Temperature-dependent changes in the dynamics and diversity of specific spoilage organisms in mackerel and trout fillets: a MALDI-TOF MS-based study

CFU/g for SSOs. Changes in the abundance of genera of SSOs were investigated using a culturomic approach, which involved the identification of colonies by MALDI-TOF MS. Storage temperatures influenced microbial growth, as the time to reach the critical threshold for SSOs was estimated at 8.8 (0 °C) and 3.4 days (4 °C) in mackerel, and 6.7 (0 °C) and 2 days (4 °C) in trout. Potentially histamine-producing bacteria (HPB), quantified only in mackerel samples, also reached higher levels earlier in samples stored at 4 °C. Temperature affected the complexity and succession of SSOs. In mackerel, Psychrobacter initially dominated at 0 °C, then declined with the increase of Pseudomonas and Shewanella. The same pattern occurred more rapidly at 4 °C. Regarding trout, an initial prevalence of Chryseobacterium and Acinetobacter was observed at 0 °C, but from the fifth day Pseudomonas became dominant. At 4 °C, nineteen genera, including bacteria not traditionally associated with spoilage (e.g. Buttiauxella), were detected during the experiment, compared with only thirteen genera for 0 °C samples. Storage at 0 °C remains a reliable method for limiting the growth of SSOs in fish. Culturomics is a valuable approach for capturing the evolution of SSOs during seafood storage and identifying emerging spoilage-associated genera. Further studies on different species are needed to design effective preservation strategies for fishery products.