC (1.20-1.60%) disrupted the cross-linking and ordered structure formation of yolk protein, and the quality of gel was significantly reduced.

Unravelling the interaction between α-SOH and myofibrillar protein based on spectroscopy and molecular dynamics simulation

This work systematically investigated the dose-response interaction between hydroxy-α-sanshool (α-SOH) and pork myofibrillar proteins (MPs) via spectroscopy, molecular docking, and molecular dynamics simulation methods. Results showed that MPs bound with low α-SOH can enhance the surface hydrophobicity and particle size of MPs, whereas high concentrations were exactly the opposite. The main interaction force in α-SOH/MPs complex changed from hydrophobic to hydrogen bonding with increased α-SOH. α-SOH causes tryptophan quenching and bring about a red shift at low concentration, as well as to promote α-helix conversion into β-sheet in MPs. Simultaneously, molecular docking and dynamics simulations verified that hydrogen bonding and hydrophobic forces were the main contributors to α-SOH/MPs complex, indicating that the binding of α-SOH with MPs proceeded spontaneously with high intensity, in which TYR286 contributed the most significant energy. Therefore, revealing the binding mechanism of α-SOH and MPs can contribute to the deep processing of numbing meat products.

Binding of Selected Aroma Compounds to Myofibrillar Protein, Sarcoplasmic Protein, and Collagen during Thermal Treatment: Role of Conformational Changes and Degradation of Proteins

To investigate the effects of conformational changes and thermal degradation of myofibrillar protein (MP), sarcoplasmic protein (SP), and collagen (CO) on the binding ability for aroma compounds during heating. Using SDS-PAGE, HPLC, and LC-MS/MS, a consistent rise in the total concentration of peptides and free amino acids formed by the thermal degradation of proteins was observed. The surface hydrophobicity, total sulfhydryl content, particle size, and secondary structure content of proteins changed significantly over time. Furthermore, the aroma binding ability of proteins was determined by gas chromatography-mass spectrometry. The results revealed an increase in binding ability during 5 or 10 min of heating due to protein unfolding and the accumulation of degradation products. However, the binding ability decreased due to protein aggregation with prolonged heating. Notably, all proteins exhibited strong affinity toward (E)-2-octenal, (E,E)-2,4-decadienal, 2-methyl-3-furanthiol, and dimethyl trisulfide. The binding ability of MP and SP was similar but differed significantly from that of CO, which had lower binding ability for hexanal, (E)-2-octenal, (E,E)-2,4-decadienal, and dimethyl trisulfide compared to MP and SP.

Structural changes induced by ultrasound improve the ability of the myofibrillar protein to bind flavor compounds from spices

Effects of ultrasound (UT) treatments on the structural, physicochemical, and functional properties of myofibrillar proteins (MPs), as well as their ability to bind to flavor compounds from spices, were investigated. The results demonstrated that UT treatment enhanced surface hydrophobicity, SH content, and absolute ζ-potential value of the MPs. Atomic force microscopy analysis displayed formation of MPs aggregates with small particle size in the UT-treated MPs samples. Meanwhile, UT treatment could improve the emulsifying properties and physical stability of MPs' emulsion. Additionally, the MPs gel network structure and stability significantly improved following UT treatment. Changes in the structural, physicochemical, and functional properties enhanced the ability of MPs to bind to flavor substances from spices depending on the duration of UT treatment. Furthermore, correlation analysis showed that the ability of myristicin, anethole, and estragole to bind to MPs was highly correlated with surface hydrophobicity, ζ-potential value, and α-helix content of MPs. The results of this study may help in understanding the relationship between the changes in MPs properties during the processing of meat products and their ability to bind to flavors from spices, thereby improving flavors retention and taste of processed meat products.

