Binding and distribution regularity of water molecules in high-moisture textured Antarctic krill (Euphausia superba) meat.

High-moisture extrusion technique with the advantage of high efficiency and low energy consumption is a promising strategy for processing Antarctic krill meat. Consequently, this study aimed to prepare high-moisture textured Antarctic krill meat (HMTAKM) with a rich fiber structure at different water contents (53 %, 57 %, and 61 %) and to reveal the binding and distribution regularity of water molecules, which is closely related to the fiber structure of HMTAKM and has been less studied. The hydrogen-bond network results indicated the presence of at least two or more types of water molecules with different hydrogen bonds. Increasing the water content of HMTAKM promoted the formation of hydrogen bonds between the water molecules and protein molecules, leading to the transition of the ß-sheet to the α-helix. These findings offer a novel viable processing technique for Antarctic krill and a new understanding of the fiber formation of high-moisture textured proteins.

Metabolic profiles and protein expression responses of Pacific oyster (Crassostrea gigas) to polystyrene microplastic stress.

The underlying toxicity mechanisms of microplastics on oysters have rarely been explored. To fill this gap, the present study investigated the metabolic profile and protein expression responses of oysters to microplastic stress through metabolomics and biochemical analyses. Oysters were exposed to microplastics for 21 days, and the results indicated that the microplastics induced oxidative stress, with a significant decrease in SOD activity in the 0.1 mg/L exposure group. Metabolomics revealed that exposure to microplastics disturbed many metabolic pathways, such as amino acid metabolism, lipid metabolism, biosynthesis of amino acids, aminoacyl-tRNA biosynthesis, and that different concentrations of microplastics induced diverse metabolomic profiles in oysters. Overall, the current study provides new reference data and insights for assessing food safety and consumer health risks caused by microplastic contamination.

Assessment of Multifunctional Activity of a Postbiotic Preparation Derived from Lacticaseibacillus paracasei Postbiotic-P6.

Postbiotics possess various functional activities, closely linked to their source bacterial strains and preparation methods. Therefore, the functional activities of postbiotics need to be evaluated through in vitro and in vivo methods. This study aims to prepare a postbiotic and explore its antihemolytic, anti-inflammatory, antioxidant, and antibacterial activities. Specifically, a postbiotic preparation named PostbioP-6 was prepared by intercepting 1-5 kDa of Lacticaseibacillus paracasei Postbiotic-P6 fermentation broth. The results demonstrate that PostbioP-6 exhibited notable biological activities across multiple assays. It showed significant antihemolytic activity, with a 4.9-48.1% inhibition rate at 10-50% concentrations. Anti-inflammatory effects were observed both in vitro, where 8-40% PostbioP-6 was comparable to 259.1-645.4 µg/mL diclofenac sodium, and in vivo, where 3.5 and 4.0 µL/mL PostbioP-6 significantly reduced neutrophil counts in inflamed zebrafish (p < 0.05). Antioxidant properties were evident through increased reducing power (OD700 increased from 0.279 to 2.322 at 1.25-12.5% concentrations), DPPH radical scavenging activity (38.9-92.4% scavenging rate at 2.5-50% concentrations), and hydroxyl radical scavenging activity (4.66-10.38% scavenging rate at 0.5-4% concentrations). Additionally, PostbioP-6 demonstrated antimicrobial activity against two Gram-positive bacteria, eight Gram-negative bacteria, and one fungus. Furthermore, PostbioP-6 significantly inhibited the increase in peroxide value and malondialdehyde content in cookies, highlighting its potential application in food preservation. In conclusion, we prepared a novel postbiotic, termed PostbioP-6, which proved to have prominent anti-hemolytic, anti-inflammatory, antioxidant, and broad-spectrum antimicrobial activities. The multifunctional properties of PostbioP-6 position it as a potentially effective functional food supplement or preservative. In the future, further research is necessary to elucidate the precise mechanisms of action, identify the active components, and validate its biological activities in animal models or clinical trials.

Effect of cytochrome c release on the mitochondrial-dependent apoptosis and quality deterioration of black rockfish (Sebastes schlegelii) postmortem storage.

