ATP-related Compounds Research Articles

Postharvest quality evaluation of masu salmon (Oncorhynchus masou) during ice storage by spinal cord and bleeding

The study investigated the impact of spinal cord-treated and bleeding processes on the quality changes of postharvest aquaculture masu salmon during ice storage. Fish underwent ice storage for 0–70 h, and the rigor mortis, ATP-related compounds, K-value, free amino acids, drip loss, and pH were monitored. Spinal cord-treated and bleeding fish started rigor mortis at 1.5 h, reaching full at 4.5 h, and persisted for 21 h, while control samples exhibited an earlier onset of rigor mortis at 0.5 h, reaching a maximum of 1 h. The ATP content showed a significant difference during the initial storage period from 0 to 3 h, with spinal cord-treated and bleeding fish showing a higher ATP content and lower K-value, and followed a similar trend, reaching around 20–23 % after 70 h of storage. The most abundant free amino acid detected was Ans, which occupied over 70 %, with others including Tau, Gln, Thr, Ser, Gly, Ala, His, and Glu. Spinal cord-treated and bleeding fish exhibited higher contents of Thr, Ser, and Gly, contributing to sweetness (p < 0.05). The umami flavor compound Glu increased with storage time, particularly in the spinal cord and bleeding fish, while IMP was most abundant during the mid-storage period, with higher levels in the spinal group with the prolong of storage time. HxR and Hx primarily contributed to bitterness, increasing with storage time, whereas His did not show a significant increase in the later storage period. Spinal cord and bleeding treatment demonstrated reduced drip loss (p < 0.05). The pH value fluctuated between 6.2 and 6.5 with no significant differences between the two treatments. The spinal cord-treated and bleeding treatments minimized stress and resulted in overall better postharvest quality, aligning with fish welfare.

Insight into flavor changes in bighead carp (Aristichthys nobilis) fillets during storage based on enzymatic, microbial, and metabolism analysis

The flavor alterations in bighead carp subjected to varying storage temperatures and the underlying metabolic mechanism were elucidated. Analysis of volatile flavor compounds, electronic nose, free amino acids, ATP-related compounds, and sensory evaluations uncovered a progressive flavor deterioration during storage, especially at 25 °C. Metabolomics-based flavor relating component profiling analysis showed that free fatty acids formed various fatty aldehydes including (E, E)-2,4-heptadienal and nonanal under lipoxygenase catalysis. Alcohol dehydrogenase and alcohol acyltransferases were intimately involved in alcohol and ester generation, while alkaline phosphatase, 5′-nucleotidase, and acid phosphatase were closely associated with IMP, Hx, and HxR conversion, respectively. Aeromonas, Serratia, Lactococcus, Pseudomonas, and Peptostreptococcus notably influenced flavor metabolism and enzyme activities. The metabolism disparities of valine, leucine, isoleucine, lysine, and α-linolenic acid could be the primary factors contributing to flavor metabolism distinctions. This study offers novel insights into the flavor change mechanisms and potential regulation strategies of bighead carp during storage.

Specific spoilage bacteria in cold chain logistics: A study on ATP-related compounds degradation in large yellow croaker (Larimichthys crocea)

This study evaluated the contribution of three spoilage bacteria (Shewanella putrefaciens (S. putrefaciens), Pseudomonas fluorescens (P. fluorescens), and Aeromonas salmonicida (A. salmonicida)) to the degradation of adenosine triphosphate (ATP)-related compounds in fish juice and fillet systems of large yellow croaker during cold chain logistics. The contribution of spoilage bacteria was explored by determining the microbial counts, ATP-related compounds, and associated enzyme activities. The results revealed that the S. putrefaciens, P. fluorescens, and A. salmonicida have the highest activities in 5′-nucleotidase (5′-NT), acid phosphatase (ACP), and alkaline phosphatase (AKP), with 49.78, 162.24, and 142.3 U/gprot, respectively. The rapid degradation of inosine monophosphate (IMP) occurs with increasing 5′-NT activity. It indicates that S. putrefaciens, P. fluorescens, and A. salmonicida mainly secreted 5′-NT, ACP, and AKP to degrade IMP, respectively, and that 5′-NT was the key enzyme in degrading IMP. All three are notable producers of purine nucleoside phosphorylase (PNP) and xanthine oxidase (XOD). The results showed that S. putrefaciens is the primary bacterium in the pre-degradation phase of ATP-related compounds, and A. salmonicida presumably dominates in the post-degradation phase. This study offers critical insights into the research on spoilage mechanisms of marine fish throughout the cold chain logistics.

