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In this study, the quality changes of grass carp during tea polyphenol-assisted curing were studied from physicochemical and flavor perspectives. The addition of tea polyphenols has a positive effect on maintaining the water content of fish as the curing time increases (p < 0.05). The tea polyphenol-assisted treatment maintains the brightness of grass carp meat. The addition of tea polyphenols also slowed down the rate of pH growth and enhances the texture of grass carp (p < 0.05). The addition of tea polyphenols reduced His content, which had a positive effect on the taste of the cured grass carp products. When the pickling time reached 60 min, the inosine monophosphate content of tea polyphenol-treated groups was higher than that of the group soaked in salt only. Combined with equivalent umami concentration and taste activity values, it was found that the addition of 0.1% TP could improve freshness of grass carp cured products. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effects of flavourzyme addition on protein degradation and flavor formation in grass carp during fermentation. The related results showed that the addition of flavourzyme reduced the moisture content and accelerated the hydrolysis of protein and generation of water‐soluble flavor substances (e.g., TCA‐soluble peptides, α‐amino nitrogen, and free amino acids), thereby contributing to fermented grass carp products with a better taste quality. Besides, radar map results of electronic tongue and electronic nose showed that flavourzyme addition gives fermented products a more intense umami taste and odor. Meanwhile, sensory evaluation results also further confirmed that the addition of flavourzyme significantly improved the sensory attributes of fermented grass carp products, especially the taste and odor attributes. Overall, flavourzyme addition may be an effective way to shorten fermentation time and improve the flavor quality of fermented grass carp products during fermentation. Practical Applications: In this study, to study the effects of flavourzyme addition on protein degradation and flavor formation in grass carp during fermentation, the related indicators include the moisture content, total nitrogen, non‐protein nitrogen, protein degradation index, TCA‐soluble peptides, α‐amino nitrogen, free amino acids, electronic tongue, electronic nose, and sensory attributes were analyzed. This study may provide some useful information for the improvement of fermentation methods and the production of high‐quality fermented grass carp products. [ABSTRACT FROM AUTHOR]

Background: Enzyme injection is vital for improving the sensory attributes and processing characteristics of meat products by enhancing proteolysis. However, studies regarding the appropriate dose addition for accelerating protein degradation in grass carp are minimal. This study aimed to investigate the impact of Flavourzyme® on the flavor quality and antioxidant activity of salted grass carp via brine injection and brining. Results: Flavourzyme was added at doses of 0, 5, 10, 20, and 30 leucine aminopeptidase units (LAPU) per kilogram of raw meat. The results indicated that adding Flavourzyme promoted proteolysis, which was reflected by the enhanced total free amino acid content (from 3.7414 g kg−1 to 4.9160 g kg−1 in the brining group and from 3.8039 g kg−1 to 5.4061 g kg−1 in the injection group) and a decrease in salt soluble and insoluble protein (P < 0.05). The antioxidant activity was improved, and the thiobarbituric acid reactive substance value in salted carp decreased due to the higher content of the protein hydrolysis product (P < 0.05). All sensory attributes were improved significantly, especially when using brine injection (P < 0.05). Brine injection was helpful to diffuse the Flavourzyme, resulting in stronger proteolysis. Conclusion: The appropriate Flavourzyme dose was 10 LAPU kg−1 in the injection group and 20 LAPU kg−1 in the brining group. Therefore, moderate Flavourzyme addition was excellent in improving sensory attributes and storage characteristics, whereas injection represented a novel method to obtain a similar fish meat quality in a shorter time and with less added Flavourzyme. © 2021 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Summary: The aim of this study was to investigate the changes in physicochemical properties and myofibrillar protein properties of grass carp meat during brining and brine injection at 4 °C. The time reached equilibrium was 7 h in brining group and 5 h by injection, where the salt content was about 1.76%. The water content, water holding capacity and yield in injection group (86.59%, 9.18% and 110%, respectively) were higher than brining group (84.76%, 11.47%, and 108%, respectively) at equilibrium point significantly (P < 0.05). This was attributed to the more swollen filament lattices and disordered protein structure in injection group (P < 0.05). The myofibrillar protein structure was compared, including sulphydryl content, surface hydrophobicity, solubility, sodium dodecyl sulphate polyacrylamide gel electrophoresis pattern and secondary structure. The injection group presented the better quality of salted fish meat in shorter time. [ABSTRACT FROM AUTHOR]

