The use of the so-called ‘tubs’ for transporting and storing fresh fishery products

On-land transport/storage of fresh fishery products (FFP) for up to 3 days in ‘tubs’ of three-layered polyethylene filled with freshwater and ice was compared to the currently authorised practice (fish boxes of high-density poly-ethylene filled with ice). The impact on the survival and growth of biological hazards in fish and the histamine production in fish species associated with a high amount of histidine was assessed. In different modelling scenarios, the FFP are stored on-board in freshwater or seawater/ice (in tubs) and once on-land they are ‘handled’ (i.e. sorted or gutted and/or filleted) and transferred to either tubs or boxes. The temperature of the FFP was assumed to be the most influential factor affecting relevant hazards. Under reasonably foreseeable ‘abusive’ scenarios and using a conservative modelling approach, the growth of the relevant hazards (i.e. Listeria monocytogenes, Aeromonas spp. and non-proteolytic Clostridium botulinum), is expected to be <0.2 log10 units higher in tubs than in boxes after 3 days when the initial temperature of the fish is 0°C (‘keeping’ process). Starting at 7°C (‘cooling-keeping’ process), the expected difference in the growth potential is higher (<1 log10 for A. hydrophila and <0.5 log10 for the other two hazards) due to the poorer cooling capacity of water and ice (tub) compared with ice (box). The survival of relevant hazards is not or is negligibly impacted. Histamine formation due to growth of Morganella psychrotolerans under the ‘keeping’ or ‘cooling-keeping’ process can be up to 0.4 ppm and 1.5 ppm higher, respectively, in tubs as compared to boxes after 3 days, without reaching the legal limit of 100 ppm. The water uptake associated with the storage of the FFP in tubs (which may be up to 6%) does not make a relevant contribution to the differences in microbial growth potential compared to boxes.