Effects of slightly acidic electrolyzed water and ginger (Zingiber officinale Roscoe) juice on the quality and myofibrillar protein structure of silver carp (Hypophthalmichthys molitrix) fillets during cold storage

This study aimed to investigate the effects of slightly acidic electrolyzed water (SAEW) pretreatment combined with ginger (Zingiber officinale Roscoe) juice (GJ) on the quality, sensory characteristics, and myofibrillar protein structure of silver carp (Hypophthalmichthys molitrix). The results revealed that the SAEW-GJ delayed microbial spoilage by reducing the total viable counts and Pseudomonas spp. Moreover, the freshness of silver carp fillets was maintained by maintaining lower total volatile base nitrogen (TVB-N), ATP-related compounds, and free amino acids (FAAs). SAEW-GJ delayed myofibrillar protein oxidations by inhibiting the generation of carbonyl groups and maintaining a higher Ca2+-ATPase activity and sulfhydryl content. We also observed that SAEW-GJ treatment maintained myofibrillar organized secondary structure by keeping higher α-helix content and stabilized tertiary structure during cold storage. These results suggested that the SAEW-GJ could be used to enhance the quality of silver carp and prolong the shelf life by at least 6 days during cold storage.

Effect of Specific Spoilage Organisms on the Degradation of ATP-Related Compounds in Vacuum-Packed Refrigerated Large Yellow Croaker (Larimichthys crocea).

This study examined the spoilage potential of specific spoilage organisms on the degradation of adenosine triphosphate (ATP)-related compounds in vacuum-packed refrigerated large yellow croaker. The total viable count (TVC), ATP-related compounds and related enzymes of vacuum-packed refrigerated large yellow croaker inoculated with different bacteria (Pseudomonas fluorescens and Shewanella putrefaciens) were characterized using the spread plate method, high-performance liquid chromatography and assay kits, respectively. Results indicated that the TVC for both control and Shewanella putrefaciens groups reached spoilage levels at days 9 and 15, respectively. The changes of adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP) and adenosine deaminase activity across all groups showed no significant difference attributable to microbial growth. The results suggested that ATP to inosine monophosphate (IMP) degradation primarily occurs via fish's endogenous enzymes, with minimal microbial involvement. On day 12, the IMP content in fillets inoculated with Pseudomonas fluorescens (0.93 μmol/g) was half higher than in those inoculated with Shewanella putrefaciens (0.57 μmol/g). Both spoilage organisms facilitated IMP degradation, with Shewanella putrefaciens making a more substantial contribution. Analysis of K values and correlation coefficients revealed that Shewanella putrefaciens was the primary factor in the freshness loss of refrigerated vacuum-packed large yellow croaker. These findings offer a reference for understanding quality changes in refrigerated large yellow croaker, especially regarding umami degradation at the microbial level.

Microbial Composition and Quality Changes in Whole Golden Pomfret (Trachinotus ovatus) During Refrigerated, Ice, and Vacuum-Packed Storage

ABSTRACT This study evaluated the quality and bacterial composition changes in whole golden pomfret under refrigeration, ice storage, and vacuum packaging at 4°C . Ice storage and vacuum packaging delayed sensory quality deterioration, limited spoilage bacteria proliferation, and slowed biogenic amines formation, total volatile base nitrogen accumlation, and ATP-related compounds degradation. In addition, Bacillus dominated fresh golden pomfret. Psychrobacter, Shewanella, and Acinetobacter were predominant in control and ice storage groups, while Shewanella and Aeromonas prevailed in the vacuum packaging group after storage. In conclusion, the best storage condition for whole golden pomfret fish is ice storage.