Apoptosis was associated with decreased sensory quality attributes of fish during postmortem storage. Based on cytochrome c (cyt-c) release plays a crucial role in apoptosis, the study aims to investigate the factors regulating cyt-c release and whether cyt-c acts as an endogenous pro-oxidant to trigger lipid oxidation. Within 12 h postmortem, dramatic changes in the intramuscular environment (glycogen from 1.57 mg/g to 0.65 mg/g; ATP reduced by 92.91%; pH value reaching the lowest (pH = 7.14)) and the mitochondrial environment (accumulation of mitochondrial ROS and Ca2+ levels) are induced mitochondrial swelling and opening of the MPTP (increased 34.35% and 31.91%), leading to the release of cyt-c from the mitochondria into the cytoplasm and the activation of caspase-3. This leads to lipid oxidation and degradation of myofibrillar proteins, accelerating quality deterioration in color and texture. The results suggest that cyt-c is involved in lipid oxidation during postmortem through the apoptotic mitochondrial pathway.

A mechanistic investigation into combined influences of NaCl and extrusion temperature on fibrous structures of high-moisture textured yeast protein.

NaCl and extrusion temperature have an important influence on the qualities of high-moisture textured proteins, but the influence mechanism is still unclear. Therefore, this study prepared high-moisture textured yeast protein (HMTYP) with different NaCl contents (0%-4%) under different extrusion temperatures (170 °C, 180 °C) and characterized their physicochemical properties. The results showed that the HMTYP containing 1% and 2% NaCl prepared at 180 °C contained a strong fibrous structure. The possible mechanism was as follows: YP could not be sufficiently melted at 170 °C after adding NaCl, causing a decrease in the structural strength; however, at 180 °C, YP still reached a fully molten state even though 1%-2% NaCl was added. After YP sufficiently melted, NaCl enhanced the cross-linking and aggregation of proteins during cooling, which improved the textural properties of HMTYP. Accordingly, NaCl and extrusion temperature could combine to adjust the fibrous structure and texture of HMTYP.

Impact of frozen storage on physicochemical parameters and quality changes in cooked crayfish.

Customers are increasingly opting for ready-to-eat and easy-to-prepare food products, such as cooked crayfish. It is highly valued for its unique taste, tender meat, and nutritional properties. Therefore, we conducted an investigation into its quality parameters over an 8-week period at -20 °C. Parameters such as water distribution, oxidation reactions, color, microstructure, texture properties, and physicochemical parameters were examined. The physicochemical results indicated that as the storage time increased, the levels of pH and TVB-N (total volatile basic nitrogen) showed a significant increase, while the water holding capacity decreased significantly (P < 0.05). After two months of frozen storage, the carbonyl content and TBARS (thiobarbituric acid reactive substances) increased to 4.15 ± 0.16 nmol/mg protein and 1.6 ± 0.00 mg/kg, respectively. Additionally, the total sulfhydryl content decreased to 4.91 ± 0.10 mol/105 g protein, which had an impact on the quality of the crayfish. Electron microscopy revealed that with increasing storage time, the fiber structure gradually deteriorated due to water crystallization, leading to severe damage and breakage of muscle fibers. Interestingly, these changes related to storage affected color and texture parameters, thereby influencing the overall quality of the crayfish.

Preliminary Purification and Partial Characterization of a Functional Bacteriocin of Lacticaseibacillus paracasei Zhang and Mining for its Gene Cluster.

Bacteriocins produced by lactic acid bacteria (LAB) have good potential for use as food biopreservatives. Lacticaseibacillus paracasei Zhang (L. paracasei Zhang) is both a food use and a probiotic bacterium. This study aimed to purify and preliminary characterize the active antibacterial metabolite of L. paracasei Zhang. The cell-free supernatant of L. paracasei Zhang was collected and purified by ultrafiltration and gel filtration chromatography. The 1-3 kDa active fraction could inhibit the growth of Staphylococcus aureus but not Escherichia coli. Further antibacterial activity assays revealed its capacity to suppress various foodborne and human opportunistic pathogens (including Staphylococcus aureus, Pseudomonas fluorescens, Pseudomonas aeruginosa, Listeria monocytogenes, and Bacillus cereus), but not fungi. The antibacterial activity showed good tolerance to heat (40 to 100 °C), acid-base (pH 2-3 and pH 6-10), and digestions by a number of industrial and animal/human enzymes (such as trypsin, pepsin, α-amylase, and protease K, except papain); these desired properties make it a suitable biopreservative to be used in harsh and complex industrial production processes. The high papain sensitivity suggested a proteinaceous/peptide nature of the bioactivity. Moreover, our genomic data mining for bacteriocin through BAGEL4 revealed an area of interest encoding a complete set of putative genes required for bacteriocin production. In conclusion, our study showed that L. paracasei Zhang can produce extracellular functional antibacterial metabolite, likely a class II bacteriocin. Our preliminary extraction and characterization of the active metabolite demonstrated that it has good potential to be used as a biopreservative or an agent for suppressing gastrointestinal infections.

