内容: Frozen storage is a prevalent technique for maintaining the freshness of fish. However, fish quality is susceptible to decline throughout the freezing period, substantially impacting its flavor and nutritive content. Hence, this article examines the mechanisms behind the quality degradation and the control strategies employed to preserve fish during frozen storage. Firstly, the formation of ice crystals and the reasons for the decline of fish meat quality were clarified. Secondly, the factors that may lead to quality deterioration during frozen storage were analyzed, including protein denaturation, fat oxidation and enzymatic reaction. Furthermore, the novel freezing control technologies for the deterioration of fish frozen storage quality were reviewed, including the technology of adjusting the nucleation, growth behavior, and recrystallization of ice crystals, and the technology of improving the freezing rate. Finally, the development direction of the research on the deterioration of frozen fish quality in the future was prospected, and novel technologies and methods to improve the quality of frozen fish were pointed out, which is expected to lay a foundation for higher quality frozen fish meat in the future.

内容: Fatty acids are distinctive components of royal jelly (RJ), serving as a crucial indicator for assessing the quality of RJ. This study aimed to establish a rapid and simultaneous quantification method for various fatty acids in RJ utilizing gas chromatography. An optimized two-step extraction process, incorporating ethanol and diethyl ether followed by derivatization with N,O-bis-(trimethylsilyl) trifluoroacetamide, was developed to enhance sensitivity and precision in detecting fatty acids. Validation of the methodology revealed excellent linearity (R2 > 0.999), precision (relative standard deviation (RSD) < 1%), repeatability (RSD < 1%), and recoveries (94.4%–104%). Furthermore, the limits of detection and quantification were found to be low. The results indicated that the method offered reliable and consistent quantification of major fatty acids, thereby improving quality control for RJ and facilitating its applications in food, pharmaceutical, and biochemical research.

内容: This study investigated the flavor quality differences between the edible parts from green and white carapace strains of adult Eriocheir sinensis. The comparison of odor and taste of edible parts, including muscles, ovaries, and hepatopancreas, was conducted through sensory evaluation and quantitative analysis of flavor compounds. The results indicated that the contents of glutamic acid ((0.56 ± 0.03) mg/g vs. (0.43 ± 0.01) mg/g) (P < 0.01), 5ʹ-inosine monophosphate ((17.13 ± 1.36) mg/100 g vs. (12.37 ± 0.29) mg/100 g) (P < 0.05), and equivalent umami concentration ((4.34 ± 0.24) g monosodium glutamate (MSG)/100 g vs. (3.34 ± 0.09) g MSG/100 g) (P < 0.01) in the muscles of white carapace crabs were significantly higher than those of green carapace crabs, resulting in a stronger umami. In contrast, the ovaries showed opposite results. For the hepatopancreas, total bitter free amino acids ((4.28 ± 0.37) mg/g) and nucleotides (inosine and hypoxanthine) were significantly lower in the white carapace strains than in the green carapace strains crabs (P < 0.05). In addition, the content of characteristic aroma substances is higher in the muscles (2-octanone, 3-phenylpropanal) and ovaries (β-citronellol) of white carapace crabs, as well as in the hepatopancreas ((E,E)-2,4-nonadienal, benzoic acid ethyl ester, β-citronellol) of green carapace crabs. In summary, the white carapace crabs outperform the green carapace crabs in most flavor attributes, suggesting that the white carapace crabs have great promotional potentiality. The research results provide a theoretical basis for the evaluation of germplasm resources and further breeding of white carapace strains of E. sinensis.