Real-time and non-destructive control of the freshness and viability of live mussels through portable near-infrared spectroscopy

This study introduces the application of a novel, rapid, and non-destructive method employing portable near-infrared (NIR) spectroscopy to assess the freshness and viability of live mussels throughout their shelf-life. NIR spectra ranging from 908 to 1676 nm were collected from 150 Mediterranean mussels (Mytilus galloprovincialis, L.) over a 10-day storage period. Simultaneously, measurements of weight loss, intravalvular liquid pH, and nonprotein nitrogen levels were taken. A predictive model was established by correlating the multivariate information derived from NIR spectral data with days of storage under refrigerated conditions using orthogonal partial least squares regression (OPLSR) analysis. While physical and chemical parameters (except for gradual weight loss due to water leakage) showed no distinct trends throughout storage, the fourth derivative-preprocessed NIR spectra enabled the construction of an OPLSR model that, following cross-validation, exhibited a correlation coefficient of 0.86 and, following external validation with new mussel samples, an average accuracy (root mean square error of prediction) of just 1.3 days. The predictive power of the model was primarily attributed to specific NIR wavelengths associated with key chemical features, including unsaturated fatty acids, nitrogen compounds, water content, glycerol, and ATP-related compounds that, collectively, constituted a distinctive fingerprint for forecasting mussel storage duration. The performance of the tool, along with its environmentally friendly, non-invasive, real-time, and cost-effective characteristics, align with industry control procedures and inspection needs, allowing effective freshness and viability assessment of live mussels across the food supply chain.

Fatty acid and energy (ATP-related compounds) metabolism of Eurasian perch (Perca fluviatilis) sperm: Endogenous metabolic strategy

Structural (fatty acids) and energetic (ATP-related compounds) processes of spermatozoa of Eurasian perch (Perca fluviatilis) has been studied. Present study identified changes in fatty acids and adenosine phosphate stoichiometries as sperm ascended from basal metabolism (pre-activation quiescent state) to active metabolism (post-activation exhaustion). Results suggest long chain unsaturated (C14:0, C16:0) and monounsaturated fatty acids (C16:1) were significantly utilized (p < 0.05) for energy yielding purposes. Polyunsaturated fatty acids, C20:5n-3 (EPA) content was reduced from basal metabolism (1.09–2.57 mg g−1) to post-activation (0.69–2.39 mg g−1), while C20:4n-6 (ARA) and C22:6n-3 (DHA) remained preferentially conserved. In a way that ARA: EPA and DHA: EPA ratios became significantly higher (p < 0.05) in exhausted than quiescent state, for potential maintenance of membrane fluidity by DHA or eicosanoid activity (anti-inflammatory EPA to pro-inflammatory ARA balancing) during motility. Although endogenous fatty acid bioconversion capabilities could not be proved by the present study, these findings encourage future research. In terms of nucleotides, K-value (relative degradation of ATP; metabolic loss) was 30% at basal metabolism. ATP consumption equalled production at quiescent state, as the ratio of forward and backward reaction products in adenylate kinase reaction was maintained at ≈1 (equilibrium). With activation, 0.21–0.65 nmol ATP second−1 per 109 spermatozoa was metabolized and K-value showed 85–90% of pre-stored ATP pool degraded to non-calorific inosine and hypoxanthine. There was missing AMP, lowered ATP: ADP ratio and adenylate kinase reaction equilibrium was lost. We conclude a potential mismatch between glycolysis and substrates led to exhaustion in P. fluviatilis sperm, despite a tendency towards selective FA utilization to ensure membrane fluidity (DHA conservation) or prostaglandin and anti-inflammatory responses (ARA and EPA) till its last moments.

Characterization and discrimination of the flavor profiles of Chinese indigenous sheep breeds via electronic sensory, smart instruments and chemometrics

This study was conducted to analyze the flavor profile of six commercially available Chinese indigenous breeds of sheep meat and to distinguish them based on their flavor characteristics. Various techniques such as gas chromatography-mass spectrometry (GC-MS), electronic nose (E-nose), high performance liquid chromatography (HPLC) and electronic tongue (E-tongue) were employed to analyze both volatile and non-volatile compounds in the meat samples. The results showed that, a total of 28 volatile compounds in sheep meat were detected, with 1-octen-3-ol, 1-pentanol, hexanal, octanal, and nonanal identified as the major contributors to its aroma. Tan Sheep and Oula Sheep had significantly higher concentrations of 1-pentanol, nonanal, 1-octen-3-ol, 1-octanol, and hexanoic acid than other breeds. Sweet amino acids were the most abundant free amino acids, comprising 72–85% of the total FAAs, and inosinic acid was the most abundant ATP-related compound. Small-Tailed Han sheep had significantly higher levels of SFAAs, total FAAs, and AMP, while Tan sheep had significantly higher levels of UFAAs, and Oula Sheep had significantly higher levels of GMP. The response values of differential electronic sensors W5S, W1W, NMS, PKS, and SCS were found to be useful in discriminating between breeds of sheep meat. The fusion electronic sensory signals were used to train support vector machine and random forest models, both achieving 100% accuracy in discriminating between sheep breeds.

