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Food prep technique blamed for Madison sushi restaurant fires

MADISON (WKOW) — A food preparation technique is to blame for fires at two separate sushi restaurants, according to the Madison Fire Department.

In April, a fire caused damage at Sumo Steakhouse and Sushi Bar off East Washington Avenue.

In May, Takara Japanese Restaurant on Whitney Way was damaged because of a fire.

Fire investigators said the incidents are a result of a technique used to create a food product called “crunch” or “crunchy.” It’s a garnish similar to tempura used by restaurants that serve sushi. It is made with water and flour batter. It’s deep-fried and left to drain and cool.

Investigators believe there are three factors that allow this product to self-heat. They include the use of vegetable oil, deep-frying batter and letting it pile up, and leaving it to cool unattended.

Fire officials are reminding the public that cooking oils are known to self-heat under certain circumstances. They are offering a few safety measures should you try to make this or something similar at home.

  • When making “crunch,” DO NOT pile the product in a container where the heat can build, such
    as a metal colander or mesh strainer. Instead, spread out the product on a baking sheet so the heat
    can readily dissipate.
  • DO NOT leave the product to cool unattended.
  • Place the product under a wet-chemical fire suppression hood as it cools.

While previously unknown to fire officials, the reaction turned out to be more common than they thought.

“Once the first identification was started, we started hearing about other fires in Wisconsin, and contacted their investigators,” Kara Nelson, a Fire Investigator with MFD, said. “So it’s been this team effort to find this fire that a lot of people don’t know is a cause.”

She says it’s similar to how hay bale fires start.

Other sushi restaurants in the area say when they make “crunch”, they make it in small batches put it on baking sheets, and even cool it down with a fan.

The fire department says it’s hoping to partner with a lab to learn more about this specific form about spontaneous combustion.

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