内容: In this study, the effects of high-intensity ultrasound (HIU, frequency 20 kHz, amplitude 60%, power 450 W) for 0, 6, and 9 min on the emulsifying properties of chicken myofibrillar protein (MP) under different NaCl concentrations (0.2, 0.3, 0.4, and 0.5 mol/L) were investigated. The results showed that the increasing NaCl concentration and prolonged HIU treatment time significantly enhanced the emulsifying activity, the emulsifying stability and storage stability of MP emulsion were increased significantly (P < 0.05), and the particle size of MP emulsion were decreased significantly (P < 0.05). HIU pretreatment decreased the interfacial tension, and increased the apparent viscosity and the absolute zeta-potential of reduced-NaCl MP emulsions. Compared with the non-HIU group at 0.5 mol/L NaCl, the emulsions stability was significantly improved when the HIU time was extended to 9 min under 0.3 mol/L NaCl (P < 0.05). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis result of interfacial MP showed that the band strength of myosin heavy chain and actin significantly increased after 9 min-HIU treatment at both 0.3 and 0.5 mol/L NaCl. Circular dichroism analysis showed that the random coil relative content of interfacial MP was decreased significantly (P < 0.05), and the relative content of α-helix and β-sheet were increased (P < 0.05) after HIU. Extended HIU time could partially alternative the effect of NaCl on the emulsification properties of MP, and improve the stability of the interfacial protein structure and MP emulsion in reduced-salt conditions, which facilitated the processing of lower salt emulsion-based meat products.

内容: The preservation effect of modified atmosphere packaging (MAP) on seafood has been applied widely, but packaging with high concentrations of CO2 will have adverse effects on seafood. This study aimed to elucidate the potential mechanism of the adverse effects caused by MAP with high CO2 concentration at 4 °C. The changes in the quality of salmon fillets under high concentrations of CO2 packaging were demonstrated in this article through indicators such as total volatile basic nitrogen content, microbial counts, thiobarbituric acid reactive substances (TBARS) value, and drip loss. The underlying mechanisms were further explained from the perspectives of protein degradation and endogenous enzymes. The study indicated that the microbial counts in the 90% CO2/10% O2 group were higher than both the 75% CO2/10% O2/15% N2 and 60% CO2/10% O2/30% N2 groups on the 12th day, and there was also an increase in TBARS value and drip loss. On the 2nd day, the caspase-3 relative activity in the 90% CO2/10% O2 group (119.96%) was found to be higher than the 75% CO2/10% O2/15% N2 group (111.99%). On the 12th day, the relative activities of caspase-3 in the 90% CO2/10% O2 group and the 75% CO2/10% O2/15% N2 group were 34.13% and 25.77%, respectively, the latter exhibited the lowest cathepsin activity and the minimum myofibril fragmentation index. The results of free amino acids analysis indicated that the 90% CO2/10% O2 group was also accompanied by an accumulation of more bitter amino acids during storage. The MAP with 75% CO2 had better effect on inhibiting caspases and cathepsins, which could be the main reason to a better muscle quality of salmon fillets at 4 °C.

内容: The effects of salted duck egg white powder (SDEWP) and κ-carrageenan (KC) on autolysis and the properties of modori gel from threadfin bream surimi were investigated. The trichloroacetic acid-soluble peptide content (TCA-SPC) of surimi paste incubated at 65 °C for 60 min decreased significantly (P < 0.05) with the addition of more SDEWP. The decrease in TCA-SPC became lower in the samples incorporated with KC in a dose-dependent manner. Pastes containing SDEWP showed a more retained band of proteins with molecular weight of 45 kDa, while no change in protein pattern was observed when KC was added. The addition of SDEWP significantly improved the gel strength, water-holding capacity, and whiteness of the modori gel in a dose-dependent fashion. The more pronounced improvements in these parameters were observed when SDEWP was added in combination with 0.5 g/100 g KC. Modori gel showed significantly improved texture profiles when added with both SDEWP and KC. A denser and finer gel microstructure in modori gel was attained when added with both SDEWP and KC. Thus, SDEWP effectively prevented autolysis in surimi, while a combination of SDEWP and KC improved the gel properties of modori gel, in which maximal degradation of gel was induced by endogenous proteases.

内容: This study introduced an electrochemical sensor for the rapid, sensitive, and accurate detection of ciprofloxacin (CIP). The sensor utilized a screen-printed carbon electrode (SPCE) modified with Pd@Nb2C nanocomposites, which were prepared through the in-situ reduction of palladium nitrate on Nb2C nanosheets, resulting in a uniform distribution of Pd nanoparticles. Subsequently, they were drop-coated onto the SPCE surface, forming a Pd@Nb2C/SPCE electrochemical sensing platform. The electrochemical analysis demonstrated the excellent electrochemical performance of the sensor. Pd@Nb2C/SPCE showed a consistent linear correlation between redox peak current (IP) and CIP concentration (cCIP) in the range of 10–150 μmol/L, boasting a detection limit of 3 μmol/L. Notably, this technique tracked CIP in both whole and skimmed milk, achieving a high recoveries of 96.36%–105.40% (n = 3). Moreover, the sensor exhibited exceptional selectivity towards CIP, remaining unaffected by various interferences such as sulphonamide, amoxicillin, tetracycline, and chloramphenicol. These findings hold enormous promise for enabling real-time and rapid monitoring of CIP in milk.