The potential application of a novel biodegradable film activated with co-encapsulated epsilon-poly-l-lysine and Spirulina platensis extract for fish fillets preservation

In this study, novel biodegradable films were fabricated by adding W2/O/W1 emulsion (containing coencapsulated Spirulina platensis extract (SE, 800 µg/mL) and epsilon-poly-l-lysine (EPL, 200 µg/mL)) into soybean polysaccharide (SBP)- bovine skin gelatin (GL). Emulsions with ζ-potential of − 40.33 to − 50.93 mV and droplet size of 6.32–9.69 µm were achieved. The incorporation of microemulsion into the structure of the film was justified by ATR-FTIR and SEM. The water solubility, water vapor permeability, tensile strength and elongation at break of the films loaded with microemulsions were improved. Films containing coencapsulated SE-EPL presented high antioxidant and antibacterial activities. Coating grass carp fillets with the film significantly decreased the K-value and ATP-related compounds (especially hypoxanthine, Hx), limited the formation of 8 biogenic amines (tryptamine, phenylethylamine, putrescine, cadaverine, histamine, tyramine, spermidine, and spermine), protected the sensorial quality, and increased their shelf life by approximately 4 days, proposing its potential application in preserving aquatic products.

Determination of ATP-related compounds by HPLC to study the effect of cell-free supernatants of Lactiplantibacillus plantarum on the shelf life of sliced dry-cured ham

This research aimed to study the evolution of ATP-related compounds in dry-cured ham and to assess their suitability as chemical markers of food contamination. A rapid high-performance liquid chromatography (HPLC) method was developed for the analysis of five ATP-related compounds namely, ATP, ADP, AMP, hypoxanthine, and Ino in sliced dry-cured ham. Moreover, a positive correlation between ATP content and microbial load was found in ham during storage. In addition, the method developed herein was employed to quantify ATP-related compounds in sliced dry-cured ham wrapped in a novel antibacterial packaging film containing the cell-free supernatant (CFS) of a probiotic Lactiplantibacillus plantarum strain. The contents of ATP-related compounds in ham samples wrapped in the antibacterial packaging film were lower than in control samples during the 7 days of storage (181 vs 269 mg/kg on day 2; 247 vs 286 mg/kg on day 5; 272 vs 297 mg/kg on day 7). Thus, the evaluated CFS could be considered in packaging material applications for the preservation of sliced ham. This study presents an effective method to assess the quality of sliced ham, which might also contribute to the adoption of active packaging in the food industry.

Effect of alginate-gallic acid coating on freshness and flavor properties of Mackerel (Scomberomorus commerson) fillets under refrigerated storage

This study investigates the effect of sodium alginate-gallic acid (ALG-GAL) coating on mackerel's flavor compounds and quality properties during cold storage at 4 °C for 12 days. To this end, freshness quality indicators, including biogenic amines (BAs), volatile organic compounds (VOCs), ATP-related compounds, K value, total viable counts (TVC), thiobarbituric acid (TBA), and sensory assessment, were measured. During storage, eight BAs, i.e., histamine (HIS), tyramine (TYR), putrescine (PUT), cadaverine (CAD), 2-phenylethylamine (2-PHE), agimation, spermine (SPM), and spermidine (SPD) were identified in control and treated samples. The biogenic amine index (BAI) for control samples was 56.25 at the time of sensory rejection (day 6). BAI for samples coated with ALG-GAL did not exceed 20 mg/100 g at the time of sensory rejection (day 12). The fillets treated with the ALG alone or incorporated with GAL possessed a different trend in the retardation of VOCs, including aldehydes, ketones, alcohols, and hydrocarbons. Seven key flavors VOCs, including 3-methylbutanal, phenylacetaldehyde, E-2-hexanal, 1-hexanol, 1-octen-3-ol, 2,3 pentanedione, and hydroxyl-2-butanone, were identified in control and coated samples. Samples coated with ALG and GAL were of significantly higher quality (p < 0.05) throughout storage, which could result in lower Inosine (HxR) concentrations and K values. The results of TVC showed that use ALG-GAL had lower bacterial counts compared to control (p < 0.05). The ALG-GAL-coated samples retarded the increase in the contents of TBA during storage. In addition, significant differences in sensory scores between ALG and ALG-GAL were observed (p < 0.05). In this study, aldehydes and hypoxanthine (Hx) were the main compounds in the formation of off-flavor. These results revealed that ALG coating combined with GAL improved the quality of refrigerated mackerel fillets by decreasing off-flavor compounds and TVC population.

