Response surface methodology was used to evaluate the quantitative effects of two independent variables, namely solvent polarity and ratio of ultrasound power to sonication time, on the antioxidant capacity and total phenolics content (TPC) in two spring rapeseed cultivars: Feliks and Markus. The mean FRAP, DPPH, and TPC results ranged between 1082–5104 µmol Trolox (TE)/100 g and 1203–5528 µmol TE/100 g, 5373–17417 µmol TE/100 g and 3015–15 989 µmol TE/100 g, 252–1258 mg sinapic acid (SA)/100 g and 282–1292 mg SA/100 g for Feliks and Markus varieties, respectively. The quadratic effect of solvent polarity on FRAP, DPPH, and TPC in the examined extracts was about 11, 2, and 7 times greater, respectively, than the quadratic effect of ultrasound power to sonication time ratio. The predicted optimum solvent polarity = 56.8 and 55.6, and US power/US time = 4.0 and 4.2 W/min resulted in FRAP = 5143 µmol TE/100 g and 5503 µmol TE/100 g, DPPH = 16 623 µmol TE/100 g and 15 839 µmol TE/100 g, TPC = 1250 mg SA/100 g and 1259 mg SA/100 g in extracts obtained from Feliks and Markus cultivars, respectively.
Practical applications: Bioactive compounds extracted from rapeseed varieties provide health benefits and have antioxidative properties. The application of ultrasound resulted in an increase in antioxidant extraction from rapeseed. Therefore, it seems worth while to consider the application of ultrasound in the fat industry for the production of rapeseed oils with a high content of antioxidants. The ultrasound‐assisted extraction of antioxidants from rapeseed would make it possible to improve technological processes and consequently reduce processing times and costs. Moreover, the analytical methods used, FRAP, DPPH, and Folin–Ciocalteu, do not require specialized equipment and can be employed by the fat industry laboratories to assess the antioxidant capacity and total phenolics in rapeseed cultivars.
Response surface methodology was used to evaluate the quantitative effects of two independent variables, namely solvent polarity and ratio of ultrasound power to sonication time, on the antioxidant capacity and total phenolics content in two spring rapeseed cultivars. The application of ultrasound resulted in an increase of antioxidant extraction from rapeseed. The low‐cost ultrasonic technology can be employed by the oil processing industry for producing rapeseed oil with a high content of bioactive compounds.