粮食脂肪酸值测定影响因素分析及优化

Analysis and Optimization of Factors Influencing the Determination of Fatty Acid Value in Grain

影响粮食脂肪酸值测定结果的因素很多,对振荡器振幅、实验用水、指示剂、标准滴定溶液四个方面进行研究,探讨粮食脂肪酸值测定的优化方法。研究结果表明,振荡器振幅对测定结果存在显著影响,用三级水、百里香酚蓝指示剂、水溶剂氢氧化钾标准滴定溶液代替现行方法中的不含CO_( 2)的蒸馏水、酚酞指示剂、95%乙醇溶剂氢氧化钾标准滴定溶液对测定结果不存在显著影响。经优化后的方法简化了实验用水的制备,提高了测定效率;滴定终点的颜色变化易于观察,解决了“终点判定难”的问题;手工滴定法适用范围更广,不仅适用于普通粮食的脂肪酸值测定,还适用于其他“有色”粮食的脂肪酸值测定;水溶剂氢氧化钾标准滴定溶液的长期稳定性、短期稳定性都优于乙醇溶剂氢氧化钾标准滴定溶液,减少了因标准滴定溶液带来的误差。优化后的方法易于掌握,具有推广价值。

Many factors affected the determination result of fatty acid value in grain.In this paper,the oscillator amplitude,experimental water,indicator and standard titration solution were studied,to further explore the optimization method for the determination of fatty acid value in grain.The results showed that the amplitude of the oscillator had a significant effect on the measurement results.There was no significant effect on the determination results by replacing the distilled water without CO_( 2),phenolphthalein indicator,95%ethanol solvent potassium hydroxide standard titration solution with the third-grade water,thymol blue indicator and water solvent potassium hydroxide standard titration solution.The optimized method simplified the preparation of experimental water and improved the determination efficiency;the color change at the end of titration was easy to observe,which solved the problem of‘difficult to determine the end point of titration’;the manual titration method had a wider scope of application,and it was not only suitable for the determination of fatty acid value of ordinary grains,but also suitable for the determination of fatty acid value of other"colored"grains.The long-term and short-term stability of KOH standard titration solution prepared with distilled water was better than that KOH standard titration solution prepared with ethanol solvent,which reduced the errors caused by standard titration solution.The optimized method was easy to master and had the promotion value.