A new way for the oil plant biomass valorization: Polyphenols and proteins extraction from rapeseed stems and leaves assisted by pulsed electric fields

This work aims at investigating the effects of pulsed electric field (PEF) on the extraction of polyphenols and proteins from rapeseed (Brassica napus L.) stems and leaves. The PEF (0.2-20 kV/cm) was applied on fresh rapeseed stems (diameter, d = 6 mm; thickness, h = 10 mm) and leaves (surface, S = 10 × 10 mm2). The PEF-induced cell membrane damage (Z) of rapeseed tissue was studied. The PEF (5-20 kV/cm) increased the extraction of total polyphenols from rapeseed stems and leaves. Treatment at 5 kV/cm resulted in the highest polyphenols purity. In addition, the data evidence that the polyphenols content in rapeseed stems and leaves decreased (≈74%) as plant maturity advanced while the change for protein content is more gentle (≈35.6% decrease). Results of the maturation effect may be useful to determine the optimum harvest time for the rapeseed by-products valorization.