Nucleotide degradation, biogenic amine level and microbial contamination as quality indicators of cold-stored rainbow trout (Oncorhynchus mykiss) gravad

Changes in physicochemical properties and taste quality of Patinopecten yessoensis adductor muscle during cold storage

In this study, three-step infrared spectroscopy (tri-step IR) in conjunction with liquid chromatography was employed to examine the alterations in the physicochemical properties and non-volatile taste constituents of scallop adductor muscles (AM) refrigerated at 4 °C over 0-9 days. The results revealed that in the early stage of refrigeration, there were negligible variations in terms of color and appearance. The total volatile basic nitrogen value exceeded the regulatory limit of 15 mg N/100 g on 5D. Taste profile analysis exhibited significant temporal variations. Specifically, the arginine (Arg) content decreased dramatically from 1048.74 mg/100 g to 5.06 mg/100 g, while adenosine monophosphate (AMP) decreased by 66.19 % and 90.02 % on 1D and 5D, respectively, leading to deteriorated taste quality. Hypoxanthine (Hx), and hypoxanthine riboside (HxR) demonstrated substantial impacts on bitterness. Notably, tri-step IR serve as a viable means of swiftly identifying the taste transformations of AM. This study furnishes a theoretical underpinning for consumers when partaking of scallop products.

Changes in flavor quality of marinated Chinese mitten crab (Eriocheir sinensis) with vacuum pack during cold storage

In order to study the pattern of changes in quality of marinated Chinese mitten crabs (Eriocheir sinensis) during cold storage, three aspects of sensory, taste and odor were investigated. Sensory evaluation and total volatile basic nitrogen (TVB-N) were measured in viscera and abdomen muscle at 0, 7, 15 and 30 days of storage at 4°C. Sensory scores significantly declined at 15 d, coinciding with TVB-N levels exceeding 25 mg N/100 g. Taste profiling demonstrated distinct changes over the storage period. Arginine (Arg) in viscera and abdomen muscle decreased by 18.16 % and 43.26 %, respectively, while adenosine monophosphate (AMP) dropped to 48.46 and 22.22 mg/100 g after 15 days, contributing to loss of umami. Based on the correlation analysis, it was known that bitterness was related to freshness, with tyrosine (Tyr), phenylalanine (Phe), hypoxanthine (Hx) and hypoxanthine riboside (HxR) being more significant contributors to the bitterness. Gas chromatography-ion mobility spectrometry (GC-IMS) analysis attributed late-stage undesirable odors to the production of aldehydes and ketones, particularly heptanone, 3-hydroxy-2-butanone, heptanal and glutaraldehyde. This study provided valuable guide for improving the flavor quality of Chinese mitten crabs in the field of prepared dish.

Insight into the correlation of key taste substances and key volatile substances from shrimp heads at different temperatures

This study aimed to investigate taste substances of shrimp heads stored at 20 °C, 4 °C, -3 °C, and - 18 °C, and the correlation between taste substances and 25 key volatile substances. Notably, samples stored at 20 °C showed significant changes in bitter amino acids and hypoxanthine, and quickly deteriorated. Samples stored at 4 °C for 14 d or - 3 °C for 30 d facilitated the development of umami amino acids, sweet amino acids, and IMP. Furthermore, samples stored at -18 °C for 30 d demonstrated no significant changes in taste profile. Changes in taste substances through quantitative analysis were consistent with changes in taste profile through e-tongue analysis. Based on the results of O2PLS (VIP > 1), Cys, Arg, Glu, Ser, Val, Ala, Ile, ADP, and IMP were correlated with 25 key volatile substances. This study provides fundamental data for the storage, transportation, and value-added utilization of shrimp heads.

