Authentication of vegetable oils using isotope mass spectrometry

Abstract

Vegetable oils play an important role in the  human diet. Both the  physiological value of the  product and its cost largely  depend on the  type of processed raw materials. In this  regard, the  establishment of the  type of vegetable raw materials used for the production of vegetable oils is an important area of research in the identification of this product type. To date,  one of the most  informative methods for assessing the authenticity of plant raw materials is the method of isotope mass spectrometry. Thirty  samples of vegetable oils produced from various  raw materials and places  of origin  (Italy, Greece, Spain, Turkey, Armenia, Russia, Slovenia)  were studied. The isotopic ratios of carbon, oxygen  and hydrogen were measured in the  samples. It is shown  that the  samples of corn oil (C4 type of photosynthesis) are characterized by the  highest values  of the  indicator δ13C, from –17.00‰ to –17.73‰. The rest of the studied samples of vegetable oils were produced from C3 plants (grape seed oil, olive, linseed, sesame, pumpkin, mustard, sunflower, etc.). For them, the values of δ13C lie in the range  from –26.60‰ to –31.14‰. Thus, the  method of isotope mass  spectrometry makes  it possible to detect the  introduction of corn oil into  a product produced from plants with C3 type of photosynthesis, even in small  quantities. In addition, this  method enables establishing the introduction of cheap  oils into  corn oil. The values  of the indicators δ18O and δ2H largely depend on the year of harvest and the climatic characteristics of the region where the raw materials grow. Thus, the values of the isotopic characteristics of the δ18O structural components of the oil samples from grape  seeds  produced in Turkey, Armenia and Italy have significant differences (19.40± 0.77‰, 16.55± 0.66‰ and 23.29± 0.93‰, respectively). The values  of the  isotopic characteristics of hydrogen δ2H of the  sample from Armenia differed from the values  of the samples from Turkey and Italy in the direction of a higher content of “light”  isotopes (–189.86± 1.13‰, —163.17 ± 0.97‰ and –160.72± 0.97‰, respectively). The annual monitoring of these values, the creation of a database, as well as the  use of statistical analysis methods will allow in the  future identifying vegetable oils by their geographical origin  with a high degree  of reliability.