A green one-pot method for simultaneous extraction and transesterification of seed oil catalyzed by a p-toluenesulfonic acid based deep eutectic solvent

•A green one-pot method for simultaneous extraction and transesterification of seed oil was proposed.•Novel p-toluenesulfonic acid based deep eutectic solvents were prepared successfully.•Central composite design (CCD) and response surface methodology were conducted.•High extraction and transesterification yields of oil demonstrated the eff ;ectiveness of the prepared catalyst.