## 3 Results
### Osmotic Dehydration of PEF Pre-Treated Tomatoes  
#### 3.2.1 Water Loss and Solids Gain of PEF Pre-Treated Tomatoes during OD  
PEF pre-treatment had a significant (\(p<0.05\)) effect on both water loss (_WL_) and solids gain (\(SG\)) during osmotic dehydration. Dehydration curves in terms of _WL_ and \(SG\) for untreated and PEF treated samples are presented in Figure 2. Regarding untreated cut tomato morsels, _WL_ and \(SG\) reached values up to 4.4 and 1.6 g/g DW, respectively. These results are in agreement with [PERSON] et al. [18], who reported a range of _WL_ and \(SG\) during OD (60% glycerol, 35 \({}^{\circ}\)C) of tomato slices up to 9 and 3 g/g DW, respectively. The difference between the values reported in the literature may be due to the different geometric characteristics of the tomato samples. The diffusion from cut tomato morsels takes place only from one side (the area where the cherry tomato was cut). For tomato slices, the diffusion takes place from both sides, a fact that justifies that _WL_ and \(SG\) for these samples were twice as high. Increasing PEF processing intensity up to 100 pulses led to an increase in _WL_ and \(SG\). However, a further increase in applied pulses did not lead to further acceleration of dehydration.  
Fitting [PERSON]'s law to the experimental data enabled the calculation of the effective diffusion coefficients (\(D_{\mathit{eff}}\)) for both moisture and solids (Table 1). The effective moisture diffusion coefficient exhibited a significant increase of up to 53% for _WL_ and 20% for \(SG\) by applying PEF treatment of 100 pulses. This observation corresponds to an accelerated dehydration caused by the varying degrees of electroporation achieved. Calculated _DEI_ values also indicated that _WL_ was higher than \(SG\), and enhanced by the electroporation achieved (from 20-50 to 300 pulses) (Table 1). [PERSON] et al. [17] reported similar results for OD (30% glycerol, 35 \({}^{\circ}\)C) of untreated and PEF-treated kiwifruit disks. Specifically, PEF treatment of kiwifruit at 1.8 kV/cm for 250 pulses increased \(D_{\mathit{eff}}\) for moisture and solids by 120% and 46%, respectively. In another work, [PERSON] et al. [18] reported that PEF pre-treatment of goji berry (2.8 kV/cm, 750 pulses) significantly increased \(D_{\mathit{eff}}\) for _WL_ from 0.28 \(\times\) 10\({}^{-9}\) to 1.81 \(\times\) 10\({}^{-9}\) m\({}^{2}\)/s and for \(SG\) from 0.95 \(\times\) 10\({}^{-9}\) to 1.81 \(\times\) 10\({}^{-9}\) m\({}^{2}\)/s after OD with 60% glycerol at 55 \({}^{\circ}\)C. Increasing the applied pulses from 100 to 300 did not further increase the moisture diffusion coefficient, signifying that the maximum obtainable degree of electroporation at an electric field of 1.8 kV/cm has been already attained. This observation is also consistent with the results pertaining to tissue softening (decrease of firmness).  
Figure 2: Evolution of (**a**) water loss (_WL_) and (**b**) solids gain (\(SG\)) during osmotic dehydration of untreated (Control) and PEF-treated samples, at 1.8 kV/cm with 20, 50, 100 and 300 pulses (average values \(\pm\) standard deviations). Solid lines represent the fitting of [PERSON]’s law to the experimental data.