Model is presented and applied to conventional and ultrasound-assisted oil extraction.

Solid superficial damage is explicitly considered and the particle volume fraction of damaged cells calculated.

Applied to slices and ground seeds and transport parameters associated to the washing and diffusion phenomena obtained.

In conventional extraction physical surface damage was found to be of the order of magnitude of one cell layer.

For ultrasound-aided extraction the model predicted an increase in external mass transfer and amount of damaged cells.