ボルタンメトリーによる油脂酸価の簡易計測

抄録

For the voltammetric determination of acid values in fat and oils based on the reduction prepeak of 3,5-di-tert-butyl-1,2-benzoquinone (DBBQ), a newly electrolyte cocktail containing 9 mM DBBQ, 48 mM LiCl, and 1.2 mM palmitic acid in 1-butanol was prepared. Also, the electrochemical cell and the voltammetric conditions were optimized. Deoxygenation from the electrolyte cocktail was not required to measure a voltammogram of DBBQ because the reduction peak potential of DBBQ was more positive compared with that of oxygen. The voltammetric prepeak height of DBBQ caused by palmitic acid was found to be linearly related to the palmitic acid concentrations in standard solutions from 0.042 mM to 2.5 mM (r = 0.999). This result showed that the determination of the acid values in fats and oils can be carried out by the present method, ranging from 0.031 mg to 1.85 mg. The analytical result of the acid value in olive oil by the present method was 0.212 mg using the standard addition method, while that by the official titration method of the Japan Agricultural Standards was 0.214 mg. Additionally, the acid values in commercial sesame, corn, grape seed, safflower, salad, and cottonseed oils determined by the present method also agreed with those by the titration method (r = 0.999). In terms of facility, environment-friendliness, and economy, the present method has advantages and thus would be applicable to a sensor to examine the deterioration of fats and oils in routine work.