Mechanism of freshness-lock during the quality determination period of farmed turbot Scophthalmus maximus revealed by foodomics

A series of biochemical changes occur in the muscles of postmortem fish, resulting in an extremely easy decline in freshness. The early stage of postharvest can be regarded as the quality determination period (QDP) oficeice seafood. The QDP handlings influence the final quality of fish product. Bleeding at ice seawater was conducted to lock the freshness of farmed turbot. The pH, ATP-related compounds and K values were measured. A non-target metabolomics technique was used to elucidate the mechanism of freshness-lock. The results showed that the levels of pH and ATP-related compounds were decreased slowly in the fish of freshness-lock, while K values were lower than those in no freshness-lock fish during cold storage. The metabolomics analysis revealed that 25 metabolites were significantly changed in the muscles of turbot after 2 d of cold storage. After freshness-lock treatment, 6 metabolites reversed in the muscles of turbot, with the rises in glycerol 3-phosphate, dihydroxyacetone phosphate, and decanoyl-l-carnitine and the drops in pyruvaldehyde, D-lyxose, and d-ribose. This study indicates that locking freshness during QDP of fish has a delayed effect on the quality deterioration and can prolonging the shelf-life of fresh product.

Effects of cooling rates during depuration on the quality of Pacific oysters (Crassostrea gigas) at anhydrous preservation stage

The Pacific oyster could be affected by several pressure sources during cold chain logistics, which reduce the quality of oyster, and even improve its mortality. For improving the quality of oyster, the effects of depuration process at different cooling rates (1, 3, 7, 11 and 16 °C/h) on selected Pacific oyster were studied. The results indicated that extreme fluctuations in the depuration temperatures could affect the survival rates and qualities of oysters. The oysters exhibited low survival rates, glycogen contents and pH values at an increased cooling rate. Their contents in the 1 °C/h group after 3 d preservation were 100 %, 16.30 ± 1.64 mg/100 g and 6.72 ± 0.01, respectively, while there were 71 %, 7.72 ± 0.88 mg/100 g and 6.53 ± 0.01 in the 16 °C/h group after 3 d preservation, respectively. Furthermore, the ATP-related compounds were affected by the different cooling rates. AMP and IMP were the main ATP-related compounds, and their contents in the 1 °C/h group after 3 d preservation were 37.21 ± 1.10 mg/100 g and 29.47 ± 1.10 mg/100 g, respectively, while there were 32.07 ± 1.10 mg/100 g and 13.16 ± 1.60 mg/100 g in the 16 °C/h group after 3 d preservation, respectively. The proportions of the total umami, as well as the sweet amino acids also decreased, the proportions of the umami amino acids and sweet amino acids in the total amino acids, were 31.37%–38.80%, and their proportions in 1 °C/h group were higher than that in 16 °C/h group. Conversely, the fatty acid content of each group exhibited significant differences. Combined with the above results, the oyster maintained a high survival rate and higher quality at a cooling rate of 1 °C/h during depuration.

Novel intelligent films containing anthocyanin and phycocyanin for nondestructively tracing fish spoilage

Potential pH-responsive films were developed based on incorporating anthocyanin, phycocyanin, and a mixture of anthocyanin-phycocyanin (at a ratio of 3:1 v/v) within composite gelatin (1.5 g / 100 g film solution)/soybean polysaccharide (2.5 g / 100 g film solution) matrices. FTIR and SEM assessments certified the incorporation of the pigments into the film matrices. All the colorimetric films were highly sensitive when exposed to headspace ammonia, except the phycocyanin-incorporated film. Moreover, the fabricated intelligent films were conducted to trace the spoilage process of grass carp. An obvious relationship between the color (L*, a*, b*, ΔE) of indicators and pH, TVB-N, bacterial growth, ATP-related compounds, and K-value of the fish was observed. The film incorporated with mixed Ipomoea nil extract and phycocyanin possessed the best color variations (dark orange, pink, dark blue) with the degree of fish spoilage. Therefore, this intelligent film can be considered a promising sensor for monitoring fish freshness non-destructively.