Temperature effects on plasmalogen profile and quality characteristics in Pacific oyster (Crassostrea gigas) during depuration.

The quality of Pacific oyster (Crassostrea gigas) can be affected by many factors during depuration, in which temperature is the major element. In this study, we aim to determine the quality and plasmalogen changes in C. gigas depurated at different temperatures. The quality was significantly affected by temperature, represented by varying survival rate, glycogen content, total antioxidant capacity, alkaline phosphatase activity between control and stressed groups. Targeted MS analysis demonstrated that plasmalogen profile was significantly changed during depuration with PUFA-containing plasmalogen species being most affected by temperature. Proteomics analysis and gene expression assay further verified that plasmalogen metabolism is regulated by temperature, specifically, the plasmalogen synthesis enzyme EPT1 was significantly downregulated by high temperature and four plasmalogen-related genes (GPDH, PEDS, Pex11, and PLD1) were transcriptionally regulated. The positive correlations between the plasmalogen level and quality characteristics suggested plasmalogen could be regarded as a quality indicator of oysters during depuration.

The inhibition mechanism of PostbioYDFF-3 on quality deterioration of refrigerated grass carp fillets from the perspective of endogenous enzyme and microorganisms changes.

The protective mode of PostbioYDFF-3 (referred to as postbiotics) on the quality stability of refrigerated fillets was explored from the aspects of endogenous enzyme activity and the abundance of spoilage microorganisms. Compared to the control group, the samples soaked in postbiotics showed significant reductions in TVC, TVB-N and TBARS values by 39.6%, 58.6% and 25.5% on day 5, respectively. In addition, the color changes, biogenic amine accumulation and texture softening of the fish fillets soaked in postbiotics were effectively suppressed. Furthermore, the activity of endogenous enzyme activities was detected. The calpain activities were significantly inhibited (p < 0.05) after soaking in postbiotics, which declined by 23%. Meanwhile, high throughput sequencing analysis further indicated that the growth of spoilage microorganism such as Acinetobacter and Pseudomonas were suppressed. Overall, the PostbioYDFF-3 was suitable for preserving fish meat.

Both viable Bifidobacterium longum subsp. infantis B8762 and heat-killed cells alleviate the intestinal inflammation of DSS-induced IBD rats.

In view of the safety concerns of probiotics, more and more attention is paid to the beneficial effects of dead probiotics cells. Herein, we investigated and compared the alleviation effects of viable Bifidobacterium longum subsp. infantis B8762 (B. infantis B8762) and its heat-killed cells on dextran sodium sulfate (DSS)-induced inflammatory bowel disease (IBD) rats. Four groups of rats (n = 12 per group) were included: normal control, DSS-induced colitis rats without bacterial administration (DSS), DSS-induced colitis rats with viable B. infantis B8762 administration (VB8762), and DSS-induced colitis rats with dead B. infantis B8762 administration (DB8762). Our results showed that both VB8762 and DB8762 administration exerted significant protective effects on DSS-induced IBD rats, as evidenced by a reduction in mortality, disease activity index score, body weight loss, as well as decreased histology score, which were companied by a significant decrease in serum pro-inflammatory factors compared with DSS group, and a stronger effect on modulating the fecal microbiota alpha-diversity and beta-diversity compared with DSS group. Additionally, the fecal metabolome results showed that both VB8762 and DB8762 interventions indeed altered the fecal metabolome profile and related metabolic pathways of DSS-induced IBD rats. Therefore, given the alleviation effects on colitis, the DB8762 can be confirmed to be a postbiotic. Overall, our findings suggested that VB8762 and DB8762 had similar ability to alleviate IBD although with some differences. Due to the minimal safety concern of postbiotics, we propose that the postbiotic DB8762 could be a promising alternative to probiotics to be applied in the prevention and treatment of IBDs.IMPORTANCEInflammatory bowel disease (IBD) has emerged as a global disease because of the worldwide spread of western diets and lifestyles during industrialization. Up to now, many probiotic strains are used as a modulator of gut microbiota or an enhancer of gut barrier to alleviate or cure IBD. However, there are still many issues of using probiotics, which were needed to be concerned about, for instance, safety issues in certain groups like neonates and vulnerable populations, and the functional differences between viable and dead microorganisms. Therefore, it is of interest to investigate the beneficial effects of dead probiotics cells. The present study proved that both viable Bifidobacterium longum subsp. infantis B8762 and heat-killed cells could alleviate dextran sodium sulfate-induced colitis in rats. The findings help to support that some heat-killed probiotics cells can also exert relevant biological functions and can be used as a postbiotic.

