How did frogs get into food sold in Japan and are they dangerous?

May 27, 2023 (Mainichi Japan)

Japanese version

TOKYO -- Frogs were recently found in a salad and noodles sold at a supermarket and udon store in Japan. The Mainichi Shimbun interviewed the people involved and experts to find out how the frogs got into the food and whether it is dangerous to eat them by mistake.

The first incident occurred on May 11, when a customer who purchased a salad at the Ario Ueda branch of supermarket chain Ito-Yokado in Ueda, Nagano Prefecture, reported that the salad was contaminated with a frog.

The manufacturer of the salad, Daily Hayashiya Co. based in the prefectural city of Matsumoto, on May 16 identified the creature as a 2- to 4-centimeter-long Japanese tree frog.

The local public health center is investigating the details, but the manufacturer believes that the frog was mixed in with lettuce or other vegetables and failed to be removed in the process of washing by machine or visually removing foreign objects. The company has strengthened its countermeasures, such as increasing the number of workers in the foreign object removal process from one to three.

Meanwhile, at the Isahaya branch of the udon restaurant chain Marugame Seimen in Nagasaki Prefecture, a frog was found in a take-out product that was sold on May 21. The item belongs to the chain's new "Marugame Shake Udon" line, which was released on May 16, and had just begun to gain popularity.

Marugame Udon Inc. conducted on-site inspections at all of its suppliers' factories that handle raw vegetables, believing that the contamination occurred at a vegetable processing plant. Despite strengthening its inspection system, the company announced on May 25 that it would suspend sales of some products, including the ones in question, for the time being. It had earlier decided to halt sales until May 25.

Why have frogs been found in food in succession? According to Taisei Nishi, a keeper at KawaZoo in the Shizuoka Prefecture town of Kawazu, which breeds and exhibits more than 120 species of frogs, May to June is the breeding season for frogs, when the number of small insects they feed on increases. It is also their most active time of the year.

Frogs also eat moths and other insects that congregate around streetlights at night. "It could be that they were attracted to the window lights of a factory and somehow ended up inside the facility," Nishi said.

According to a lettuce farmer in the northern Kanto region, frogs and other insects are more likely to get into the lettuce leaves in search of warmth during the night when the outside temperature drops.

If a person touches the mucous membranes with hands that have touched a Japanese tree frog, it is toxic, causing skin irritations and rashes. So is there any danger if one eats a frog without being aware of it? Nishi answered, "If you eat it raw, you could get sick."

(Japanese original by Takeshi Terada, Digital News Group)