Comparison of oxidative stress-mitochondria-mediated tenderization in two different bovine muscles during aging

The aim of this study was to investigate the differences in the effects of mitochondria-involved energy metabolism and caspases activation on postmortem tenderness in different muscle fiber types. Beef Longissimus thoracis (LT) and Psoas major (PM) muscles showed significant difference in mitochondrial function. Our data revealed that PM suffered from higher levels of reactive oxygen species (ROS) earlier than LT, causing faster mitochondrial swelling and rupture. Additionally, faster metabolism of ATP-related compounds and activation of caspase-9 appeared in PM, but the activity of caspase-3 in PM was lower than that in LT. Differences in myofibril fragmentation index (MFI) of LT and PM at different aging stages suggested that energy metabolism and caspases activities may play a role in tenderness at different aging stages. These results indicated that oxidative stress-mitochondria-mediated tenderization process could be muscle-specific.

Effects of Chitosan-Grafted-Phenolic Acid Coating on Quality and Microbiota Composition of Vacuum-Packaged Sea Bass (Lateolabrax japonicus) Fillets during Chilled Storage

The aim of this research was to experimentally assess the effect of chitosan (CS)-grafted phenolic acid (CS-g-PA) derivatives on the quality and microbiota composition of vacuum-packaged sea bass (Lateolabrax japonicus). Samples were treated by deionized water (CK), 1% CS, 1% CS-g-PA copolymer, and 1% CS-grafted gallic acid (CS-g-GA) copolymer for 10 min and combined with vacuum packaging stored at 4°C to analyze the microbiological and physicochemical indicators; they were also combined with 16s RNA high-throughput sequencing to explore the effects of CS derivatives on quality and microbial composition. The results showed that the treatment of CS-g-GA and CS-g-PA could retard the increase of pH, total volatile basic nitrogen, and the K value. The degradation of ATP-related compounds, production of biogenic amines, and growth of spoilage bacteria were inhibited by CS-g-GA and CS-g-PA. Moreover, CS-g-GA and CS-g-PA performed better in the inhibition of lipid oxidation by the analysis of thiobarbituric acid reactive substances and relative fluorescence intensity. According to the results of high-throughput sequencing, the diversity of microbial composition in all groups was decreased significantly during chilled storage, especially in the CK group. The predominant microorganism was Acinetobacter in the middle period of storage, while Pseudomonas and Shewanella became predominant at the end of storage. The treatment of CS-g-GA and CS-g-PA had significant effects inhibiting the growth of Shewanella during storage. On the basis of the analysis of the microorganism and physicochemical quality, compared with the CK group, CS-g-GA and CS-g-PA can maintain the good quality of sea bass fillets and prolong the shelf life for another 12 days.

Unraveling the Effects of Biochemical Drivers on the Bacterial Communities and Volatile Profiles in Refrigerated Sturgeon Filets at 4°C.

Spoilage bacteria seriously influence the flavor and quality of fish meat. In this study, we investigated the quality characteristics, bacterial community, and volatile profiles of refrigerated (4°C) sturgeon filets during 10-day storage. On day 10, the refrigerated samples showed the lowest bacterial diversity and the largest difference in microbiota and biochemistry. The dominant genera in the fresh samples were Macrococcus, Acinetobacter, Moraxella, Brucella, and Pseudomonas, while the dominant bacteria changed into Acinetobacter, Carnobacterium, Macrococcus, Pseudomonas, and Psychrobacter at the end of storage. Our results suggest that these dominant taxa contribute to the spoilage of the refrigerated sturgeon filets. Meanwhile, during the storage, total viable counts, total volatile basic nitrogen, thiobarbituric acid-reactive substances, and trichloroacetic acid-soluble peptide significantly increased (P < 0.05), while the sensory score decreased steadily. Additionally, the ATP-related compounds and the K-value showed similarly increasing trends. The shelf-life of the refrigerated sturgeon filets was less than 8 days. The gas chromatography–ion mobility spectrometry results suggest that hexanal, ethyl acetate, ethanol, butanal, 1-propanol, isopentyl alcohol, 2-pentanone, 2-heptanone, ethyl propanoate, and propyl sulfide are potential chemical spoilage markers. The predicted metabolic pathways indicated an abundant carbohydrate metabolism and amino metabolism in the refrigerated sturgeon filets. This study provides insight into the determinants of sturgeon shelf-life and the spoilage process involved in refrigerated fish.

