Sensory, physicochemical, and microbiological changes in vacuum packed channel catfish (Clarias lazera) patties during controlled freezing-point storage

Integrated Metabolomic and Microbial Analysis of Quality Dynamics in Channel Catfish (Ictalurus punctatus) Under Refrigerated and Frozen Storage

Channel catfish (Ictalurus punctatus) is a widely consumed freshwater fish known for its nutritional value but is highly prone to spoilage. This study investigated the quality changes of catfish muscle tissue under refrigeration and freezing through physicochemical, metabolomic, and microbial analyses. Results revealed that sensory scores decreased significantly during storage, with frozen samples maintaining similar scores to refrigerated ones after extended periods. Protein degradation and lipid oxidation, indicated by TVB-N and TBARS levels, were more pronounced during prolonged freezing. Metabolomic profiling identified 261 differential metabolites under long-term freezing, including elevated phosphatidylcholines, sphingomyelins, and disrupted amino acid pathways. Shifts in spoilage-associated microbial genera, such as Pseudomonas, and the correlations between microbial genera and specific metabolites, such as Methylobacterium with methylmalonic acid, highlighted microbial-driven spoilage processes. These findings provided a comprehensive understanding of quality deterioration during storage, guiding the development of enhanced preservation strategies for aquatic products.

Changes in water holding capacity of chilled fresh pork in controlled freezing-point storage assisted by different modes of electrostatic field action

Electrostatic field-assisted low-temperature preservation is considered a novel technology, which provides an effective means of extending the shelf-life of meat. This study aimed to investigate the effects of different output time modes of a high voltage electrostatic field (HVEF) on the water holding capacity (WHC) of chilled fresh pork during controlled freezing-point storage. Under a direct current HVEF generator, chilled fresh pork samples were treated by the single, interval, or continuous HVEF treatment, with a control check group receiving no HVEF treatment. It was determined that the WHC of the continuous HVEF treatment higher than the control check group. This difference was proven by analyzing the moisture content, storage loss, centrifugal loss, cooking loss, and nuclear magnetic resonance imaging. Furthermore, the mechanism behind HVEF-assisted controlled freezing-point storage reduced the moisture loss was conducted by examining the changes in the hydration characteristics of myofibrillar protein. The study revealed that myofibrillar proteins exhibit high solubility and low surface hydrophobicity under continuous HVEF. Additionally, continuous HVEF has been demonstrated to effectively maintain the higher WHC and lower hardness of myofibrillar protein gel by inhibiting the water molecule migration. The demonstration of these results showcases the effectiveness of electrostatic fields for the future physical preservation of meat.

A comprehensive insight into the effects of microbial spoilage, myoglobin autoxidation, lipid oxidation, and protein oxidation on the discoloration of rabbit meat during retail display

The effects of the retail display temperature (8 °C, 3 °C and - 1 °C) on the discoloration of the Longissimus thoracis et lumborum of rabbits and the associations among such effects with microbial spoilage, myoglobin autoxidation, lipid oxidation, and protein oxidation were investigated. The total aerobic count, total volatile basic nitrogen content, metmyoglobin content, protein carbonyl content, and contents of thiobarbituric acid-reactive substances steadily increased during retail display. Moreover, the lightness and redness of the rabbit meat significantly (P < 0.05) declined over time, whereas the yellowness increased considerably (P < 0.05) with prolonged retail time. Canonical correlation analysis suggested that microbial spoilage, myoglobin autoxidation, lipid oxidation, and protein oxidation jointly affected rabbit meat color. Linear mixed models further revealed that microbial spoilage, myoglobin autoxidation, lipid oxidation and protein oxidation positively affected yellowness, and they inversely impacted lightness and redness.