Insight into the protein oxidation impact on the surface properties of myofibrillar proteins from bighead carp

The objective of this study was to elucidate the influence of oxidative modifications of myofibrillar proteins (MPs) on their surface properties. Oxidative modifications (deamination, formation of disulfide bonds and Schiff bases), particle size, net surface charge, and binding ability of volatiles (2-enthylfuran, 1-octen-3-ol, hexanal, and octanal) of oxidized MPs was measured. Molecular docking of volatiles with actomyosin was performed using Qvina-W program and the specific oxidative modifications (monoxidation and deamination) of MPs were determined using LC-MS/MS. Results showed that oxidation of Cys (forming sulfinic, sulfonic, sulfenic acid, and disulfide bonds), monoxidation of Ala, Lys, Glu, and Asn, and deamination of Lys changed the surface properties of oxidized MPs including enhanced surface hydrophobicity and decreased affinity to volatile compounds and water. Overall, this study gives evidence of how protein oxidation affects the properties of MPs and therefore deteriorates fish meat quality.

Effect of Thermal Processing on the Conformational and Digestive Properties of Myosin

Heat treatment affects the structural properties of meat proteins, which in turn leads to changes in their sensitivity to digestive enzymes, further affecting the nutritional value of meat and meat products. The mechanism of changes in the structure and digestive properties of myosin under different heating conditions were studied. An increase in heating temperature led to the exposure of internal groups to a polar environment, but to a decrease in the sturdy α-helix structure of myosin (p < 0.05). The results of tryptophan fluorescence verified that the tertiary structure of the protein seemed to be unfolded at 70 °C. Higher protein denaturation after overheating, as proven by the sulfhydryl contents and turbidity, caused irregular aggregate generation. The excessive heating mode of treatment at 100 °C for 30 min caused myosin to exhibit a lower degree of pepsin digestion, which increased the Michaelis constant (Km value) of pepsin during the digestion, but induced the production of new peptides with longer peptide sequences. This study elucidates the effects of cooking temperature on the conformation of myosin and the change in digestibility of pepsin treatment during heating.

Understanding interactions among flavor compounds from spices and myofibrillar proteins by multi-spectroscopy and molecular docking simulation

Influence of the constant heating treatment on structural and adsorption properties of myofibrillar proteins (MPs) of chicken was investigated. The results showed that heat treatment enhanced the exposure of sulfhydryl groups and improved hydrophobicity of MPs surface. Particle size distribution of MPs significantly varied depending on heat treatment duration. Also, heat treatments resulted in significant changes in the α-helix and β-sheet structures of MPs. Besides, the MPs formed larger, irregular, and cluster-like aggregates after heat treatments. Moreover, heat treatments increased viscosity and surface roughness of MPs, while zeta potential value was reduced after heat treatments. Furhthermore, binding interactions between the MPs and spices flavors signifcanlty varied relying on nature of MPs and flavor compounds, as well as heat treatments duration. Amino acid residues were interacted with flavor compounds of spices via a variety of bonds and a stable MPs-flavors complex was performed. The obtained results provide a basis for understanding structural and physicochemical changes that occur in MPs during cooking and the interactions between MPs and flavors of spices.

Physicochemical, structural, functional and flavor adsorption properties of white shrimp (Penaeus vannamei) proteins as affected by processing methods

Proteins contribute to the flavor release and texture of foods besides their nutritional attributes. However, processing affects the protein structural conformation and, thus, their functional properties. White shrimp proteins (WSP) are well known for their nutritional and functional properties and limited attention has been paid to the flavor adsorption properties of WSP. This study investigated the effects of processing methods such as microwave drying, hot air drying, roasting, and boiling on the structural (secondary and tertiary) changes and physicochemical, functional, and flavor adsorption properties of white shrimp proteins (WSP). Structural changes of WSPs were evaluated by Fourier Transform Infrared (FTIR) spectroscopy, fluorescence spectroscopy, and sulfhydryl bond content. Results revealed that the processing triggered structural changes that affected the functional properties of WSP. The highest surface hydrophobicity (H₀) of WSP in boiling (58.27 ± 1.68) and microwave drying (39.83 ± 0.83) caused increased emulsifying properties and decreased water solubility. The increased content of α-helix and random coils leads to cross-linking and protein aggregation in hot air drying (21.62 ± 0.37 %) and roasting (24.30 ± 0.24 %), which leads to low H₀ and high foaming properties. Processing has increased the flavor adsorption ability of WSP. Among all the processing methods, boiling has shown the highest flavor adsorption potential, followed by microwave drying. The findings broaden the scope of techno-functional properties of WSP in the food industry by thermal treatment modification.

