| 薛斌,曹文明,包杰，等.自动电位滴定法测定米糠油酸值的研究[J].中国油脂,2014,39(11):.[XUE Bin,CAO Wenming,BAO Jie，etc.Detection of acid value of rice bran oil by automatic potentiometric titration[J].China Oils and Fats,2014,39(11):.] |
| 自动电位滴定法测定米糠油酸值的研究 |
| Detection of acid value of rice bran oil by automatic potentiometric titration |
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| DOI： |
| 中文关键词: 自动电位滴定 米糠油 酸值 谷维素 |
| 英文关键词:automatic potentiometric titration rice bran oil acid value oryzanol |
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| 摘要点击次数: 1185 |
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| 中文摘要: |
| 为了克服传统的人工指示剂滴定法在测定米糠油酸值过程中，米糠油本身的颜色和高含量的γ-谷维素对测定结果的严重干扰，采用自动电位滴定法，根据经典的酸碱滴定理论，采用二次作图法，在滴定的同时由联机电脑实时同步绘制酸碱滴定的pH-滴定体积曲线及其相应的一阶微分曲线，以这些曲线上游离脂肪酸发生中和反应引起的“pH突跃”为滴定终点的判定依据，建立米糠油酸值测定的自动电位滴定法。结果发现，自动电位滴定法能够准确区分游离脂肪酸和γ-谷维素各自的滴定终点，从而排除γ-谷维素对米糠油酸值测定的干扰。对比实验发现，除了米糠油外，自动电位滴定法对各类食用植物油酸值的测定结果与传统的人工指示剂滴定法的测定结果十分接近；但对于米糠油，人工指示剂滴定法的酸值（KOH）测定结果一般偏高0.3~1.0 mg/g。表明自动电位滴定法更能准确地测定米糠油的酸值。 |
| 英文摘要: |
| In order to overcome the severe interferences of color and high content γ-oryzanol in the detection of acid value of rice bran oil by traditional manual indicator titration method, according to the classical theory of acid base titration, using methods of automatic potentiometric titration and “second graph”, a detection method of the acid value of rice bran oil was established. Using this method, the pH-titration volume curve and corresponding first-order difference curve of acid base titration were drawn by computer real-timely and synchronously, then the “pH jump” in these curves, which was caused by the neutralization of free fatty acids, was taken as the foundation for judgment of titration end point. The results showed that the titration end points of free fatty acids and γ oryzanol could be distinguished correctly by automatic potentiometric titration method, therefore the interference of γ oryzanol in the detection of acid value of rice bran oil could be excluded. By contrastive experiments, it was found that the acid values of many kinds of vegetable oils detected by automatic potentiometric titration method were very close to those detected by traditional manual indicator titration method; while the acid value of rice bran oil detected by traditional manual indicator titration method was 0.3-1.0 mgKOH/g higher than that detected by automatic potentiometric titration method. Therefore, the acid value of rice bran oil could be detected accurately by automatic potentiometric titration method. |
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