Fracture forces of different seed coats, nut shells and hard inner drupe shells (endocarp, “fruit stone”); all specimens were tested in compression in the as-received state without additional drying with a cross-head speed of 5 mm/min.

They were oriented with their sutures vertical to the loading direction and their shorter dimension parallel to the loading direction (fig. 1). “n” denotes the number of specimens tested. All values are mean values plus/minus standard deviations, if not denoted otherwise.