Evaluation of the adsorption capacity and mechanism of soy protein isolate for volatile flavor compounds: Role of different oxygen-containing functional groups

Mechanism of soy protein isolate (SPI) adsorbing isomers of volatile flavor compounds (VFCs: 2-octanone, 1-octen-3-ol and octanal) were investigated by exploring the interaction between different oxygen-containing functional groups (OCF groups: carbonyl, alcohol hydroxyl and aldehyde group) and SPI in this study. VFCs made SPI aggregate into larger particle size, and an increase in β-sheet and β-turn was observed. Octanal has strongest binding capacity to SPI, followed by 1-octen-3-ol and 2-octanone. Fluorescence analysis revealed that static quenching occurred between the VFCs and SPI, which suggested that SPI-VFCs complex were formed. Double logarithmic Stern-Volmer indicated the strongest interaction between aldehyde group and SPI, which was proved by surface plasmon resonance. Finally, molecular docking results showed more hydrogen bonds between octanal and SPI. The results showed that aldehyde groups were more likely to interact with SPI than others, probably due to their tendency to form more hydrogen bonds.

Improvement of the gel properties and flavor adsorption capacity of fish myosin upon yeast β-glucan incorporation

The potential effects of yeast β-glucan (YG) on heat-induced gel properties, microstructure and flavor adsorption capacity of fish myosin at different NaCl concentrations were investigated in this study. The incorporation of YG significantly improved the texture properties, gel strength, water holding capacity (WHC), storage modulus and loss modulus of myosin gels, especially at a high salt level, whereas the whiteness declined. Furthermore, myosin gels containing YG displayed a more compact and ordered three-dimensional network structure, accompanied by the increasing immobilization of water in gels. The binding abilities of gels to selected flavor compounds at high salt content were inferior to those at the low salt content. Regardless of the salt level, YG addition boosted the flavor binding capacity of gels, which might be attributed to the unfolding of the protein conformation by exposing more flavor-binding sites, as well as the porous sponge structure of YG with unique adsorption capacity.

Pilot-Scale Ensilaging of Herring Filleting Co-Products and Subsequent Separation of Fish Oil and Protein Hydrolysates

In this study, ensilaging of herring (Clupea harengus) filleting co-products was taken from lab-scale to pilot scale (1500 L) while monitoring the protein degree of hydrolysis (DH) and lipid oxidation. Subsequently, the possibility of recovering fish oil and protein hydrolysates using batch centrifugation at different g-forces/times was investigated. Around 38% DH was recorded after 2-day pilot-scale ensilaging of herring co-products at ambient temperature (i.e., ~ 22 °C), which was similar to the DH found in lab-scale (40% after 2 days; 22 °C). The lipid oxidation marker 2-thiobarbituric acid reactive substances (TBARS) reached 20 µmole TBARS/kg silage after 2-day ensilaging. Centrifugation of the silage at 3000–8500 × g for 2–20 min revealed successful separation into fish oil and protein hydrolysates. Heat-treating the silage (85 °C; 30 min) prior to centrifugation resulted in significantly higher oil and hydrolysates recoveries; the same being true for increased g-force. At 8500 × g, the recovery of oil and hydrolysates were 9.7 and 53.0% w/w, respectively, from heat-treated silage, while recoveries were 4.1 and 48.1% w/w, respectively, from non-heat treated silage. At 4500 × g, being a more scalable approach, corresponding numbers were 8.2 and 47.1% (w/w) as well as 2.0 and 40.2% (w/w). The recovered fish oil contained 8% EPA and 11% DHA of total fatty acids. Free fatty acids (FFA), peroxide value (PV), p-anisidine value (p-AV), and total oxidation (TOTOX) values of oils were in the range of 4–7% (FFA), 3.6–3.7 meq/kg oil (PV), 2.5–4.0 (p-AV), and 9.9–11.1 (TOTOX), respectively, which were within the acceptable limits for human consumption specified by the GOED voluntary monograph. The recovered protein hydrolysates contained peptides in the molecular weight range 0.3–6 kDa (~ 37%) and 11–34 kDa (~ 63%). Also, the remaining solids contained 15–17% (w/w) protein, having 44–45% essential amino acids. Overall, the results suggest that herring co-product silage is a valuable source of fish oil and protein hydrolysates, paving the way for ensilaging based-biorefining of herring co-products into multiple products.

