Viscoelastic Properties of Storage Tissues from Potato, Apple, and Pear

SUMMARY Slices of potato tubers were subjected to cyclic elongation, stress relaxation, and breaking in an Instron materials‐testing instrument. Cubes of such tissues and of ripe, fruits of pears and apples were subjected to cyclic compression and stress relaxation. The time required for 20% relaxation of the stress was progressively longer with each of 3 cycles. Cycling increased the apparent values of Young's modulus, E , for slices treated in acetone, treated in acetone and rehydrated, and frozen and then thawed, but decreased values for slices soaked overnight in H 2 O at 6°C. With potato slices and cubes, treatments which wilted them resulted in shorter times for a 20% relaxation of stress. Cubes of pear and apple soaked 3 hr in H 2 O tended to disintegrate and also showed much shorter times for relaxation of stress than cubes treated in 0.5 M sucrose. The general features of all curves were qualitatively similar, except that compressing cubes of potato tubers beyond a stress of about 0.9 Kg/cm 2 resulted in a sharp, reversible increase in apparent values of E .