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A new freshwater cultivation species, crisp grass carp (CGC; Ctenopharyngodon idellus C. et V.) has a special texture and is popular with consumers; thus, we should pay close attention to its storage conditions and bacterial degradation. CGC and grass carp (GC; Ctenopharyngodon idellus) were commercialized as fillets and subsequently stored at 4 an...
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Context 1
... culture was used to estimate the TVC, psychrotrophic bacteria, and Pseudomonas spp. during the storage period for both GC and CGC fillets at 4 and 88C (Figs. 1 through 3). CG and CGC came from the same fish farm and the same fish processing facility, and the initial microbial loads of the GC fillets and CGC fillets amounted to 4.43 and 4.21 log CFU g À1 fillets, respectively. ...
Context 2
... structure and some cold-resistant compounds (14). It was observed that Pseudomonas spp. lagged behind the psychrotrophic bacteria and TVC initially. Growth FIGURE 1. TVC changes of the GC and CGC fillets stored at 4 and 88 C. curves of Pseudomonas spp. in the fillets of both species were flat at first and became steep after 2 days of storage (Fig. 3). It has been proven that gram-negative bacteria, such as Pseudomonas spp. and Shewanella spp., grow on chilled fish in aerobic conditions, whereas P. phosphoreum and lactic acid bacteria are dominant in fish in anaerobic conditions (11). Pseudomonas spp. could survive in a cold environment because of the structure of their cell ...
Citations
... The improved textural qualities of the CGC have garnered significant consumer appeal. Despite extensive research into the textural characteristics and gut microbiota of CGC throughout its farming cycle (Li et al., 2018), there is a notable lack of scientific understanding regarding how heat treatment affects CGC crispness. Thermal processing markedly affects the organoleptic properties of fish products, including texture, flavor, and aroma, thereby influencing consumer acceptance and preferences (Lin et al., 2016;Xu et al., 2020). ...
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.
... During the chilled storage, the TVC values of the tea polyphenol-treated fish were lower than the controls at all time points (1-2 log CFU g −1 ). After 6 days, the TVC in the control increased to 7.32 log CFU g −1 and reached the maximum limit of acceptable microbial count after 6 days, as reported in previous reports [16]. In contrast, the TVC value for the fish fillets treated with the tea polyphenols was 7.09 log CFU g −1 after 12 days ( Figure 1). ...
We investigated the effects of tea polyphenol treatments on the quality and microbiota of crisp grass carp fillets during cold storage at 4 °C. Changes in the total viable count (TVC) and total volatile base nitrogen (TVB-N) of fillets were measured. The microbiota of the crisp grass carp was analyzed using high-throughput sequencing technique. The results indicated that tea polyphenol treatments inhibited bacterial growth and reduced TVB-N values of fish fillets, and subsequently extended their shelf life by 6 days. The high-throughput sequencing result showed that Pseudomonas was the most abundant bacteria in tea polyphenol-treated fish fillets at the end of shelf life, while Pseudomonas and Aeromonas were the most abundant bacteria in control samples. These findings suggested that tea polyphenol treatments could be used in future to extend the shelf life of crisp grass carp fillets and alter the bacterial communities responsible for spoiling fish.
... Therefore, depending on the purpose of the study, one or more variable regions were selected for separation to obtain more accurate sequencing results. This method was mainly applied to study the microbial diversity in raw meats (Benson et al., 2014;Fougy et al., 2016), fish (Hovda, Sivertsvik, Lunestad, Lorentzen, & Rosnes, 2007;Li, Pan, & Shen, 2018), and fermented meat products (Hu, Zhou, Xu, Li, & Han, 2009;Połka, Rebecchi, Pisacane, Morelli, & Puglisi, 2015). In addition, this method has also been applied to the study of an individual bacterial genus in different kinds of meats (Azwai et al., 2016;Xu, Anyogu, Ouoba, & Sutherland, 2010). ...
This study systematically investigated the dynamic changes in bacterial communities in roast chicken in normal and modified atmosphere packaging (MAP). The samples were stored under normal atmosphere and 40%/60% CO2/N2 MAP conditions for 28 days at 4 °C. Changes in the number and type of microorganisms in roast chicken during storage were defined via cultural and 16S rDNA sequencing techniques. More Bacteroides, Chryseobacterium, Lactobacillus, and Acinetobacter than other bacteria were initially found in roast chicken. With normal packaging, Pseudomonas rapidly multiplied and became the main spoilage organism in roast chicken after 7 days, with a relative abundance of >90% of the entire bacterial flora. With MAP, due to the high salt content, Halomonas became the main spoilage organism in roast chicken by the middle of the storage period (14 days). Between days 21 and 28 of storage, Pseudomonas gradually became the main spoilage organism in roast chicken, but its relative abundance was much lower in MAP than in normal packaging, followed by Lachnospiraceae (NK4A136 group) and Altererythrobacter. Our research shows that the microbes in roast chicken mainly originated from the processing environment and operators. The combination of MAP with a low storage temperature could effectively improve the quality and safety of roast chicken meat.
Practical Applications
This research showed the dynamic changes in the bacterial community of roast chicken stored under normal and modified atmosphere packaging (MAP). Microorganisms in roast chicken are mainly obtained from the processing environment and operators. Combining MAP with storage at low temperatures can effectively improve the quality and safety of roast chicken.
