A tunnel 2 for the in-line anti-bacterial treatment of plucked poultry carcasses (or other animal carcasses) with a liquid cryogen or a cold gas at a temperature of less than 0° C. has an entrance 18 and an exit 20 for the poultry carcasses. A monorail conveyor 22 extends from the entrance 18 to the exit 20 and passes thorough the tunnel 2. Poultry suspension shackles 24 are able to pass along the conveyor 22. Thus, poultry carcasses are able to be conveyed through the tunnel 2. The conveyor 22 may follow a path which reverses direction at least once.