Changes in Flavor-Related Biomarkers in Pacific Oysters (Crassostrea gigas) Following Microplastic Exposure.

Microplastics have been an emerging threat to filtering species and the ingestion and impacts of microplastics on oysters are a cause for concern. However, much remains unknown about the effects of microplastics on flavor-related biomarkers in oysters. Herein, a laboratory microplastic exposure with concentrations of 1, 10, and 100 mg/L for 15 days was performed to investigate the impacts of microplastics on the flavor parameters of oysters. Exposure to microplastics changed the odor characteristics of oysters. Microplastic exposure had minor effects on the fatty acid composition; however, significant alterations in free amino acids and nucleotides were observed under the 1 and 10 mg/L exposure groups, respectively. The overall results indicated 10 mg/L of microplastic exposure significantly increased the equivalent umami value of oysters. These findings stressed the effects of microplastics on oysters and would be an important reference for the assessment of the potential risks associated with microplastics in marine edible species.

Antibacterial and antibiofilm activities of protocatechualdehyde and its synergy with ampicillin against methicillin-resistant Staphylococcus aureus.

Protocatechualdehyde (PA) is a phenolic acid present in many plants and has many biological activities. Herein, the antagonistic effects and the action mechanism of PA against methicillin-resistant Staphylococcus aureus (MRSA) were studied. The results showed that PA had both significant antibacterial and anti-biofilm activities against MRSA. Additionally, PA had synergy with ampicillin against MRSA. It was elucidated that PA was prominent in destroying cell membranes, increasing cell membrane permeability and intracellular ROS production, thus leading to bacterial cell damage. Transcriptome analysis showed that PA disrupts many physiological pathways, including increasing cell membrane permeability, inhibiting biofilm formation, decreasing resistance to antimicrobial agents, and impairing DNA replication. Finally, the antimicrobial preservation test showed that PA could inhibit the growth of MRSA and prevent the corruption of beef. In summary, PA is an effective natural antibacterial substance and has a good application potential in food preservation, even in tackling antibiotic resistance problems.

The influence of γ-PGA on the quality of cooked frozen crayfish during temperature fluctuations.

The purpose of this study was to compare the influences of gamma-poly glutamic acid (γ-PGA) (1, 2, 3, and 4 %) to see which could outperform conventional cryoprotectant mixture (4 % sorbitol + 4 % sucrose) on cooked crayfish properties, such as physicochemical, textural qualities, oxidation reaction, water distributions, and microstructure integrity, during different freeze-thaw cycles. Crayfish quality characteristics improved significantly as γ-PGA concentration increased compared to control samples.Adding γ-PGA 4 % reduced the carbonyl content from 4.20 to 3.00 nmol/ mg protein during fluctuation-1 (F1), and from 4.15 to 2.80 nmol/ mg protein during fluctuation-2 (F2) compared to control samples. Furthermore, it increased the total sulfhydryl content from 4.15 and 4.76 to 6.19 and 6.47 mol/105 g protein during F1 and F2 and after five freeze-thaw cycles (FTC). This suggests that this concentration was more effective at controlling protein changes than other concentrations. γ-PGA generally enhanced the water-holding capacity by preventing protein denaturation and limiting ice crystal recrystallization. As a result, microstructure stability was evident, texture degradation was avoided, and the crayfish's color was preserved.

