Fried soybean curd (Abura-age) is one of the favorite foods among Japanese. In a Previous paper, the authors observed the presence of a toxic dimer of triglyceride in oils which were used for frying of some foods, especially in rapeseed oil used for Abura-age.
In order to judge the quality of frying oil used for Abura-age, some more samples were analyzed. The used soybean oils were collected from Aburaage manufactures. Analytical data indicated that most of oils were deteriorated and two of them contained fairly high amounts of toxic dimer of triglyceride (2.4 and 1.1%, respectively).