Study on the interactions between the screened polyphenols and Penaeus vannamei myosin after freezing treatment

The denaturation of proteins (particularly myosin) due to freezing can lead to the deterioration of Penaeus vannamei. The purpose of this study was to verify the antifreeze protective effects of polyphenols screened by a molecular docking technique, and to explore their interactions with myosin after freezing treatment. It was found that the screened polyphenols could significantly increase the freezing rate and unfreezable water content of shrimp paste. The results of fluorescence spectra indicated that the hesperetin to myosin quenching process included both dynamic and static quenching, and it was primarily bound to myosin through hydrophobic interactions; The quenching of myosin by both dihydroquercetin and mangiferin was static quenching, and they were bound to myosin mainly by hydrogen bonds and van der Waals forces; All three of these polyphenols had only one binding site on myosin. Surface hydrophobicity indicated that all four polyphenols were engaged in non-covalent binding (hydrophobic interactions) with myosin. Infrared spectra demonstrated that the addition of these four polyphenols significantly increased the α-helix content of myosin. They also reduced the myosin particle size, zeta potential, and protein degeneration degree. Scanning electron microscopy revealed that the four polyphenols reduced the degree of aggregation, while more uniformly distributing the myosin particles. These observations provide a basis for the screening of polyphenols and further research into the protective mechanism of polyphenols on frozen myosin.

Changes in Myosin from Silver Carp (Hypophthalmichthys molitrix) under Microwave-Assisted Water Bath Heating on a Multiscale

To further prove the advantages of microwave-assisted water bath heating (MWH) in low-value fish processing, the effects of different heating methods (two heating stage method, high temperature section respectively using MWH1, MWH2, MWH3, WH—water heating, MH—microwave heating) on secondary and tertiary myosin structures, SDS-PAGE, surface morphology, scanning electron microscopy (SEM), and particle size distribution were compared and analyzed. The findings revealed that MH and MWH aided in the production of gel formations by promoting myosin aggregation. Myosin from silver carps demonstrated enhanced sulfhydryl group and surface hydrophobicity after MWH treatment, as well as a dense network structure. The distribution of micropores becomes more uniform when the microwave time is increased. Actually, the total effect of microwave time on myosin is not substantially different. The correlation between particle size distribution and protein aggregation was also studied, in terms of time savings, the MWH of short microwave action is preferable since it not only promotes myosin aggregation but also avoids the drawbacks of a rapid warming rate. These discoveries give a theoretical foundation for understanding silver carp myosin under microwave modification, which is critical in the food industry.

Metabolomic Effects of the Dietary Inclusion of Hermetia illucens Larva Meal in Tilapia

Black soldier fly (Hermetia illucens) larvae meal have been used as feed protein supplements in fish feed, but few researches have investigated the metabolomic effects of Hermetia illucens larvae meal supplements. Therefore, the metabolic effects on Nile tilapia were investigated by replacing 5%, 10%, and 20% of the dietary soybean meal in the basal diet with Hermetia illucens larvae meal, respectively. This study shows that 20% H. illucens larvae meal feed could promote tilapia average daily gain of upto 5.03 ± 0.18 g (mean ± SEM). It was found that the tricarboxylic acid cycle efficiency was improved by activating the enzymes of mitochondrial isocitrate dehydrogenase, NAD-malate dehydrogenase, succinate dehydrogenase, pyruvate dehydrogenase, and α-ketoglutarate dehydrogenase, which then increased the output of ATP and NADH. Furthermore, amino acid and protein biosynthesis was boosted by enhanced glutamine synthetase and glutamate synthase. In particular, GSH increased with increased H. illucens larvae meal. Unsaturated fatty acid biosynthesis was stimulated by higher levels of fatty acid synthase and acetyl CoA carboxylase. Additionally, there was no significant change in lipase levels. Thus, the higher acetyl Co-A content was primarily involved in fatty acid biosynthesis and energy metabolism. Flavor substances, such as nonanal and 2-methyl-3-furanthiol, also accumulated with the addition of H. illucens larvae meal, which increased the umami taste and meat flavor. Additionally, the flavor of tilapia was improved owing to a decrease in trimethylamine content, which causes an earthy and fishy taste. This study uncovers a previously unknown metabolic effect of dietary H. illucens larvae meal on Nile tilapia.