In this study, the quality changes of grass carp fillets dried by microwave‐hot‐air combined drying under different microwave time were investigated. The salted fillets were dried at 385 W microwave with different time (0, 2, 4, 6, 8, and 10 min), followed by 65℃ hot air to the end. The quality of fillets was evaluated by drying time, color, hardness, rehydration ratio, and taste characteristics (ATP‐related compounds, free amino acids, E‐tongue taste profile, EUC, and TAV). Results showed that grass carp fillets dried by microwave‐hot‐air combined drying had better qualities compared with single hot‐air drying. Besides, microwave time had obvious effects on the quality changes of grass carp fillets, and 6 min was considered as the optimal drying time. [ABSTRACT FROM AUTHOR]

The research on the quality changes of grass carp during brine salting with 6%, 8%, and 10% salt additions was evaluated by chemical and physical indicators, as well as a sensory assessment and microbiological analysis. The NaCl content was proportional to salt addition and salting time. The increase of salt addition could lead to the increase of hardness and chewiness in which change trends were contrary to the pH within 24 hr. All K values were less than 10% during brine salting. The effect of 8% salt additions on free amino acids was relatively smaller. Higher levels of salt additions could inhibit bacterial growth. Combined with sensory assessment, equivalent umami concentration (EUC), and taste activity value (TAV) to analysis comprehensively, it was suggested that grass carp meat should be eaten at 4–8 hr of brine salting with 8% salt additions or processed for the next step, in which the grass carp meat had a better taste and quality. [ABSTRACT FROM AUTHOR]

This study was aimed at to investigate the quality changes of grass carp during short‐term starvation. The pH, lactic acid, free amino acid, and adenosine triphosphate‐related compounds of dorsal meat, belly meat and red meat in grass carp were measured during starvation for 6 days, and the quality of grass carp was evaluated by K value, equivalent umami concentration (EUC), taste activity value (TAV), and electronic tongue. The pH of three parts meat reached the maximum value on the fourth day, which was closely related to the lactic acid content. Concurrently, the contents of fresh sweet amino acids were higher on the fourth day in all parts. The K values in dorsal meat and belly meat were below 10% during starvation. Considering the overall results of electronic tongue, EUC, and TAV analysis, it is suggested that grass carp should be marketed and eaten with a starvation period of 2–4 days for best taste and quality. [ABSTRACT FROM AUTHOR]

Although grass carp is an important freshwater fish in the food industry, little is known about the changes that occur in its volatile components and its degree of freshness postmortem. These changes were, therefore, investigated in this study. including total volatile basic nitrogen (TVB-N), total viable counts (TVC), thiobarbituric acid-reactive (TBA) substances and lipase activity of the dorsal muscle of grass carp stored at 4 °C for postmortem up to 8 days. Volatile components were simultaneously quantified assessed using gas chromatography–mass spectrometry (GC–MS). Sensory assessment (SA) and electronic nose assessments were also performed. Results indicated that the level of TVB-N, TVC and TBA increased with storage time increase, reaching 16.92 mg/100 g, 5.37 log 10 CFU/g and 0.72 mg/100 g at 144 h, respectively. Lipase activity peaked on the first day of storage, and then began to decrease rapidly afterwards, reaching its minimum (34.76 ± 8.90 U/g prot) on the eighth day, suggesting the decrease in the freshness. While the SA had exceeded the acceptable limit by the sixth day. The number of volatile compounds increased with the prolongation of storage time. Relative olfactory activity value (ROAV) analysis showed that 9, 8, 8, 12, 12 and 9 predominant components were identified at 0 h, 24 h, 48 h, 96 h, 144 h and 192 h, respectively. The findings suggest that grass carp should be consumed within 6 days when stored at 4 °C, with the optimal edible time being 4 to 8 h after death. [ABSTRACT FROM AUTHOR]

