Examination of the modified Villavecchia test for detecting sesame oil

The official methods of the American Oil Chemists' Society recommend the modified Villavecchia test Cb 2-40 for detecting sesame oil in animal and vegetable fats and oils. The test is based on the reactivity of sesamol and sesamolin to furfural under acidic conditions. Although the contribution of sesamol and sesamolin to the reaction has been reported, little information is available on how the test performed with oils prepared from different sesame varieties or for effects of roasting conditions of seeds. The objective of this study was to clarify the contribution of various lignans to the Villavecchia test results. Chromogenic products of the Villavecchia test with sesame oil prepared from different varieties of sesame seeds gave different absorbance intensities at 520 nm, and the absorbance intensities were positively correlated with the content of sesamolin in sesame oil. Roasting conditions affected the content and concentration of lignans in sesame oil, and consequently the corresponding chromogenicity of the Villavecchia test. Roasting seeds at 230 C for 5 min caused a significant loss of sesamolin in oil, the level of sesamol increased, and the absorbance intensity at 520 nm of the corresponding Villavecchia testing product also increased. Roasting seeds at 280 C for 5 min caused loss of sesamin and the disappearance of sesamolin from the resultant oil, whereas the level of sesamol increased. These results provide guidance for determining the utility of the Villavecchia test for detecting sesame oil in mixtures of other foods.