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The smoke point of an oil or fat is the temperature at which, under defined conditions, enough volatile compounds emerge when a bluish smoke becomes clearly visible from the oil. At this temperature, volatile compounds, such as free fatty acids, and short-chain degradation products of oxidation come up from the oil. These volatile compounds degrade in air to give soot. The smoke point indicates the temperature limit up to which that cooking oil can be used. The smoke point correlates with the amount of free fatty acid in an oil.〔 It varies widely, depending on origin and refinement. The smoke point of an oil does tend to increase as free fatty acid content decreases and degree of refinement increases. Heating the oil produces free fatty acid and as this heating time increases, more free fatty acids are produced, thereby decreasing smoke point. It is one reason not to use the same oil to deep fry more than twice.〔 Intermittent frying has a markedly greater effect on oil deterioration than continuous frying.〔Amit K. Das, et al, http://www.slideshare.net/amitkdas12/study-of-oil-deterioration-during-continuous-and-intermittent-frying〕 Considerably above the temperature of the smoke point is the flash point, the point at which the vapours from the oil can first ignite when mixed with air. The following table presents smoke points of various fats: ==See also== * Boiling point * Flash point * Fire point * Kindling point (Autoignition temperature) 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Smoke point」の詳細全文を読む スポンサード リンク
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