MICROBIOLOGICAL EFFECTS OF ON-BOARD FISHING VESSEL HANDLING IN MERLUCCIUS MERLUCCIUS

The purpose of the present study was to determine the impact of different manipulation techniques applied on board fishing vessel, on the microbiological quality of the flesh of European hake (Merluccius merluccius) during storage at +3°C ± 1°C for a time (T) of 10 days after landing (T1-T10). Samples of fish were taken from a fishing vessel of the Adriatic Sea and from one of the Tyrrhenian Sea, treated on-board under different icing conditions: 1) a low ice/product weight ratio and 2) an optimal ice/product weight ratio, up to 1:3 (3). Spoilage bacteria as Total Bacterial Count (TBC) and specific spoilage bacteria as Sulphide Producing Bacteria (SPB) were enumerated in fish flesh as Colony Forming Units (CFU/g) on Plate Count Agar and Lyngby Agar at 20°C for 3-5 days. TBC of the Adriatic fishes (gutted on-board) resulted 103 UFC/g at T1-T6, and 104-105 at T10, whereas TBC of the Tyrrhenian fishes (not gutted on-board) resulted 10-102 UFC/g at T2- T3, 103 at T6, and 104-105 at T10. SPB resulted 10- 102 UFC/g at T1-T6, and 103- 104 at T10, with absolute values higher in the Adriatic fishes, in respect with the Tyrrhenian fishes, and in the low icing conditions in respect with the optimal icing condition. At the experimented condition, the lowering of the microbiological quality of fish flesh during storage, seems to be more dependent on the gutting versus not gutting on-board practice rather than on the low versus optimal icing treatment.