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The interaction between extraction method and antioxidant addition on the oxidative stability of Echium oil was investigated using a factorial design (22). Oil from Echium seeds was extracted using supercritical CO2 (SF) or cold pressing (CP). The oils were supplemented with rosemary extract (N) or left as controls (C) and stored at room temperature for 28 days. Supplementation with an artificial antioxidant (TBHQ) was also included as a positive control. SF extraction and the addition of rosemary extract reduced hydroperoxide concentrations by 50.18% and 57.88%, respectively, compared with the respective controls. The reduction in hydroperoxide levels promoted by rosemary extract was less pronounced when the extraction method changed from CP to SF. Oils obtained by CP showed 13.94% lower tocopherol loss than those obtained by SF, while rosemary extract preserved more 24.08% of tocopherols compared with control samples. A more pronounced difference between antioxidant-treated and control samples was observed under SF extraction than under CP extraction. Factorial analysis revealed that total volatile compounds were influenced by the extraction method, with SF-extracted oils presenting 191.45% higher total volatile levels than CP-extracted oils. The addition of rosemary extract reduced 13.78% total volatile compounds compared with control samples. An interaction between extraction method and antioxidant addition was also observed for total volatiles, with a greater reduction in SF oils than in CP oils. Volatile levels remained stable during storage and were not associated with oxidative progression, suggesting that these compounds were mainly generated during extraction rather than during oxidative reaction. Overall, the extraction method is a key factor influencing oxidative stability and antioxidant performance in Echium oil. The combination of supercritical CO2 extraction with rosemary extract enhanced oil stability and supports its use as a sustainable omega-3 source.
Sisconetto-Bisinotto et al. (Wed,) studied this question.