内容: The quality differences and Raman spectroscopic features of beef, which was frozen for 0–11 months followed by being thawed and displayed for 0–21 days were investigated. Frozen storage did not significantly affect the color blooming ability, in which minimal change in the color parameter redness and yellowness values of thawed beef in the later stage of frozen storage occurred. As such, it was not able to distinguish between frozen-thawed and non-frozen-thawed meat directly in terms of color changes. The total viable count and the total volatile basic nitrogen content increased sharply in the frozen-thawed meat subjected to 11-month frozen storage. The thiobarbituric acid reactive substances value increased dramatically from 0.18 to 0.29 mg/kg during 11-month frozen storage. Raman spectroscopy data showed that the stability of the protein secondary structure of thawed beef became worse after 3 months of frozen storage, of which the relative content of α-helix and β-sheet decreased significantly to 21.46% and 28.94% during 11-month frozen storage, respectively. The findings suggest that quality deterioration occurred for the frozen-thawed beef, and Raman spectroscopy could be a potential method to distinguish unfrozen meat from frozen-thawed meat.

内容: The aim of this experiment was to investigate the effect of a natural additive Rosa roxburghii Tratt. extraction (RRTE) on the gel properties and flavour of hairtail (Trichiurus lepturus) surimi gels. The effects of different additive concentrations of RRTE on the flavour improvement of hairtail surimi gels were systematically investigated by combining the electronic nose and sensory evaluation techniques. The results showed that the addition of RRTE, especially 2% (m/m) RRTE, could effectively improve the odour score; enhanced the gel strength, water-holding capacity and rheological properties; improved the elasticity, hardness and viscoelasticity of the hairtail surimi gels. The results of water migration and protein secondary structure analysis showed that RRTE could effectively stabilise the internal water distribution of hairtail surimi gels and inhibit protein denaturation. Microstructural observation showed that the gel structure of hairtail surimi in the RRTE added group was more uniform and dense, and the fractal dimension was reduced. The comprehensive results showed that RRTE, as a natural additive, could significantly improve the gel properties and flavour of hairtail surimi gels, providing a scientific basis for the high value-added processing of hairtail surimi products.

内容: In this study, the changes in flavor characteristics of dried pork slice at various stages of air fryer processing were systematically traced and analyzed using E-nose, gas chromatography-ion mobility spectrometry (GC-IMS) and lipidomics. The results showed that the volatile organic compounds (VOCs) and lipid composition of dried pork slice changed significantly at different processing stages. The analysis showed that the E-nose was able to differentiate between the odor profiles of different processing stages of dried pork slice, with significant differences between the samples. The GC-IMS detected 74 VOCs during the processing of dried pork slice, of which 61 were characterized and 19 differential signature VOCs were screened based on the partial least squares discriminant analysis (PLS-DA) model. Aldehydes and pyrazines increased significantly as the processing stage progressed, especially in the finished product stage. A total of 780 lipids were detected by lipidomics, among which triglycerides and phosphatidylcholine accounted for 50.26% and 35.00%, respectively, as well as degraded significantly during processing, and 38 differential lipid compounds were screened by using the PLS-DA model. Correlation analysis revealed that ethyl 2-hydroxypropanoate-D, ethyl 2-hydroxypropanoate-M, and 1-butanol,3-methyl-,acetate-D showed negative correlation with 38 differential lipids, while positive and negative correlations were found between the remaining 16 major VOCs and the differential lipids, indicating that lipid degradation was closely related to the generation of flavor compounds. This study revealed the key data of lipid degradation and flavor generation, which provided a scientific basis for optimizing the air fryer processing and enhancing the flavor quality of dried pork slice.