Texture of fried potato tissue as affected by pre-blanching in some salt solutions

Planar potato crisps were prepared from potato tubers of four varieties (Agria, Javor, Nicola and Panda). The effect of slice blanching in water and solutions of Na-, Ca-, and Mg-chlorides prior to frying, as well as the effect of storage time of the tubers prior to test were also studied. The deformation curves from a three point Bending test were evaluated and Young's modulus (EM), maximum relative deflection (MRD), maximum tensile stress (MTS) and surface energy (SE) were determined. The MRD and MTS correspond to rupture point values of deflection and stress, respectively. The obtained results show that almost all test parameters (MTS is an exception) depend mainly on the blanching solution and the ratio of monovalent (K and Na) to divalent ions (Ca and Mg) in the crisps. Variety dependence was observed mainly in MRD and EM. An increase in the ratio monovalent over divalent cation concentrations led to lower MRD- and SE-values: and at the same conditions to higher Young's moduli. EM-values of 320-340 MPa were obtained for the two varieties with higher content of starch (Javor and Panda) while for the two varieties with lower starch content (Agria and Nicola) values of 230-250 MPa were observed. The MRD was of 0.057-0.061 for Javor and Panda and 0.075-0.080 for Agria and Nicola. The starch content could not explain the observed variety differences for maximum tensile stress and surface energy.