In-Depth Analysis of the Mechanism of Astaxanthin Succinate Diester in Reducing Ulcerative Colitis in C57BL/6J Mice Based on Microbiota Informatics.

This paper aims to explore the effect and mechanism of water-soluble astaxanthin succinate diester (Asta-SD) on ulcerative colitis (UC) induced by dextran sodium sulfate in zebrafish and C57BL/6J mice. Asta-SD was synthesized with hydrophilic fatty acid succinic anhydride and the hydroxyl groups at the ends of F-Asta were synthesized by esterifying. Through the construction of a zebrafish intestinal inflammation model, it was found that Asta-SD could effectively reduce the levels of ROS and increase the number of healthy intestinal lysosomes in zebrafish. After continuous gavage of Asta-SD for seven days, the body weight, disease activity index, colonic length, colonic histopathology, expression of inflammatory factors, and intestinal flora of the mice were measured. The results showed that Asta-SD could significantly alleviate weight loss and colonic shrinkage, as well as reducing pro-inflammatory cytokines and recess injury in UC mice. The 16S rRNA gene sequencing showed that Asta-SD significantly increased the beneficial bacteria (Lactobacillus, Anaerotruncus) and decreased the relative abundance of pathogenic bacteria, effectively maintaining intestinal microbiota homeostasis in mice. Based on Pearson analysis, Bacteroides, Parabacteroides, and Butyrimionas were expected to be associated with the significant difference in the expression of inflammatory factors between the UC and the corresponding host. Thus, Asta-SD significantly improves UC and maintains intestinal microbiota homeostasis.

Effects of liquid nitrogen freezing at different temperatures on the quality and flavor of Pacific oyster (Crassostrea gigas).

This study aimed to evaluate the effects of different liquid nitrogen freezing (LNF) temperatures (-20, -40, -60, -80, and -100 °C) on the water holding capacity, texture, microstructure, and flavor of Crassostrea gigas (C. gigas). The results showed that -40 °C LNF, -60 °C LNF, and -80 °C LNF improved the water holding capacity of C. gigas (P < 0.05); -60 °C LNF and -80 °C LNF could effectively maintain the hardness of the body trunk and adductor muscles. Compared with -20 °C refrigerator freezing (RF), the LNF group could form smaller ice crystals and thus reduce the damage to the muscle cell structure damage, especially LNF at -80 °C. Gas chromatography-ion mobility spectrometry (GC-IMS) and e-nose results indicated that -80 °C LNF maintained the flavor profile of few aldehydes and alcohols compared to other freezing groups. Therefore, -80 °C LNF effectively improved the quality and maintain the flavor characteristics of frozen C. gigas.

A Europium Nanosphere-Based Time-Resolved Fluorescent Immunochromatographic Assay for the Rapid Screening of 4,4'-Dinitrocarbanilide: Aiming at Improving Strip Method Performance.

Considering that the strip method is simple and convenient for users, a Europium nanosphere-based time-resolved fluorescent immunochromatographic assay (TRFICA) for the rapid screening of 4,4'-dinitrocarbanilide (DNC) was developed to improve the performance of strip assays. After optimization, TRFICA showed IC50, the limit of detection, and cut-off values of 0.4, 0.07, and 5.0 ng mL-1, respectively. No significant cross-reactivity (CR < 0.1%) with 15 DNC analogs was observed in the developed method. TRFICA was validated for DNC detection in spiked chicken homogenates, and recoveries ranged from 77.3% to 92.7%, with coefficients of variation of <14.9%. Moreover, the time needed for the detection procedure, including the sample pre-treatment, was less than 30 min for TRFICA, which had never been achieved before in other immunoassays. The newly developed strip test is a rapid, sensitive, quantitative, and cost-effective on-site screening technique for DNC analysis in chicken muscle.

An overview of microplastics in oysters: Analysis, hazards, and depuration.

Microplastic pollution has become an emergent global environmental issue because of its ubiquitous nature and everlasting ecological impacts. In marine ecosystems, microplastics can serve as carriers to absorb various contaminants and the ingestion of microplastics in oysters is of concern because they can induce several adverse effects. The analytical process of microplastics in oysters commonly consists of separation, quantification, and identification. Quantification of microplastics is difficult since information regarding the analytical methods is incoherent, therefore, standard microplastic analytical methods for shellfish should be established in the future. The depuration process can be used to reduce the level of microplastics in oysters to ensure safe consumption of oysters and longer depuration time facilitates improved depuration efficacy. In summary, this review aims to help better understand microplastic pollution in oysters and provide useful suggestions and guidance for future research.

