揚げ油の劣化と使用限界について

抄録

When frying oil is used many times, it is said to lose its flavour gradually and result in a toxic character. First, we explored a practical method of measuring the delimit of used oil. Then we measured the extent of the rancidity of frying oil commonly used in home-cooking. The results are as follows : 1. The Kreis test and the Foaming test are applied as practical methods of measuring the uselimit of frying oil. According to these two methods, the results of the measurement proved to be related with each other. 2. Frying oil used in 250 homes at Oka, Taki-cho, Mie Prefecture was tested. Thirty per cent passed the Kreis test and about 60 per cent was below 40mm in the Foaming test. These data show that in most homes of this area "frequently-used-oil" is still used, with some new oil added. 3. Results of the rancidity experiment by frying doughnuts is shown to infer that the frying oil reaches its use-limit, under the usual home-cooking conditions, when all the frying materials weigh more than the oil.