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Spontaneous Combustion of Sushi Breading?!?

November 2019

The charred and melted remains of an oil-based fire

There is a little-known, yet extremely common, cause of preventable fires that is affecting restaurant owners across the country. This type of fire specifically plagues the most experienced and enthusiastic chefs in the oriental culinary world. I am talking about those delicious, deep-fried tempura flakes, known as tenkasu or agedama, that are used as breading on sushi rolls. If not stored properly, this crunchy mixture can spontaneously heat up and combust overnight in your kitchen, which is part of the reason why these fires are so devastating.

How Can I Prevent a Tenkasu or Agedama Fire?

  • Do not leave your deep-fried batter in a large pot or bowl

Vegetable, canola, and soybean-based oils tend to self-heat when mixed with other ingredients. Flour is a perfect catalyst. If left unattended, the materials can heat up to the point of ignition after several hours.

  • Be mindful of the temperature outside

These materials already have a nasty habit of getting very hot. Add summer-time heat to the mix and you are asking for trouble.

  • Spread the materials out on a large, flat surface

This will allow the heat to dissipate and spread out more evenly. You never want to contain this material within a confined space.


What Can I Do to Further Prevent Fires?

Nearly all fires can be avoided with regular equipment maintenance or cleaning, proper storage of chemicals and materials, diligent employees, and proper waste disposal. We continue to see issues involved with spontaneous combustion of kitchen towels, and our Loss Control Representatives will recommend that they be stored in airtight metal containers.

According to the National Fire Protection Association, between 2004-2010, the leading cause of fires within eating and drinking establishments was caused by cooking equipment, making up an astonishing 61 percent of the total fires. This means that 6 out of 10 fires could have been prevented.

  Figure 1. Structure Fires in Eating and Drinking Establishments by Major Cause: 2010-2014 Annual Averages (Top 5 Shown). Adapted from

Figure 1. Structure Fires in Eating and Drinking Establishments by Major Cause: 2010-2014 Annual Averages (Top 5 Shown). Adapted from "NFPA's "Structure Fires in Eating and Drinking Establishments"," by Richard Campbell, February 2017, NFPA. Retrieved July 26, 2019, from https://www.nfpa.org/News-and-Research/Data-research-and-tools/Building-and-Life-Safety/Eating-and-drinking-establishments by the National Fire Protection Association

As a large-loss adjuster, I have had the unfortunate privilege of seeing the aftermath of fires first-hand. I am often onsite within twenty-four hours of the destruction, while the origin and cause of the fire is still under investigation. I work closely with the local fire marshals, fire departments, certified fire investigators, and electrical engineers to answer the question that every devastated business owner is reluctantly longing to learn, “What caused this fire?” It is never easy to look an exhausted, emotional, and shell-shocked policyholder in the eye and tell them that it may take up to a whole year for them to open back up to a normal state of business. Sometimes restaurants never recover at all. Insurance cannot replace customer loyalty, so it is crucial to take all the necessary precautions.

You can learn more about insuring your restaurant with ICC by contacting an ICC agent today. The Find an Agent search on our homepage will help you find an ICC agent in your area.

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