This study evaluated the spoilage potential of dominant bacteria (Shewanella putrefaciens and Pseudomonas fluorescens) on the effect of the deterioration of adenosine triphosphate-related compounds in refrigerated large yellow croaker fillets under air-packaging and modified atmosphere packaging (MAP). In this work, the total viable count (TVC), adenosine triphosphate-related compounds, and related enzyme activities were characterized in refrigerated large yellow croaker fillets inoculated spoilage bacteria. Macrogenomic analysis was employed to explore the contribution of packaging methods to metabolic pathways and related enzymes. The result demonstrated that the TVC of S. putrefaciens reached 7.85 (lg (CFU/g)) on day 21, exhibiting stronger potential for growth in MAP. The results showed that S. putrefaciens had a higher potential to degrade adenosine triphosphate-related compounds and produce related enzyme activities under MAP conditions than P. fluorescens. The initial value of hypoxanthine riboside (HxR) during storage in the air processing (AIRP) group was 0.76 μmol/g, which reached a peak on day 3 (1.71 μmol/g), and the level of HxR decreased to 0.38 μmol/g on day 12. The MAP group showed a similar trend to the AIRP group, but the peak appeared later than the AIRP group. The ability to degrade HxR in S. putrefaciens exhibited a significant difference in air packaging. In addition, macrogenomic analysis indicated that the degradation of inosine monophosphate (IMP) was primarily performed by 5'-nucleotidase (5'-NT). This study enhances our comprehension of the role of microorganisms in fish spoilage and provides valuable insights for the development of novel preservation methods.

Ulcerative colitis (UC) is a chronic, relapsing inflammatory bowel disease with a poorly defined etiology. Traditional fermented foods may serve as a potential source of therapeutic agents for UC, which can be applied as probiotics. Lactiplantibacillus plantarum HBM1, a strain with high gastrointestinal fluid tolerance, was isolated from fermented foodsoriginating from Bama, a longevity village. This study investigated its potential to alleviate intestinal barrier dysfunction and inflammation in both in vitro and in vivo UC models. We identified a fat-soluble component less than 3 kDa (FCLPS_l3000) from the HBM1 culture supernatant, and validated that it maintained tight junction protein expression and suppressesd pro-inflammatory cytokine release in an LPS-induced Caco-2/Raw264.7 co-culture UC model. Through combined analysis of transcriptomic and metabolomic analyses, we found that FCLPS_l3000 relieved barrier function damage and inflammation in the LPS-induced Caco-2/Raw264.7 cell co-culture model by regulating the TLR4/NLRP3/Caspase-1 axis. In animal experiments, we further confirmed that the improvement effects of FCLPS_l3000 and live HBM1 probiotics on DSS-induced UC were related to the TLR4/NLRP3/Caspase-1 axis. Additionally, FCLPS_l3000 and live HBM1 alleviated UC-induced neuronal damage and neuroinflammation, thereby improving accompanying secondary neurological dysfunction. Interestingly, FCLPS_l3000 demonstrated superior efficacy with live HBM1 across multiple indicators. Collectively, this work reveals novel active components and the underlying regulatory mechanisms of probiotic intervention for UC and underscores the therapeutic potential of probiotic derivatives. Our findings provide a new direction for the development of multi-target therapies for UC and associated neurological complications.

As a specific spoilage organism of seafood under refrigerated temperature conditions, Shewanella spp. tend to form biofilms that exacerbate the occurrence of seafood spoilage. Biofilm-promoting factor A (BpfA) has been reported to promote the adhesion and biofilm formation of Shewanella spp., but its role in adhesion and biofilm formation of S. putrefaciens under cold stress needs to be further investigated. To better comprehend the effect of BpfA on adhesion and biofilm formation of S. putrefaciens under cold stress (4 ℃), bacterial adhesion and biofilm phenotype of S. putrefaciens CN32 WT and ΔbpfA at 4 ℃ were analyzed and performed transcriptomics. The results showed that the deletion of bpfA had almost no effect on the growth of S. putrefaciens CN32 at 4 ℃, but weakened the unicellular adhesion capacity of S. putrefaciens CN32 and destabilized the stability of the multicellular adhesion layer. In addition, the biomass of the mature biofilm formed by ΔbpfA was merely around 50% of that observed in the mature biofilm of S. putrefaciens CN32 WT, the average thickness and volume of the biofilm decreased by 18% and 27%, respectively, and the composition of the biofilm changed. Transcriptome analysis demonstrated that the deletion of bpfA led to differential expression of genes involved in metabolic pathways such as bacterial chemotaxis, two-component system, tyrosine metabolism, drug metabolism-other enzymes and biofilm formation-Vibrio cholerae, which in turn influenced bacterial adhesion and biofilm formation. Those results advance our acknowledgment of the character of BpfA on adhesion and biofilm formation of S. putrefaciens CN32, which contributes to understanding bacterial adhesion and the control of biofilm formation.

