The effect of ultrasound-assisted maceration of selected cold-pressed oils with lyophilized mullein flowers (Verbascum thapsus L.) on their oxidative stability and chemical composition

The study aimed to evaluate the effect of ultrasound maceration of cold-pressed oils with freeze-dried mullein flowers (Verbascum thapsus L.) on their oxidative stability and chemical composition. After the maceration process, oils' were subjected to their oxidative stability (80–120 °C) and their chemical composition, Moreover, oils kinetics parameters were calculated. Maceration enhanced the oxidative stability of the tested oils, particularly linseed and chia oils, from 9.66 to 13.44 h and 4.95 to 8.10 h at 90 °C, respectively. The levels of phenolic compounds and phenolic acids significantly increased, especially in rapeseed oil, from 148.02 to 387.43 (mg GAE 100 g −1) and from 84.16 to 2620.93 (μg 100 g−1), respectively. The oils were also enriched with flavonoids and carotenoids. The oils exhibited higher acid and peroxide value, but lower p-anisidine value after maceration process. The fatty acid composition and the content of sterols and tocochromanols in the oils changed only slightly.