Two Madison, Wisconsin sushi restaurants collectively sustained about $575,000 worth of damage resulting from two fires in April and May. The Madison Fire Department investigated the blazes, which struck Sumo Steakhouse and Sushi Bar. Their conclusion? Sushi crunchies—those delicious crumbly tempura bits atop some sushi rolls—spontaneously combusted and set the restaurants aflame. Truly.
The Wisconsin State Journal reports the fire department issued a warning yesterday alerting restaurants to the potential for sushi crunchies to “spontaneously catch fire when not stored properly.” Investigators found five incidents of fires caused by sushi crunchies nationally.
“The fires were caused by a food preparation technique where oil used to make a tempura-like crunch self-heats and spontaneously combusts,” fire department spokeswoman Cynthia Schuster told the Journal.
While the incident may seem odd, spontaneous combustion—especially of dry material, potentially near fuel and hot surfaces—is a real phenomenon. Basically, a material begins to heat, whether through oxidation or bacterial fermentation, and ignites when the heat is unable to escape. Materials with high oil contents—including pistachio nuts, oddly enough—are especially prone to combustion.
So please, if you make our recipe for tempura crunchies, heed the Madison Fire Department’s advice and spread them on a baking sheet to cool completely and don’t store them in a container where heat can build.