Aquatic products are easily affected by microorganisms and endogenous enzymes during distribution, resulting in their quality deterioration. Non-thermal sanitization technology can maintain the nutritional value, delay the process of spoilage, prolong the shelf-life and enhance the commodity value of aquatic products. This review paper compares the principles and main characteristics of the common non-thermal sterilization technologies, describes the sterilization mechanism of cold plasma technology, and summarizes recent progress in its application in the quality improvement, bacterial decontamination, blackening inhibition, and safety control of aquatic products. Moreover, possible solutions to the problems of applying cold plasma technology alone are proposed, and future trends in the development of cold plasma technology are discussed. Through this review, we hope to provide a theoretical rationale for the application of this technology in the preservation of aquatic products.

The mechanism of action of ultrasound (US) combined with slightly acidic electrolyzed water (SAEW) treatment against Shewanella putrefaciens was studied. The spoilage causing bacterium Shewanella putrefaciens was treated with US, SAEW or US + SAEW for 10 min, and untreated cells suspended in sterile normal saline was used as a control. The changes in the cell membrane and internal environment of this bacterium were evaluated by measuring the reduction in bacterial count, bacterial growth curve, electrical conductivity, propidium iodide (PI) intake, alkaline phosphatase (AKP) and lactate dehydrogenase (LDH) activity, the leakage of ultraviolet-absorbing materials. The microstructure was also observed by scanning electron microscopy (SEM) before and after treatment. The results showed that US + SAEW treatment reduced the bacterial count by 2.48 (lg (CFU/mL)). Compared with the control and single treatment groups, US + SAEW greatly damaged the cell membrane integrity, causing the leakage of intracellular components and a significant increase in electrical conductivity, AKP and LDH activity (P < 0.05). After US + SAEW treatment, the bacterial cells collapsed obviously, the outer membrane was broken, the cell wall was damaged, and a large amount of cellular contents leaked out of the cells.Therefore, ultrasonic treatment can seriously damage the cell wall and cell membrane of Shewanella putrefaciens, promoting SAEW to enter into cells, enhancing the bactericidal efficacy, and leading to cell death eventually.

The effect and mechanism of light-emitting diodes (LED) blue light with different photosynthetic photon flux densities (10, 20 and 30 μmol/(m²·s)) combined with fennel essential oil (0.35 μL/mL) on the quality preservation of fresh-cut amaranth was studied. Four treatment groups: T1 (fennel essential oil alone), T2 (10 μmol/(m²·s) blue light + fennel essential oil), T3(20 μmol/(m²·s) blue light + fennel essential oil) and T4 (30 μmol/(m²·s) blue light + fennel essential oil) were designed as well as a control group without any treatment. The total bacterial count, physicochemical properties, antioxidant enzyme activity and sensory properties of each group were evaluated. The results showed that combined treatment with blue light (30 μmol/(m²·s)) and fennel essential oil (0.35 μL/mL) could maintain the contents of chlorophyll, ascorbic acid and soluble solids in amaranth well. The bacteriostatic effects of the four treatments could be ranked as follows: T4 > T3 > T2 > T1.Superoxide dismutase (SOD) and peroxidase (POD) activity of fresh-cut amaranth treated by 460 nm blue light and fennel essential oil were significantly higher than those in amaranth treated with fennel essential oil alone. The combined treatment effectively inhibited the accumulation of malondialdehyde (MDA) and nitrite in fresh-cut amaranth, significantly increased the sensory score, and extended the shelf life up to 10 days. Therefore, the combined treatment with LED blue light and fennel essential oil is an effective way to delay the senescence and preserve the quality of fresh-cut amaranth.

The effects of different inoculation methods of two dominant spoilage bacteria on the quality change in obscure pufferfish (Takifugu obscurus) during cold storage and their spoilage ability were evaluated. Sterile whole fish were inoculated with Pseudomonas fluorescens, Shewanella putrefaciens, or their combination. Samples treated with sterile water were taken as the control group. All samples were stored at 4 ℃. Microbial (total viable count, Pseudomonas bacteria count, and Shewanella bacteria count), physiochemical (pH, total volatile base nitrogen (TVB-N)) contents, K value, and xanthineoxidase (XOD) activity), and protein properties (total sulfhydryl (SH) content, myofibril fragmentation index (MFI), and intrinsic fluorescence intensity (IFI)) were measured at 2-day intervals during storage, and magnetic resonance imaging (MRI) was also carried out to analyze quality changes comprehensively. The spoilage ability of the dominant spoilage bacteria was evaluated by the yield factor of spoilage metabolite production. The results showed that total viable count, TVB-N contents and K value in the inoculation groups were higher than those of the control group. Inoculation with the spoilage bacteria accelerated protein oxidation and promote the breakage of myofibril, resulting in changes in the tertiary structure of fish proteins and a significant decrease in water content. Moreover, the rate of quality deterioration in the combined inoculation group was faster than that in the single inoculation groups. According to the results of the yield factor of spoilage metabolite production, the combined inoculum had the strongest spoilage ability, followed by S. putrefaciens, and P. fluorescens had the weakest spoilage ability.