The back cover image is based on the Original Article The impact of Flavourzyme on flavor, antioxidant activity and sensory attributes of salted grass carp by brine injection and brining by Shi Wenzheng et al., https://doi.org/10.1002/jsfa.11506. [ABSTRACT FROM AUTHOR]

• The prepared GMP particles have an irregular polyhedral structure. • The O/W type Pickering emulsion can be stabilized by GMP. • The increased concentration of GMP improves the stability of Pickering emulsions. In this study, edible Pickering emulsions stabilized with GMP particles were prepared for the first time using low-value grass carp myofibrillar protein (GMP). To elucidate the emulsion formation mechanism, the grass carp myofibrillar protein particles were first characterized, and the results showed that the lyophilized GMP particles had an irregular polyhedral structure and were amphiphilic nanoparticles. The stability of GMP-based emulsions tended to stabilize with the increase of GMP concentration at an appropriate oil-to-water volume ratio, with a decrease in droplet particle size and an increase in water-holding capacity, storage stability, and rheological stability, whereas the phenomenon of droplet aggregation after storage appeared at 4.0% additive level. Therefore, appropriate concentrations of GMP at a certain oil-to-water volume ratio can stabilize Pickering emulsions, which have an important future as a potential food-grade active substance delivery carrier for biological applications. [ABSTRACT FROM AUTHOR]

In this study, adenosine triphosphate (ATP)‐related compounds and free amino acids were determined to study the changes of water‐soluble flavor substances in grass carp meat during steaming for 18 min. Sensory assessment, electronic tongue, equivalent umami concentration (EUC) value, and taste active value (TAV) were also performed to obtain the best quality of steamed grass carp meat. The results showed that the flavor presented by nucleotides in three parts meat was better within 9 min. The bitter amino acids in the dorsal meat and red meat significantly decreased at 6 min (101.33 mg/100 g and 44.64 mg/100 g, respectively). From the sensory analysis, EUC value, and TAV, it can be found that the quality of grass carp meat was the best when steamed for 6–9 min. The electronic tongue indicated that the taste differences were significantly between 6 and 9 min. Therefore, this study suggested that grass carp should be eaten during 6–9 min of steaming. Practical applications: As the main way of meat processing and eating, heating not only endows the product with good color, but also kill microorganisms and improve the product quality. The reasonable heating will make the protein denaturation of the food, so that the protein digestion and absorption rate can be improved, which is conducive to people to obtain more abundant nutrition. The quality changes of grass carp meat during 18 min of steaming were studied by measuring ATP‐related compounds and free amino acids, combining with sensory assessment, electronic tongue analysis, EUC value, and TAV. These results not only provide useful information for the quality control of grass carp in the heating process, but also provide theoretical reference for the improvement of the nutritional value of grass carp. In addition, the mechanism of flavor change in the heating process of grass carp will be further improved, and effective suggestions will be provided for consumers to reasonably eat grass carp. [ABSTRACT FROM AUTHOR]

The cover image is based on the Full Article Study on changes in the quality of grass carp in the process of postmortem, by Hongli Wang et al., DOI 10.1111/jfbc.12683. [ABSTRACT FROM AUTHOR]

