煎炸时间对植物油脂中脂肪酸含量的影响

Effect of frying time on the fatty acids content in vegetable oils

目的探讨不同煎炸时间对大豆油、花生油和芝麻油3种植物油脂脂肪酸含量变化的影响。方法选取煎炸温度为350℃,煎炸时间分别为0.5、1、3、5、7、25 h,用氢氧化钾-甲醇溶液进行甲酯化,并采用气相色谱-质谱法(gas chromatography-mass spectrometry)对脂肪酸甲酯化溶液进行定量分析。结果随着煎炸时间的延长,油脂中总脂肪酸含量呈现递减趋势。其中,油脂中饱和脂肪酸(SFA)的总含量均呈递增趋势,而不饱和脂肪酸(UFA)的总含量均呈递减趋势。结论煎炸25 h后的大豆油、花生油和芝麻油的饱和脂肪酸(SFA)含量分别由19.03%、14.68%、17.54%增至33.01%、23.24%、27.41%,变化率分别为58.45%、34.43%、56.34%,从饱和脂肪酸的变化率来看,花生油相对更稳定。而其不饱和脂肪酸(UFA)分别由80.84%、85.21%、82.39%减少到59.67%、68.97%、69.41%,变化率分别为19.06%、26.18%、15.75%,从不饱和脂肪酸来看,芝麻油更具稳定性。

Objective To explore the effect of frying time on the fatty acids content in soybean oil, peanut oil and sesame oil. Methods Considering the boiling point of this three kinds of oils, the frying temperature was selected at 350℃ in combination with the practical situation of daily at the time of frying. Soybean oil, peanut oil and sesame oil were frying 0.5, 1, 3, 5, 7 and 25 h, respectively, at 350℃. Then, potassium hydrox-ide-methanol solution was added in methyl-esterification reaction and then fatty acid methyl ester solution was investigated for qualitative and quantitative analysis by gas chromatography-mass spectrometry (GC-MS) me-thod. Results The total content of SFA were increasing trend in oil, while the total content of UFA all showed a trend of decline with a prolonged frying time. Conclusion The total content of SFA were increased to 33.01%, 23.24%, 27.41%from 19.03%, 14.68%, 17.54%, respectively, in soybean oil, peanut oil and se-same oil which were fried for 25 h. The rate of change was 58.45%, 34.43%and 56.34%, respectively, indi-cated that peanut oil was relatively more stable. On the contrary, the total content of UFA were declined to 59.67%, 68.97%, 69.41%from 80.84%, 85.21%, 82.39%, respectively, indicated that sesame oil was more stability.