The Interaction in Electrolyte Additives Accelerates Ion Transport to Achieve High-Energy Non-Aqueous Lithium Metal Batteries.

Electrolyte engineering is a feasible strategy to realize high energy density lithium metal batteries. However, stabilizing both lithium metal anodes and nickel-rich layered cathodes is extremely challenging. To break through this bottleneck, a dual-additives electrolyte containing fluoroethylene carbonate (10 vol.%) and 1-methoxy-2-propylamine (1 vol.%) in conventional LiPF6 -containing carbonate-based electrolyte is reported. The two additives can polymerize and thus generate dense and uniform LiF and Li3 N-containing interphases on both electrodes' surfaces. Such robust ionic conductive interphases not only prevent lithium dendrite formation in lithium metal anode but also suppress stress-corrosion cracking and phase transformation in nickel-rich layered cathode. The advanced electrolyte enables Li||LiNi0.8 Co0.1 Mn0.1 O2 stably cycle for 80 cycles at 60 mA g-1 with a specific discharge capacity retention of 91.2% under harsh conditions.

Flexible solar cells based on foldable silicon wafers with blunted edges.

Flexible solar cells have a lot of market potential for application in photovoltaics integrated into buildings and wearable electronics because they are lightweight, shockproof and self-powered. Silicon solar cells have been successfully used in large power plants. However, despite the efforts made for more than 50 years, there has been no notable progress in the development of flexible silicon solar cells because of their rigidity1-4. Here we provide a strategy for fabricating large-scale, foldable silicon wafers and manufacturing flexible solar cells. A textured crystalline silicon wafer always starts to crack at the sharp channels between surface pyramids in the marginal region of the wafer. This fact enabled us to improve the flexibility of silicon wafers by blunting the pyramidal structure in the marginal regions. This edge-blunting technique enables commercial production of large-scale (>240 cm2), high-efficiency (>24%) silicon solar cells that can be rolled similarly to a sheet of paper. The cells retain 100% of their power conversion efficiency after 1,000 side-to-side bending cycles. After being assembled into large (>10,000 cm2) flexible modules, these cells retain 99.62% of their power after thermal cycling between -70 °C and 85 °C for 120 h. Furthermore, they retain 96.03% of their power after 20 min of exposure to air flow when attached to a soft gasbag, which models wind blowing during a violent storm.

Application of multi-omics combined with bioinformatics techniques to assess salinity stress response and tolerance mechanisms of Pacific oyster (Crassostrea gigas) during depuration.

Depuration is a vital stage to ensure the safety of oyster consumption, and salinity had a great impact on the environmental adaptability of oysters, but the underlying molecular mechanism was poorly understood during depuration stage. Here, Crassostrea gigas was depurated for 72 h at different salinity (26, 29, 32, 35, 38 g/L, corresponding to ±20%, ±10% salinity fluctuation away from oyster's production area) and then analyzed by using transcriptome, proteome, and metabolome combined with bioinformatics techniques. The transcriptome showed that the salinity stress led to 3185 differentially expressed genes and mainly enriched in amino acid metabolism, carbohydrate metabolism, lipid metabolism, etc. A total of 464 differentially expressed proteins were screened by the proteome, and the number of up-regulated expression proteins was less than the down-regulated, indicating that the salinity stress would affect the regulation of metabolism and immunity in oysters. 248 metabolites significantly changed in response to depuration salinity stress in oysters, including phosphate organic acids and their derivatives, lipids, etc. The results of integrated omics analysis indicated that the depuration salinity stress induced abnormal metabolism of the citrate cycle (TCA cycle), lipid metabolism, glycolysis, nucleotide metabolism, ribosome, ATP-binding cassette (ABC) transport pathway, etc. By contrast with Pro-depuration, more radical responses were observed in the S38 group. Based on the results, we suggested that the 10% salinity fluctuation was suitable for oyster depuration and the combination of multi-omics analysis could provide a new perspective for the analysis of the mechanism changes.