Grass carp is an important freshwater fish but little is known about its quality postmortem. We tracked changes in the pH, texture, lactic acid, ATP‐related compounds, K value, free amino acids (FAA) contents in grass carp stored at 4°C for 192 hr. Sensory and electronic tongue assessment were also performed. The results showed a consistent trend in the hardness and chewiness. pH were closely correlated with the lactic acid content and hardness. The fresh sweet amino acids gradually decreased with time while the opposite occurred with the bitter amino acids. The content of Hx and HxR increased gradually. The K value remained increased throughout the storage. Sensory assessment followed the opposite trend. The electronic tongue indicated that the differences were distributed in various areas between the first 2 days and the last 6 days. Overall, we recommend that grass carp should be consumed within 6 days when stored at 4°C. Practical applications: In fish, the process of quality change after death can normally be divided into four stages: the early biochemical change, rigidity and dissolving, self‐dissolution and finally, corruption. Rigidity can delay the process of corruption somewhat as fish in the rigid period are almost as fresh as newly caught fish. Preservation may thus be described as an extension of the period of rigor mortis. Postmortem changes in grass carp meat were studied over a period of 192 hr by measuring its pH, texture properties, lactic acid, ATP‐related compounds, K values, and FAA content. Sensory assessment and electronic tongue measurements were also conducted. In addition to establishing a theoretical basis for the quality control and processing of grass carp, these results provide useful information for manufacturers and product developers seeking to improve the quality of their grass carp products and will also provide farmers with valuable insights into quality retention. [ABSTRACT FROM AUTHOR]

This study examined the dorsal meat, belly meat, red meat, skin, intestines and gills of grass carp to determine the volatile compounds present in different parts using the monolithic material sorptive extraction gas chromatography–mass spectrometry and the electronic nose. Although the electronic nose was able to distinguish the flavors of the red meat, skin, intestines and gills, the dorsal and belly meat could not be differentiated. For dorsal meat, belly meat, red meat, fish skin, fish intestines and fish gills, 56, 55, 58, 67, 59, and 68 volatile compounds, respectively, were identified, the majority of which were aldehydes and alcohols. There were 9, 7, 9, 12, 7, and 9 predominant components were identified in dorsal meat, belly meat, red meat, fish skin, fish intestines, and fish gills. The fishy smell detected from strongest to weakest were: fish gills, fish intestines, fish skin, red meat, and dorsal meat/belly meat. Practical applications: Freshwater fish generally have an unattractive fishy, earthy odor thus not favored by consumers. The present study reveals volatile components present in different parts of grass carp using monolithic material sorptive extraction gas chromatography–mass spectrometry (MMSE–GC–MS) and electronic nose. The results demonstrated that combination of electronic nose response, principle component analysis, and MMSE–GC–MS can be applied to distinguish the flavors of the red meat, fish skin, fish intestines and fish gills, the dorsal meat and belly meat successfully and this method could be used for the identification of different compounds in similar gas chromatography–mass spectrometry analysis. The findings of this study will enrich our theoretical knowledge of flavor chemistry of fish products. [ABSTRACT FROM AUTHOR]

This study investigated the effect of rutin-grass carp myofibrillar protein (R-GMP) co-stable fish oil high internal phase emulsion on the quality of surimi gel compared with the direct addition of soybean oil. Combined with the stability, microstructure and rheological properties, R-GMP (GMP: 3.0%, rutin: 12%,/GMP, w/w) could form a stable O/W type high internal phase Pickering emulsion with an oil-water ratio of 0.75. The L*, a *, and b * values and whiteness of silver carp surimi gel were increased significantly (P < 0.05) after fish oil-based high internal phase emulsion was added as oil. Meanwhile, compared with the direct addition of soybean oil, the hardness, chewiness, gel strength and water-holding capacity of surimi gel were significantly enhanced (P < 0.05) after the addition of R-GMP high internal phase emulsion, and more free water was bound to the gel network. The microstructure showed that the R-GMP high internal phase emulsion could be evenly distributed in the dense and ordered protein network gel in the form of small oil droplets, while the direct addition of soybean oil would produce an aggregation of oil droplets and destroy the network structure of the gel. In conclusion, R-GMP stabilized fish oil high internal phase emulsion optimizes the gel quality of oil-enhanced surimi gel, providing new ideas for healthy fat replacement and the development of functional emulsified surimi products. [Display omitted] • A stable HIPE gel with R-GMP synergistic stabilization was constructed. • Compared with soybean oil, HIPE improved the gel strength and TPA of the surimi gel. • The free water content of surimi gel with HIPE was reduced, the WHC was enhanced. • The oil of small droplets in HIPE was evenly distributed in the surimi gel network. [ABSTRACT FROM AUTHOR]