Effects of slightly acidic electrolyzed water pretreatment combined with compound bio‐preservatives on quality and microbiota changes of refrigerated obscure pufferfish ( Takifugu obscurus )

The evaluation of ε-polylysine hydrochloride (PLH) and rosemary extract (RE) combined with slightly acidic electrolyzed water (SAEW) on the quality and microbiota changes of obscure pufferfish (Takifugu obscurus) was studied during refrigerated storage at 4 ± 1°C. The fish samples were first impregnated with SAEW and then dissolved in sterile water (CK) and different solutions (0.2% RE, 0.3% PLH, 0.2% RE+0.3% PLH (RP)). Changes in microbiological indicators (total viable counts [TVC], psychrophilic bacteria counts [PBC], pseudomonas bacteria counts, H2S-producing bacteria counts) and physiochemical indexes (ATP-related compounds, K value, total volatile basic nitrogen [TVB-N], and biogenic amines content) were also examined, the microbial composition of the samples was analyzed using high-throughput sequencing. Results showed that PLH treatment had the lower microbial counts and TVB-N. The degradation of inosine monophosphate (IMP), the production of hypoxanthine riboside (HxR) and hypoxanthine (Hx) in treated groups were slower than that of CK group. Moreover, RP group effectively delayed the production of biogenic amines. Illumina-MiSeq high throughput sequencing results demonstrated that the microbiota of each group became less diverse during storage, and Janthinobacterium in treated groups increased significantly. Pseudomonas became the major predominant microbiota of obscure pufferfish (Takifugu obscurus) at the end of storage. According to the results of TVC, SAEW combined with RP could prolong the shelf-life of obscure pufferfish for another 6 days. Practical applications Obscure pufferfish (Takifugu obscurus) is enthusiastically welcome due to the palatability and nutritional value of its flesh. However, it is vulnerable to spoilage caused by microbial growth and metabolisms. Based on the results of microbiological analysis total viable counts, compared with CK group, samples with compound bio-preservatives treatment maintained good quality and prolonged the shelf life of obscure pufferfish for another 6 days.

Mitochondrial activity as an indicator of scallop (Mizuhopecten yessoensis) adductor muscle in early cold storage.

The purpose of this study was to reveal the role of mitochondria in indicating a change in the freshness of the adductor muscle of Mizuhopecten yessoensis during cold storage and hardening. The adductor muscle hardens after 96h of cold storage and reaches the maximum degree of hardening in 6h. In this study, after hardening (102 h), the muscle fiber structure obviously broke and curled, and the sarcomere structure disappeared at 150 h. After hardening (102 h), the morphology of the mitochondria changed, including swelling, cristea breaking and membrane structure disappearance. The arginine phosphate content decreased gradually from the initial 4.618 to 1.306µmol/g at 48 h, and there was no further obvious change. The ATP content decreased from 6.02 to 1.07µmol/g in 120 h. The mitochondrial membrane potential (Δφ) was measured by a fluorescence method (JC-1). The changes in freshness could be divided into three classes according to the Δφ difference between the mitochondria in the adductor muscle after adding ADP and CCCP. Mitochondrial function was complete from 0 to 6 h; mitochondrial function began to decline at 6 to 48 h; and mitochondrial function completely disappeared after 48 h. The results showed that the mitochondrial membrane potential compared with other indicators could more sensitively reflect the changes in freshness during the cold storage hardening process of the adductor muscle. PRACTICAL APPLICATION: It is very important to interprete the post-mortem energy metabolism for controlling the muscle quality of Yesso scallop. The K value which was developed based on ATP-related compounds is widely used in evaluating the freshness of seafood. Mitochondria is the main sites of cellular energy metabolism and the changes of its structure and activity can sensitively reflect the quality changes in muscle cell. It is expected to develop a more sensitive freshness evaluation index.