Changes in the Quality and Microbial Communities of Precooked Seasoned Crayfish Tail Treated with Microwave and Biological Preservatives during Room Temperature Storage

The qualities of precooked foods can be significantly changed by the microorganisms produced during room temperature storage. This work assessed the effects of different antibacterial treatments (CK, without any treatment; microwave treatment, MS; microwave treatment and biological preservatives, MSBP) on the physicochemical properties and microbial communities of precooked crayfish tails during room temperature storage. Only the combination of microwave sterilization and biological preservatives significantly inhibited spoilage, as evidenced by the total viable count (4.15 log CFU/g) after 3 days of room temperature storage, which satisfied the transit time of most logistics companies in China. Changes in pH and TVB-N were also significantly inhibited in the MSBP group compared with those in the CK and MS groups. More than 30 new volatile compounds were produced in the CK groups during room temperature storage. However, in the MSBP groups, the volatile compounds were almost unchanged. The correlations between the microbial composition and volatile compounds suggested that specific bacterial species with metabolic activities related to amino acid, energy, cofactor, and vitamin metabolism, as well as xenobiotics biodegradation and metabolism, were responsible for the changes in volatile compounds. These bacteria included Psychrobacter, Arthrobacter, Facklamia, Leucobacter, Corynebacterium, Erysipelothrix, Devosia, Dietzia, and Acidovorax. Overall, our findings provide a foundation for the development of strategies to inhibit spoilage in precooked crayfish tails stored at room temperature.

Curcumin-mediated photodynamic treatment extends the shelf life of salmon (Salmo salar) sashimi during chilled storage: Comparisons of preservation effects with five natural preservatives

The impact of curcumin-mediated photodynamic treatment (PDT) on the microbiological, physicochemical and sensory qualities of salmon sashimi has not been explored. Herein, this study aimed to evaluate the effects of PDT on the shelf-life quality of ready-to-eat salmon fillets during chilled storage (4 °C) in comparison with five widely investigated natural extracts, including cinnamic aldehyde, rosmarinic acid, chlorogenic acid, dihydromyricetin and nisin. From a microbial perspective, PDT exhibited outstanding bacterial inhibition, the results of total viable counts, total coliform bacteria, psychrotrophic bacteria, Pseudomonas spp., Enterobacteriaceae family, and H2S-producing bacteria were notably inactivated (p < 0.05) to meet the acceptable limits by PDT in comparison with those of the control group and natural origin groups, which could extend the shelf-life of salmon fillets from<6 days to 10 days. In the alteration of physicochemical indicators, PDT and natural extracts were able to maintain the pH value and retard lipid oxidation in salmon fillets, while apparently slowing the accumulation (p < 0.05) of total volatile basic nitrogen and biogenic amines, especially the allergen histamine, which contrary to with the variation trend of spoilage microbiota. In parallel, PDT worked effectively (p < 0.05) on the breakdown of adenosine triphosphate and adenosine diphosphate to maintain salmon fillet freshness. Additionally, the physical indicators of texture profile and color did not have obvious changes (p < 0.05) after treated by PDT during the shelf life. Besides, the sensory scores of salmon samples were also significantly improved. In general, PDT not only has a positive effect on organoleptic indicators but is also a potential antimicrobial strategy for improving the quality of salmon sashimi.

Silk fibroin-based colorimetric microneedle patch for rapid detection of spoilage in packaged salmon samples

Spoiled salmon can cause foodborne diseases and severely affects human health. Herein, we report a pH-responsive colorimetric microneedle (MN) patch fabricated from bromothymol blue (BTB) and silk fibroin meth acryloyl (SilMA) (BTB/SilMA@MN patch) for sensing salmon spoilage. The needle tips of MN could penetrate food cling film and insert into fish to extract tissue fluids directly and transport the extracted fluids to the backing layer for color displaying. The color change of BTB/SilMA@MN patches depended on the pH variation resulting from the increase of total volatile basic nitrogen in salmon during storage. The color of MN patches changed from yellow to yellowish green and to final green, indicating salmon changed from fresh to medium fresh and then to putrefied, respectively. Salmon spoilage can be rapidly determined via naked eye recognition and also analyzed on a smartphone in a nondestructive way, allowing consumers to estimate food quality easily and reliably.