[Display omitted] • A total of 45 volatile compounds were identified from naturally fermented grass carp. • 13 volatile compounds (OAV ≥ 1) were identified as the key volatile compounds. • Lactiplantibacillus contributed significantly to the volatile flavor formation during natural fermentation of grass carp. Complex microbial communities contribute significantly to the flavor formation of traditional fermented fish products. However, the relationship between microorganisms and flavor formation in traditional fermented grass carp products is still unclear. In this study, the diversity and succession of microbial communities and the variation of volatile compounds during natural fermentation of grass carp were analyzed using high-throughput sequencing of 16S rRNA and headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS), respectively. The core functional microorganism and key volatile compounds were identified, and their potential relationship was revealed using a correlation network model analysis. The microbial community analysis result showed that the microbial diversity during natural fermentation of grass carp decreased markedly with increasing fermentation time, and Lactiplantibacillus , Staphylococcus , and Enterobacter were the dominant genera in naturally fermented grass carp. HS-SPME-GC-MS analysis result showed that 45 volatile compounds were identified from fermented samples, among which 13 compounds (e.g., hexanal, heptanal, nonanal, decanal, 3-octanone, 3-methyl-1-butanol, 1-hexanol, 1-heptanol, 1-octen-3-ol, 1-octanol, ethyl acetate, 3-methyl-1-butanol acetate, and 2-methoxy-4-vinylphenol) were identified as the key volatile compounds. Additionally, the correlation network model analysis result revealed that Lactiplantibacillus showed significantly positive correlations with most of the key volatile compounds, making an important contribution to the formation of volatile flavor in naturally fermented grass carp. This study may lead to an understanding of the role of core functional microorganisms in the formation of volatile flavor during the natural fermentation of grass carp and provide some theoretical guidance for the industrial production of high-quality fermented grass carp products. [ABSTRACT FROM AUTHOR]

[Display omitted] • Rinsing could significantly affect the aroma profiles of grass carp mince. • HS-SPME-GC-MS identified 57 volatile compounds in grass carp mince. • HS-GC-IMS identified 20 volatile compounds in grass carp mince. • The washing sample with a weak alkaline solution has better sensory acceptability. The aroma characteristics of grass carp mince washed in four processes were analyzed via electronic nose (E-nose), headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS), headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS), and sensory analysis techniques. Significant differences were revealed in the E-nose and sensory analysis results of the aroma characteristics of grass carp mince samples washed via different washing processes, while fifty-seven volatile compounds (thirteen aldehydes, eighteen alcohols, two ketones, eighteen hydrocarbons, two aromatic compounds, one furan, and two other compounds) and twenty volatile compounds (five aldehydes, four ketones, six alcohols, four esters, and one acid) were identified via HS-SPME-GC-MS and HS-GC-IMS of the Raw and washed grass carp mince samples, respectively. All these techniques revealed that the types and relative contents of volatile compounds in the grass carp mince decreased significantly and differently after each of the four washing processes. Moreover, compared with the water and saline solution washing processes, washing with weak alkaline solution processes exhibited the most significant removal effect on the volatile compounds of grass carp mince. Besides, the sensory analysis results also showed that weak alkaline solution washing processes (washing twice with pure water and once with 0.3% sodium bicarbonate solution) may be most effective in removing fishy off-odor compounds and contributing to a better overall aroma profile in grass carp mince. The findings of this study may provide some basic knowledge for the rational screening of washing methods in the production of high-quality grass carp surimi. [ABSTRACT FROM AUTHOR]