Temperature and Preparation Time Intervals on Survival of Metacercariae in Pickled Fish (Pla-som).

This study involved two series of independent trials that investigated the storage temperature and time of raw fish to eliminate metacercarial infection in Thai pickled fish. A total of 330 healthy silver barb fishes (30-day posthatch) were infected with cercariae at an inoculation ratio of 50 cercariae/fish. After infection, the fish was reared for 3 months. The first trial was to evaluate the effect of fish storage temperature in the recovery from metacercariae. The infected fishes were randomly divided into five groups and stored at -20°C, 2°C, 4°C, and 8°C or room temperature (as a control) for 24 h. The results showed that at a storage temperature of -20°C, the fish initially had a reduced recovery rate from metacercariae. The second trial investigated the storage time for the recovery of infected fish stored at -20°C for 18, 24, 36, 48, or 60 h and used room temperature as a control group. The results revealed that storing infected fish at -20°C for 48 and 60 h had the lowest recovery rate from metacercariae at 0.00%. In conclusion, storing infected fish at a temperature of -20°C for a period of 48 h or longer could restrict the metacercaria recovery rate. These results were recommended as suitable conditions for the preparation of Pla-som to avoid metacercaria contamination.