Analytical study of turgor pressure in apple and potato tissues

• A generalized form of a strain energy function is proposed.
• A mathematical relation between turgor pressure and stretch ratio is developed.
• The developed relation shows good fit with experimental data.
• Effects of turgor pressure on cell walls of apple and potato tissues are discussed.

Mechanical injuries are the main cause of damage (such as bruising) and loss of quality of fruit and vegetables, occurring mainly from mechanical forces during compression, vibration and impact loads. Apples and potatoes are susceptible to external and internal pressures, which causes bruising and fracture in soft tissues. The study of turgor pressure and the compressive stiffness of apple and potato tissues is essential to understand their fracture strength against external and internal pressures. In the present study, a generalized form of a strain energy function is proposed, and a relation between turgor pressure and stretch ratio is developed by considering its appropriate form. It is considered that the tissues are isotropic, incompressible, homogeneous, and show hyperelastic behavior. The Levenberg–Marquardt algorithm was used for regression analysis to calibrate the material constants by correlating predicted and experimental values of turgor pressure and stretch ratio for apple and potato tissues. A good fit of the developed relation to experimental data was obtained with the coefficients of determination of 98.02% for apple and 98.0% for potato.