Impact of cooking on the sensory perception and volatile compounds of Takifugu rubripes

Takifugu rubripes is well-known for its unique flavour but can also develop a putrid off-note. To eliminate off-note and promote desirable flavour, four cooking processes (boiling, steaming, microwave-heating and roasting) were explored to determine their effects on cooked T. rubripes. The temperature and water dynamics, physico-chemical properties were analysed and correlated with sensory qualities. The changes of centre temperature dynamics during cooking decreased the water mobility and led to varied sensory properties. Six out of ten orthonasal aroma attributes and four out of five mouthfeel attributes were significantly different among samples (p < 0.05). Based on partial least squares regression analysis, orthonasal aroma attributes "roasted" and "earthy/putrid fish" highly correlated with the volatile compounds generated from Maillard reaction and lipid oxidation, respectively; meanwhile mouthfeel attributes of chewy/fibre and tender/juicy were highly associated with water loss and moisture, respectively. This study provides insights for optimising cooking conditions to create desirable fish flavour.

Quantitative proteomics reveals the relationship between protein changes and off-flavor in Russian sturgeon (Acipenser gueldenstaedti) fillets treated with low temperature vacuum heating

This study aimed to reveal the molecular mechanisms associated with off-flavor generation in sturgeon fillets treated by low temperature vacuum heating (LTVH). Label-free quantitative proteomics was used to identify 120 favor-related proteins, 27 proteins were screened as differentially expressed for bioinformatics analysis. 17 of KEGG pathways were identified. Particularly, proteins involved in proteasome and peroxisome were highly correlated with off-flavor formation. They were primarily implicated in the structures of proteins, including binding and proteasome pathways. The results indicated that the LTVH reduced the binding sites by down-regulating protease and superoxide dismutase expression. LTVH increased the myofibrillar protein and sulfhydryl content and decreased the total volatile basic nitrogen and thiobarbituric acid reactive substance, which confirmed that protein oxidation was related to off-flavor. This proteomics study provided new insights into the off-flavor of sturgeon with LTVH, and proposed potential link between biological processes and off-flavor formation.

Investigation of molecular mechanisms of interaction between myofibrillar proteins and 1-heptanol by multiple spectroscopy and molecular docking methods

In this study, we investigated the interaction between myofibrillar proteins (MPs) and selected alcohols (1-pentanol, 1-hexanol, and 1-heptanol). Only 1-heptanol exhibited the binding ability to MPs, and the binding ability significantly increased with increasing protein concentration (p < 0.05). In addition, both static and dynamic quenching occurred during the interaction, with a red shift of the maximum absorption peak in the synchronous fluorescence spectra indicating a change in the microenvironment of the MPs. The results of circular dichroism measurements suggested that the interaction between MPs and 1-heptanol altered the secondary structure of the MPs. Furthermore, thermodynamic analysis showed that hydrogen bonding and van der Waals forces dominated the interaction between MPs and 1-heptanol, which was confirmed by the results of molecular docking/dynamics simulations. This study provides an in-depth understanding of the interaction between MPs and alcohols, which can help to improve the flavor control in meat.

Insight into the evolution of aroma compounds during thermal processing of surimi gel from silver carp (Hypophthalmichthys molitrix)

This study aimed to investigate the formation of odor properties in surimi products by exploring changes in aroma compounds and their precursors at setting (40 °C) and gelling (90 °C) stages during surimi gel formation by solvent-assisted flavor evaporation, gas chromatography-mass spectrometry, and ultra performance liquid chromatography. Results revealed a gradual increase in the contents of most aldehydes, alcohols, and phenolics during surimi gel formation, while a decrease in the contents of (E)-2-pentenal, (E)-2-hexnenal, (Z)-4-heptenal, (E)-2-heptenal, and most ketones at gelling stage. During thermal process, 50 % decrease was observed in the contents of some unsaturated fatty acids (palmitoleic acid, oleic acid, etc.), and the contents of tyrosine, phenylalanine, methionine, isoleucine, and leucine decreased significantly (P < 0.05) at gelling stage. Moreover, lipoxygenase activity reached 4.19-4.81 U/min·g at setting stage. Overall, amino acid degradation and lipid auto-oxidation mainly occurred at gelling stage to promote the formation of related compounds.

