Changes in physicochemical properties, moisture distribution and volatile flavor compounds of yellow catfish: The roles of dominant spoilage bacteria

The spoilage potential of three dominant bacterial species (Shewanella putrefaciens, Pseudomonas fragi, and Acinetobacter sp.), which were isolated from spoiled yellow catfish, were investigated. Physicochemical properties, moisture distribution, and volatile flavor compounds were assessed in yellow catfish inoculated with individual bacterial species. Compared to Acinetobacter sp., Shewanella putrefaciens and Pseudomonas spp. exhibited a greater capacity for producing produce total volatile basic nitrogen (TVB-N) and total viable counts. Sensory results revealed that a significantly (P < 0.05) higher b* value in yellow catfish group inoculated with Shewanella putrefaciens compared to other groups, resulting in discoloration. Low-field nuclear magnetic imaging results indicated a decline in the proportion of bound and free waterof during extended storage, accompanied by an increase in immobilized water. The yellow catfish group inoculated with Shewanella putrefaciens exhibited the lowest P23 and the highest T23, which indicated Shewanella putrefaciens changed the water holding capacity of fish samples. Gas chromatography-ion mobility spectrometry (GC-IMS) analysis of volatile flavor compounds demonstrated the pronounced capability of Pseudomonas fragi to generate 1-octen-3-ol, closely associated with ketones production and contributing significantly to the odor of yellow catfish during spoilage. In addition, E. coli was found to have the ability to spoil yellow catfish and generate unfavorable volatile flavor compounds. This research enhances the comprehension of yellow catfish spoilage and preservation.