Seven fires at sushi restaurants in the US were caused by spontaneously combusting tempura flakes, investigators have found.<br />A reaction between oxygen and oils used in tempura batter caused fires in five Wisconsin restaurants.<br />There were also fires in Minnesota, Virginia, and even Canada.<br />A fire investigator told ABC News: "The oil will combine with the oxygen in the air and in that chemical process, it releases heat."<br />The tempura flakes are also known as "crunch," or "tenkasu" in Japanese. <br />
