Detection of adding vegetable oils (palm, soybean and corn) adulteration in olive oil by using High Performance Liquid Chromatography and tocopherols and tocotrienols profile

Olive oil due to its unique properties and characteristics in terms of nutrition has a very high and well-known position in various societies, but due to the high price of this product is always threatened by all kinds of fraud. Tocopherols and tocotrienols are present in small amounts (about 0.35%) in fats and oils. In this study, the fraud of adding vegetable oils (palm, soybean and corn) to olive oil was investigated by comparing the profiles of tocopherols and tocotrienols using HPLC (High-Performance Liquid Chromatography). The mixture statistical design was used to design experiments related to the measurement of tocopherols. After dissolving in n-hexane, the counterfeit oil samples were injected into HPLC with NH2 column chromatography and 294 and 320 nm fluorescence detectors, respectively, for stimulation and diffusion to identify and analyze tocopherols and tocotrienols. Among all tocopherols and tocotrienols, alpha-tocopherol was predominant in olive oil. Therefore, if combined with other oils, the initial composition of tocopherols changes. Among the oils added to olive oil, palm oil had a very significant effect on the peak area of the tocotrienols. Palm and corn oil had a significant effect on the beta-tocopherol peak. In the mixture of olive oil with corn and soybean oil, the amount of gamma-tocopherol increased significantly. Soybean oil had a significant effect on the peak of delta-tocopherol. Therefore, it can be concluded that delta-tocopherol is an indicator of fraud in adding soybean oil to olive oil. The results showed that there is a significant relationship between the amount of tocopherols and tocotrienols and the fraudulent addition of palm, soybean and corn oils to olive oil. Therefore, the proposed method is a suitable method for identifying and determining fraudulent olive oil.