Effects of high-pressure treatment on the muscle structure of salmon (Salmo salar)

High pressure (HP) is a non-thermal treatment that is generally used to reduce the microbiological contamination of food products, such as Atlantic salmon (Salmo salar). However, HP is known to alter the stability of proteins and can therefore affect the quality of salmon flesh. In this study, the effects of HP treatment for 5 min at 200, 400 and 600 MPa on the structure of Atlantic salmon were investigated. Transversal histological sections revealed a decrease in the fibre size from 200 MPa associated with an expansion of the extracellular spaces. Connective tissue was found to be modified from 400 MPa, resulting in an increase in its surface area. Fourier transform infrared (FT-IR) microspectroscopy revealed a reduction in the α-helix content and an increase in the aggregated β-sheet structure content with increasing pressure, reflecting a change in the secondary structure of proteins from 200 MPa.

Effects of ultrasound-assisted vacuum tumbling on the oxidation and physicochemical properties of pork myofibrillar proteins

The present research aimed to investigate the effects of high-intensity ultrasound (HIU, 20 kHz, 0 W, 100 W, 300 W and 500 W)-assisted vacuum tumbling (UVT) for 60 min and 120 min on the oxidation and physicochemical properties of the pork myofibrillar proteins (MPs). Compared with the vacuum tumbling (VT) groups without the HIU assistance, the carbonyl content increased, while the total sulfhydryl (SH) content was reduced with the increase of HIU power and treatment time (P < 0.05). The reactive SH content was increased significantly after treated by UVT with 300 W compared with the VT group (P < 0.05) regardless of the treatment time. Similarly, the surface hydrophobicity (S₀), the intrinsic tryptophan intensity, and the solubility in the UVT group (300 W) were remarkably higher than those of the VT group (P < 0.05). In contrast, the α-helix content and the particle size of MPs significantly decreased when the HIU power was at 100 W and 300 W (P < 0.05). The results suggest that UVT treatment could change the structure and physicochemical properties of MPs accompanied by protein oxidation.

Identification of the main aroma compounds in Chinese local chicken high-quality meat

Chicken meat flavor has deteriorated with the increase of meat production. With the aim to identify the main aroma compounds in chicken meat, 972 Chinese local chickens are used to analyze the volatile organic compounds (VOCs) in meat by gas chromatography-mass spectrometry analysis. The results revealed that various VOCs present in the meat belong to aldehyde, alcohol and alkane classes. Total aldehyde content is highest in breeds significantly negatively correlated with the content of the other two classes, and their flavor can be distinguished by E-nose. Also, 9 common VOCs were shared by different breeds. Furthermore, principal component analysis identified hexanal and 1-octen-3-ol as the major VOCs according to the three classes, 9 common VOCs, or all VOCs as a whole in each breed, respectively. This study identified the main aroma VOCs in chicken meat, which could serve as a basis for breeding chickens with improved meat flavor.

Effects of different ultrasound frequencies on the structure, rheological and functional properties of myosin: Significance of quorum sensing

Structure and rheological properties of myosin in myofibrillar protein (MP) after single frequency pulsed ultrasound (SFPU, G1-G2) and dual frequency pulsed ultrasound (DFPU, G3) were compared for the first time. Results showed SFPU and DFPU induced "stress response" through the action of cavitation on multiple myosin. In addition, there may be a certain quorum sensing among myosin, inducing a more stable β-antiparallel structure to resist negative effects of cavitation force. Results of particle size and synchronous fluorescence indicated that structure of myosin in MPs changed through stress. The increase in pH also assisted in the ultrasound process (G5-G7). Notably, DFPU induced stronger quorum sensing and formed a more stable structure. More so, effects of (-)-epigallocatechin-3-gallate (EGCG) and baicalein (BN) on the emulsion and gel properties of DFPU treated and non-treated MPs were also investigated. Results showed that ultrasound increased the stability of emulsion. Additionally, the texture and expressible moisture content (EMOC) of the gel were also improved after treatment.