Design of the Prototype Device to Kill Anisakis Using Pulsed Power Technology

Anisakis is a nematode parasite that is found in many fishery products, and can cause human parasitic infection called anisakiasis when raw fish with live anisakis is eaten. It is estimated that about 20,000 cases of anisakiasis occur annually in Japan. The only practical way to kill anisakis without heating was freezing, but freezing causes deterioration of quality, such as deterioration of texture and color of fish meat. As an alternative method to freezing, we have shown that anisakis in fish meat can be killed without heating by repeatedly applying pulsed high current to the fish meat, and that the quality of pulse-treated fish meat is almost the same as that of untreated meat. A prototype of a device to kill anisakis using pulsed power technology has been fabricated and is described here. The temperature rise of fish meat has a significant impact on the quality of fish meat, so in order to apply the pulsed current while keeping the temperature of the fish meat as low as possible, we manufactured a treatment tank that can be filled with 180 liter of buffer saltwater, placed the fish meat between parallel plate electrodes installed in the treatment tank, and applied pulse current while agitating it with water flow created by pumps. Using Taguchi methods, parameters such as saltwater conductivity, charging voltage, and capacitance necessary for killing anisakis were studied, and specifications of the equipment were determined. In addition, to ensure the safety of workers, all parts of the device that might be touched by workers were made to have grounding potential. The device was installed at a seafood processing factory. Tests were conducted and it was confirmed that all anisakis were killed. Currently, the company sells horse mackerel treated with this device to some of its customers, and it is highly evaluated for its safety and quality.