In order to investigate the combined effects of ultrasound and slightly acidic electrolyzed water on the quality changes of vacuum-packaged sea bass (Lateolabrax japonicas) during refrigerated storage, fresh sea bass fillets were treated with ultrasonic (US) at 20 kHz and 600 W, slightly acidic electrolyzed water (SAEW), their combination (US + SAEW), or sterile water (as control) for 10 min and then stored in a refrigerator at 4 ℃. Total viable count (TVC), Psychrobacter count (PC), and physicochemical properties such as pH, total volatile base nitrogen (TVB-N) content, water migration, waterholding capacity (WHC)) and indicators lipid oxidation were measured every three days during storage. The results showed that the US and SAEW treatments inhibited the increase in TVC and PC during storage, and obviously slowed down the increase in pH and TVB-N content as compared to the control group. The US treatment greatly improved WHC. The SAEW treatment inhibited lipid oxidation in fish while improving WHC. Compared to the control group, the combined treatment provided the best quality preservation, and extended the shelf-life of refrigerated vacuum-packed sea bass by 6 days at least.

In order to investigate the protective effect of mango commercial packaging (wrapping paper and plastic net) and other packaging methods (gourd-like inflatable membrane and inflatable bag) on mangoes during transportation, Vietnamese green mangoes were subjected to simulated transportation experiments on a vibration table at 13 ℃ and 180 r/min for 24 hours, followed by storage at 13 ℃ for up to 20 days. The changes in yellowing rate, disease index, mass loss rate, moisture content and distribution, hardness, propectin and soluble pectin contents, respiration intensity, 1-aminocyclopropane-1-carboxylic acid synthase (ACS) level, relative conductivity, and the contents of titratable acid, total soluble solids (TSS) and vitamin C (VC) were measured during the storage period. The results showed that inflatable bag packaging significantly delayed the yellowing of mangoes and the occurrence of disease, reduced the losses of free water and mass, and decreased the peak values of respiratory intensity and ACS content. The slowest increase in relative conductivity and TSS content was observed for inflatable bag packaged mangoes during low-temperature transportation and storage. Wrapping paper packaging slowed down the rate of change in the contents of propectin and soluble pectin, plastic net packaging slowed down the rate of decrease in hardness and reduced VC loss, and gourd-like inflatable membrane packaging restrained the decrease in titratable acid content. Therefore, both kinds of commercial packaging and gourd-like inflatable membrane packaging had poor protective effects on mangoes during transportation, while inflatable bag packaging significantly reduced the damage caused by transportation to mangoes and maintain higher commodity characteristics of mangoes. These results provide a theoretical reference for mango cushioning packaging and postharvest storage and preservation technology.

This work was undertaken in order to study the combined treatment effects of ultrasound and caffeic acid on the quality of sea bass (Lateolabrax japonicas) during refrigerated storage. Fresh sea bass fillets were arbitrarily allocated into five groups: ultrasonic treatment at 20 kHz and 600 W for 10 min (US), dipping in 2.0 g/L caffeic acid for 10 min (CA), ultrasonic treatment at 20 kHz and 600 W for 5 min followed by dipping in 2.0 g/L caffeic acid for 5 min (US + CA), dipping in sterile water for 10 min (blank control, CK), and dipping in 1% acetic acid for 10 min (AA). After draining off the soaking solution, the samples were packed separately with polyethylene (PE) pouches, and then stored in a refrigerator at 4 ℃. Total viable count (TVC), physicochemical properties such as pH, total volatile basic nitrogen (TVB-N) content, thiobarbituric acid (TBA) value, texture profile analysis (TPA) parameters, and water-holding capacity (WHC), intrinsic fluorescence intensity (IFI) and sensory quality were measured every two days. The results showed that the US and CA treatments retarded the growth of TVC. On the fifth day, the TVC values in the CA and US groups were 18.49% and 15.53% lower than that in the control group, respectively. The increase of pH and TVB-N values in the treatment groups was obviously slower than that in the control group. On the 10th day of storage, the TVB-N content of the control group exceeded the spoilage limit, reaching (33.88 ± 0.56) mg/100 g compared to (16.71 ± 0.41) mg/100 g for the US + CA group. Both the US and CA treatments improved the WHC of fish greatly, while the CA treatment also had a stronger inhibitory effect on lipid oxidation in fish. Among the five groups, the US + CA group had the best overall quality. Compared with the CK group, the US + CA treatment maintained the quality better and extended the shelf-life of sea bass by four days at least.