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Evaluating the Thymoquinone Content and Antioxidant Properties of Black Cumin (Nigella sativa L.) Seed Oil During Storage at Different Thermal Treatments
Black cumin seeds (Nigella sativa) and black cumin seed oil (BCSO) exhibit various pharmacological activities, most of which are attributed to the presence of thymoquinone (TQ). TQ, however, is characterized by low stability at elevated temperatures and instability in aqueous environments. In this study, the spectroscopic properties of TQ were used to monitor changes in TQ content in BCSO subjected to thermal exposure. Simultaneously, the influence of the presence of TQ on the antioxidant properties of this oil was determined. The used spectrofluorimetric and chromatographic method quantified the presence of TQ. The antiradical properties of the oil in different stages of thermal oxidation degradation were determined by the DPPH method. The measured antiradical activity of the oil, depending on the exposure conditions used, revealed the difference correlated with the content of the TQ. However, the presence in BCSO of other bioactive components, like phenols, had a more significant influence on its total antioxidant capacity. Furthermore, our study, for the first time, focused on the rise in TQ content in the oil during thermal storage, indicating a new method to enhance the TQ content in BCSO.
Impact of Bird Cherry (Prunus padus) Extracts on the Oxidative Stability of a Model O/W Linoleic Acid Emulsion
The delivery and uptake of adequate doses of a number of active compounds, including selected saturated and unsaturated fatty acids (frequently in the form of emulsion systems), is crucial to maintaining a healthy diet. The susceptibility of acids to oxidation and the time stability of emulsions are factors limiting their shelf life and storage time. Those parameters could be improved using selected additives, including antioxidants. In this study, we examined the influence of different bird cherry extracts (varying in the content amounts of bioactive compounds) on the oxidative stability of a model O/W linoleic acid emulsion, using C11-BODIPY581/591 as a fluorescent indicator. We also examined the effect of these extracts on the physicochemical properties of the emulsions and the time stability of the produced emulsion using the dynamic laser scattering technique. The antioxidative efficacy of extracts differed significantly, depending on the extraction method and conditions. The observed differences in the results could be attributed to variations in the specific compositions of the extracts used, which were more or less rich in terms of antioxidants or their synergistic effects. Our results indicated that acetone extract was the most effective with regard to both the oxidation stability and time degradation tests of the emulsions produced. Moreover, the addition of gallic acid did not always have a positive effect on the abovementioned properties.