Fracture in potato tuber parenchyma

Experiments have been carried out to assess the fracture behaviour of potato tuber parenchyma tissue from two different varieties (cvs. King Edward and Record) in three different turgor states (turgid, fresh and flaccid). Methods included wedge-penetration fracture tests, razor-blade cutting tests, ball indentation tests and compression tests. Turgor was manipulated by immersion of fresh tissue in osmotica of known concentration, and assessed by means of cell pressure probing. No significant differences in properties were ascribed to the difference in variety. Changes in water status were responsible for appreciable changes in the fracture properties of the tissue. Values of compressive Young's modulus and work of fracture were combined to predict critical crack lengths for different turgor states under given levels of applied stress below the yield stress.