Effect of turgor pressure on the cutting energy of stored potato tissue

Potato tissue samples with varying cell turgor pressures were prepared by soaking them in mannitol solutions (0 M to 0.9 M). Increased concentration of mannitol in the soaking solutions decreased the cell turgor pressure in potato tissues, providing samples with varying degrees of turgidity or plasmolysis. The firmness of potato tissues with different turgor pressures was periodically examined over a 12-week period using cutting tests. The occurrence of incipient plasmolysis was evident after soaking in 0.7 M mannitol solution as supported either by microscopic observations or cutting energy values. The cell turgor pressure of unsoaked tissue decreased during the first 2 weeks, increased between 2 and 4 weeks and finally decreased again up to 12 weeks. The cutting energy of unsoaked tissue showed an inverse trend between 2 and 8 weeks, demonstrating the ability of this mechanical parameter to detect the increase of cell wall stiffness as a function of storage time.