Raw Frozen Seafood Case Study

The characterisation of the bacterial flora of raw frozen cultured seafood was performed to determine a naturally occurring bacterial indicator of antimicrobial resistance in seafood (Paper I). Fresh seafood is processed to produce retailed raw frozen cultured seafood for consumers. The extent to which the microflora of raw frozen cultured seafood differ from the microflora of harvested seafood is not clear. However, different bacterial species have been isolated from fish-processing environments, e.g. Exiguobacterium spp. has been isolated from a fish processing plant in Japan (Yumoto et al., 2004) and Staphylococcus spp. in food is often associated with human contact. Furthermore, due to the halophilic nature of Staphylococcus spp. (Simon
In contrast to poultry and pork, in seafood processing there are more handling and processing steps and exposure to water and different concentrations of chemical solutions from reception of raw produce to packaging (Hossain et al., 2010; Thi et al., 2013). The long chain of seafood processing allows bacterial contamination of seafood during different steps of the processing as compared with pork and poultry produce, suggesting a change in the structure of bacterial flora in raw frozen processed seafood (Hossain et al., 2010; Thi et al.,
The bacterial flora of raw frozen processed seafood mainly changes after processing. The extent of changes in natural bacterial flora takes place in the processing plant due to repeated exposure to water and chemicals where bacterial flora from water, the environment and humans are introduced to the products (Hossain et al., 2010; Thi et al., 2013). It has been found that the initial biota of herring fillet are dominated by Shewanella putrefaciens and Pseudomonas species. In addition, E. coli, Staphylococcus aureus and Clostridium perfringens have been identified from raw frozen seafood. A prevalence study of Aeromonas on catfish in a processing plant showed the predominance of Aeromonas and Pseudomonas spp., Staphylococcus aureus, faecal coliform, E. coli and Salmonella in different frozen processed seafood (Thi et al., 2013). Contamination of processed seafood might occur from the plant equipment at different stages of processing. Several bacterial species identified from plant equipment include Pseudomonas, Neisseriaceae, Enterobacteriaceae, Coryneforms, Acinetobacter, Alcaligenes, Psychrobacter, Staphylococcus, lactic acid bacteria and yeasts (ICMSF, 2005). Good sanitation practices in the processing plant prevent seafood products from becoming contaminated during raw processing, and rapid freezing retards