What is a Sushi Crunch Fire?

Deep-fried tempura flakes are a key ingredient sprinkled on sushi rolls for crunch. Known as agedama or tenkasu, Japanese for “tempura dregs,” they have been linked to a series of restaurant fires in multiple states.

Kara Nelson, a fire investigator in Madison, Wisconsin, worked with the Bureau of Alcohol, Tobacco, Firearms and Explosives to pinpoint the cause of the blazes which were caused by spontaneous combustion.

What is Spontaneous Combustion?

Spontaneous combustion is the ignition of organic matter without apparent cause, typically through heat generated internally by rapid oxidation. It can happen in hay bales and mulch piles. And now in tempura flakes.      

The crunchy flakes are made by ladling drops of batter into a deep fryer. Canola and soybean oils are commonly used which both have a propensity to self-heat. In addition, keeping the mix densely piled in a pot or bowl does not allow the heat to dissipate. So, the heat builds and builds. Once it hits ignition temperature, a fire occurs.

Learn more about kitchen fire prevention by reading, ‘8 Steps to Reduce the Risk of Fire at Your Bar or Restaurant.’

How to Reduce the Risk of a Sushi Crunch Fire

1. Right after the tempura flakes are made, don’t leave them unattended.

It can take anywhere from three to 10 hours for the heat process to start before it goes into ignition. Leaving the deep-fried flakes in a pot is a recipe for a fire. Be very careful about cool down. It’s recommended to spread the fried dough out on a baking sheet so the heat can dissipate.

2. Do not make tempura flakes at night, but instead, prepare it in the morning.        

Preparing early in the day ensures you’re there to observe and take action to prevent a fire.

3. Complete regular maintenance of equipment following manufacturer cleaning guidelines.

Proper maintenance of cooking equipment also reduces the hazard of kitchen fires. Review Society’s recommended Cooking Equipment Maintenance Requirements to reduce the hazard of a fire in your restaurant kitchen.

Sushi Crunch Fires in Wisconsin

A fire in Madison, Wisconsin happened on April 5, 2019 at Sumo Japanese Steakhouse & Sushi Bar where security camera footage showed smoke billowing in the kitchen six hours after the crunch mix had been left in a metal colander to cool. Four hours later, flames engulfed the kitchen. The second fire broke out at Takara Japanese Restaurant on May 9, 2019.

No one was injured in the two fires, but damages from both together totaled at least $575,000.

Protecting Your Business from Costly Fires

With extensive experience in insuring restaurants and bars, Society can provide policyholders with a tailored insurance policy and exclusive safety resources to reduce the risk of financial loss or injury. Get in touch with a Society agent today to learn more about how to best protect your business from fires and other mishaps.

Browse our Fire Prevention blog series or Risk Control Library for more information on maintenance requirements, the risk of selling flaming alcohol and more.