COMPRESSING BEHAVIOR AND TEXTURE EVALUATION FOR POTATOES PRETREATED BY PULSED ELECTRIC FIELD

The objective of this study was to investigate the effects of pulsed electric field (PEF) treatment on compressing behavior and texture of potatoes. Textural data reveal that PEF treatment can cause enlargement of pressure for the same level of deformation. The fracture pressures P-c were approximately the same for both untreated and PEF-treated specimens, P-c approximate to 4.5 +/- 0.4 MPa. The maximal pressure P-m, at which the time of the pressure-induced rupture of intact cells should be of the same order of magnitude as the time of fluid expression from damaged cells, was estimated as P-m approximate to 6 MPa. For a small pressure (P = 1 MPa) to obtain a similar deformation (epsilon = 0.15) requires pressing time t approximate to 3.5 h for untreated tissue and t approximate to 70 s for PEF-treated tissue. Measured electrical conductivity was practically constant and exhibited no noticeable time dependence during constant pressure stage in untreated samples, while the conductivity of PEF-treated specimens decreases in the course of pressing.