高温条件下食用油脂脂肪酸的变化

Fatty acids changes of edible oil in high temperature heating

研究不同加热时间和加热温度对食用油中脂肪酸各组分及其指标的影响。利用气相色谱检测了加热后油脂的反式脂肪酸生成量和各个脂肪酸含量变化,利用2,4-二硝基苯肼对羰基值进行了检测。结果表明,随着加热温度和加热时间的增加,不饱和脂肪酸的含量缓慢下降,饱和脂肪酸的含量上升,其中C16∶0经过210℃3 h后含量增加了0.572 9 g/L,与此相反,C18∶2则下降了2.084 9 g/L。反式脂肪酸的含量和羰基值都呈上升趋势,反式C18∶1和反式18∶2含量经过210℃3 h后分别增加了0.074 3 g/L和0.071 6 g/L,经过210℃3 h加热后羰基值为52.81 meq/kg,并且这种趋势随着温度的升高,变化更加剧烈,尤其在150℃后油脂的品质开始下降迅速,这样不利于人体健康。因此,建议日常烹饪过程中油温控制在150℃以下。

The effects of different heating time and heating temperature on the composition of fatty acids and its indexes of edible oil were researched. The formation of trans - fatty acids and the changes of the content of various fatty acids after heating treatment were quantified by gas Chromatography. The carbonyl value was determined by using 2,4 - dinitrophenylhydrazine. The results showed that when the heating temperature and time increased, the content of unsaturated fatty acids decreased slowly, while the content of saturated fatty acids increased. The content of C16：0 through 3 h heating treatment at 210℃ increased 0. 572 9 g/L,while the content of C18：2 decreased 2.084 9 g/L. The content of trans -fatty acids and the earbonyl value grew up. Trans - C18：1 and trans - 18：2 after 3 h heating treatment at 210℃ increased 0. 074 3 g/L and 0.071 6 g/L, respectively. Carbonyl value after 3 h heating treatment at 210℃ increased to 52.81 meq/kg, and with the increase of temperature,the trend was more intense. Especially above 150℃ ,the quality of oil began to decline rapidly. Therefore,during the daily cooking process, the temperature should be controlled below 150 ℃.