Determination of tocopherol content in vegetable oils as quality parameter
2018
Basic, Milica (https://orcid.org/0000-0002-6267-0419) | Basic, Zorica | Djordjevic, Brizita (https://orcid.org/0000-0002-4582-0809)
Vegetable oils are characterised with high tocopherol content. Depending on way of production and usage, that content can be preserved or diminished. On our market exists more and more versatile offer of vegetable oils with declared tocopherol content. Through a correct usage of this foodstuff, it is possible to the significant extent satisfy vitamin E daily needs. Our aim was to determine tocopherol content in esculent vegetable sunflower and olive oils from our market using HPLC method. Esculent vegetable oils from retail, of various origin and way of production (a total of 11) were analyzed. For a successful determination of tocopherol content in foodstuffs of complex composition it is necessary to perform multiple sample purification, while for a determination in vegetable oil a liquid/liquid extraction is recommended, after alkaline hydrolysis. A n-hexan extraction was applied, extract vaporization and reconstitution in methanol using membrane filtration. Separation was performed using RP-HPLC method with fluorescent detector with changeable wavelengths. For tocopherol detection 95% ethanol was applied as mobile phase, with 1,0 mL/min flow rate and with 295 nm wavelength for excitation and with 330 nm wavelength for emission. Fluorescence detector selectivity and sensitivity enabled detection of α-, ß+γ- and δ- tocopherols in analyzed oil samples. Тocopherol content in the oils of several different manufacturers present on the domestic market, in 2017, ranges from 61.22 to 954.1 mg/kg. A total of 44% of them meet the requirements of the regulation (declarations, or the Rulebook on quality). The high content of tocopherol in oil produced by physical refinement confirms the justification of this processing procedure.
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