Molecular characterization of adenosine monophosphate deaminase 1 and its regulatory mechanism for inosine monophosphate formation in triploid crucian carp

Inosine monophosphate (IMP) is the main flavoring substance in aquatic animal, and adenosine monophosphate deaminase1 (AMPD1) gene is a key gene in IMP formation. At present, the research on the mechanism of AMPD1 regulating IMP formation in aquatic animal is still blank. In this study, in order to study the mechanism of AMPD1 regulating IMP formation in fish, the full open reading frame (ORF) of AMPD1 which was 2160bp was obtained for the first time in triploid crucian carp (Carassius auratus). It encoded 719 amino acids with a molecular mass of 82.97 kDa, and the theoretical isoelectric point value was 6.31. The homology analysis showed that the homology of triploid crucian carp and diploid Carassius auratus was the highest, up to 99%. And the phylogenetic tree showed that triploid crucian carp was grouped with diploid Carassius auratus, Culter alburnus, and Danio rerio. And real-time fluorescence quantitative results showed that AMPD1 was expressed specifically in muscle of triploid crucian carp (p < 0.05). The results of detection the localization of AMPD1 in cells indicated that the AMPD1 was mainly localized in cytoplasm and cell membrane. Further, we examined the effects of glutamate which was the promotor of IMP formation on the expression of AMPD1 and the formation of IMP in vivo and in vitro experiments, the results showed that 3% glutamate and 2 mg/ml glutamate could significantly promote AMPD1 expression and IMP formation in triploid crucian carp muscle tissue and muscle cells (p < 0.05). Then we inhibited the expression of AMPD1 in vivo and in vitro experiments, we found the formation of IMP in muscle tissue and muscle cells of triploid crucian carp all were inhibited and they affected the gene expression of AMPK-mTOR signaling pathway. The all results showed that AMPD1 mediated glutamate through AMPK-mTOR signaling pathway to regulate the formation of fish IMP.

Preparation of yolk-shell structure NH2-MIL-125 magnetic nanoparticles for the selective extraction of nucleotides

Yolk-shell structure magnetic metal-organic framework nanoparticles were prepared via post solvothermal method and employed as a magnetic solid-phase extraction adsorbent for selective pre-concentration of 5'-ribonucleotides by π stacking interaction, hydrogen bonding, and the strong interaction between titanium ions (Ti⁴⁺) and phosphate group. The properties of the materials were confirmed by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectrometry, vibrating sample magnetometer, infrared spectroscopy, thermogravimetric analysis, and Brunauer-Emmett-Teller analysis. The main parameters affecting the adsorption-desorption process, including adsorbent amount, incubation time, incubation temperature, sample pH, shaking speed, elution solution, and elution time, were systematically optimized. Finally, 1.0 mg of adsorbent mixed with 1.0 mL sample solution (10.0 mmol⋅L^-1 NaCl, pH 3.0) and shaken at 135 rpm for 5 min at 40 °C, washed with 1.0 mL Na₃PO₄-NH₃∙H₂O under vortex for 5 min were selected as optimized adsorption-desorption conditions. The binding performance of adsorbent towards five nucleotides was evaluated by static adsorption experiments. The data are well-fitted to the Langmuir isotherm model and the maximum adsorption capacity is 27.8 mg g^-1 for adenosine 5'-monophosphate. The limit of detection of the method is 19.44-38.41 ng mL^-1. Under the optimal conditions, the adsorbent was successfully applied to magnetic solid-phase extraction and high performance liquid chromatography determination of five nucleotides in octopus, chicken, fish, and pork samples.

UPLC/MS-based untargeted metabolomics reveals the changes in muscle metabolism of electron beam irradiated Solenocera melantho during refrigerated storage

Shrimp meat is an extremely perishable product; however, refrigeration can slow down spoilage. In this study, we used electron beam irradiation (EBI) to pre-treat shrimp meat and analyzed the metabolites of the treated shrimp meat during refrigerated storage using metabonomic analysis methods. In total, 4865 metabolites were identified, of which, 103 differential metabolites had KEGG (Kyoto Encyclopedia of Genes and Genomes) IDs. Further, two potential biomarkers were obtained. Based on the results, l-lysine was downregulated, while 2'-deoxyguanosine 5'-monophosphate and dihydroxyacetone phosphate acyl ester were upregulated during the refrigerated storage. The metabolic activity began to weaken gradually after 9 days. However, the different metabolites related to EBI were not identified herein. Nonetheless, the study findings revealed the metabolic changes in Solenocera melantho at the molecular level during refrigerated storage after EBI.