Most edible films/coatings including those made of gelatin cannot be used independently as packaging films. In this study, active fish gelatin-based bilayer packaging films were developed and applied to preserve Japanese sea bass. The coating method was applied to produce polylactic acid/tilapia fish gelatin-sodium alginate bilayer film (PLA/FGSA). β-cyclodextrin inclusion complexes of cinnamaldehyde (β-CD-CI) and thymol (β-CD-Ty) were added into the gelatin-based layer of the PLA/FGSA to obtain active bilayer films (PLA/FGSA-CI and PLA/FGSA-Ty). This combination improved the oxygen and water vapor barrier abilities of the films, compared with PLA and edible gelatin-based monolayer films. Both active bilayer films possessed strong antibacterial and antioxidant activities. PLA/FGSA-Ty film showed the most effective inhibition against the growth of Pseudomonas.spp and H2S-producing Shewanella, generation of total volatile basic nitrogen (TVB-N) and thiobarbituric acid reactive substances (TBARS) of fish meat. These results indicate the active bilayer films are promising in the preservation of seafood.
Suansun is a typical fermented bamboo shoot product widely consumed in southern China. Complex microorganisms are involved during spontaneous fermentation of suansun. However, little is known about the succession and roles of these microbiota throughout the fermentation process, especially for the functional microbiota involved in aroma formation. Thus, in this study, the dynamic changes in physicochemical parameters, flavor compounds, and microbiota community during the natural production of suansun were investigated. The principal component analysis (PCA) results showed that physicochemical parameters and flavor compounds varied substantially during the 30-day fermentation. Moreover, the microbial flora exhibited a dynamic change from the acid-sensitive genera of Lactococcus, Leuconostoc, Weissella, and Enterobacter to an acid-resistant genus of Lactobacillus due to lactic acid and acetic acid accumulation. Furthermore, bidirectional orthogonal partial least squares (O2PLS) indicated that four bacterial genera, namely, Lactobacillus, Clostridium_sensu_stricto_1, Enterobacter, and Leuconostoc, showed strong connections with various characteristic flavors, thus playing crucial roles in the unique flavor formation of suansun. These results may shed light on the development of effective starter cultures for the industrial manufacture of high-quality suansun products.
This study was conducted to evaluate the microbiota composition and quality changes of the tiger puffer (Takifugu rubripes) during 4°C refrigerated storage and ice storage for 14 days. The results showed that the sensorial shelf life of refrigerator-stored and ice-stored tiger puffer was 6 and 12 days, respectively. Macroccus and Kocuria were dominant microbiota in fresh fish fillets. Pseudomonas became dominant in refrigerated fillets on day 6, while its dominance was largely weakened in the ice-stored group. At the end of storage, Pseudomonas and Carnobacterium became dominant microbiota in the refrigerated group, while Carnobacterium was inhibited in the ice-stored condition. Furthermore, total viable counts, color, texture, sensory evaluation, K-value and related values, and biogenic amines of puffer fillets in the two groups showed that the quality gradually deteriorated during the storage, and puffer fillets in the ice-stored group decayed slower than that in the refrigerator-stored group. In conclusion, ice storage inhibited the growth of Pseudomonas and Carnobacterium. It also can inhibit the increase of K-value and related values, which was beneficial to the maintenance of fish fillet quality and thereby extended the shelf life of the tiger puffer when compared with refrigerated storage.
Paocai is a widely consumed Chinese traditional fermented vegetable product. To understand the effect of temperature on paocai fermentation flora, the bacterial community structure of paocai fermented at 10 °C, 15 °C, 25 °C and 35 °C was analyzed by culture-dependent and culture-independent methods. The results showed that increasing the fermentation temperature in a certain range is beneficial for rapid paocai acid production and shortening of the maturity period. Illumina Miseq sequencing was performed on 56 samples at different fermentation process temperatures using a culture-independent method. A total of 1,964,231 high-quality reads of 16S rRNA V3-V4 regions were obtained, and they were divided into 405 operational taxonomic units (OTUs) and identified as 213 bacterial genera. The bacterial diversity decreased with the progression of fermentation, and some spoiled samples had an increased diversity. The culture-independent method found that at 10 °C, Lactococcus appeared at the start of fermentation, Leuconostoc and Weissella appeared in the middle of fermentation, and Lactobacillus and Leuconostoc dominated fermentation in the late stage. At 15 °C, Lactococcus started fermentation, Leuconostoc appeared in the middle stage, and Lactobacillus was dominant in the late stage. At 25 °C, Lactococcus started fermentation, Weissella and Lactobacillus appeared in the middle stage, and Lactobacillus dominated fermentation in the late stage. Finally, at 35 °C, Lactococcus, Weissella, and Lactobacillus started fermentation, Weissella and Lactobacillus appeared in the middle stage, and Lactobacillus dominated fermentation in the late stage. A total of 647 strains of bacteria were isolated by culture-dependent methods and were divided into 12 genera and 19 species by randomly amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) and 16S ribosomal RNA gene (rDNA) sequencing technology. More types of bacteria were isolated in the early stage of fermentation. At 10 °C, Lactococcus lactis began fermentation, and Lactobacillus brevis and Leuconostoc mesenteroides dominated acid production in the middle and late stages of paocai fermentation. At 15 °C, L. lactis initiates fermentation, while Lactobacillus plantarum dominates the acid fermentation of paocai. At 25 °C and 35 °C, there were a large number of Enterobacteriaceae bacteria in the start-up fermentation stage, and L. plantarum was dominant after 1-2 days of fermentation. Redundancy analysis (RDA) found that the lower the temperature, the more bacterial species that are produced, and the higher the temperature and the longer the time, the more obvious are the effects of L. plantarum on paocai. The results of dominant bacteria studied by culture-dependent and culture-independent methods are similar. The results indicate that most of the dominant microorganisms in the paocai fermentation system are culturable. This discovery can provide data and physical support for modernization and regulation of different types of paocai production.
