Fluorescence and UV-VIS Spectroscopy to Determine the Quality Changes of Rapeseed Oil Fortified with New Antioxidant After Storage Under Various Conditions - Food Analytical Methods

This work focused on the application of synchronous fluorescence (SF) spectroscopy, excitation-emission matrix (EEM) fluorescence spectroscopy and modified UV-VIS methods for characterization of oxidative status and antioxidant activity (AA) of refined rapeseed oils fortified with the novel antioxidant octyl sinapate (OSA) at two concentrations and butylated hydroxyanisole (BHA) stored in different types of packages under various storage conditions. Quality parameters such as amounts of the primary and secondary oxidation products in rapeseed oils increased after storage under various conditions, whereas the AA of oils decreased. However, OSA strongly inhibited the generation of primary oxidation products in oils exposed to light. The AA of rapeseed oil with 0.5% of OSA packed in transparent glass after exposure to light was 6 times higher than the AA of non-supplemented oil. Moreover, the intensities of bands attributed to tocopherols and phenolic compounds decreased during storage depending on the storage conditions, but characteristic peaks for generation of oxidation products appeared. Interestingly, the fluorescence spectra of oil fortified with 0.5% of OSA contained the information of a new fluorescent product. Moreover, the potential usefulness of EEM to study the effect of antioxidants on degradation of stored rapeseed oils was demonstrated. Fluorescence spectroscopy can be used to investigate the oxidation state of rapeseed oils packed in various containers during storage at different conditions. The addition of the lipophilic antioxidant to rapeseed oil effectively delayed the oxidation process and significantly increased its AA.