Prepared frozen foods on the market such as hamburg cutlets, chiken balls, croquettes, gyoza (dumplins stuffed with minced pork), cheese rolled eggs, fried fish and fried bean curd were thawed in frying oil at 150°C-180°C and tested to investigate the following : 1) the change of the properties of frying oil, 2) the rise in internal tempetrature of the samples, and 3) the taste in color, appearance, crispness and flavor of the samples.
Deterioration of frying oil was the worst in thawing fried bean curd ; the best in croquettes. Deterioration of frying oil was much faster at 150°C, and color of the samples was more colorful at the same temperature, but appearance, crispness and flavor were not good. It means there was some relationship between deterioration of frying oil and the taste.
The data showed that thawing chiken balls, hamburg cutles in frying oil at 150°C was preferable and other samples at 180°C, and that the internal temperature of the samples must be kept at not less than 80°C.