## 3 Results and Discussion  
### Quantitative and Qualitative Characteristics  
Table 1 shows the rehydration, shrinkage, and bulk density values obtained for freeze-dried and convection-dried quince fruits at 40 \({}^{\circ}\)C and 60 \({}^{\circ}\)C. Rehydration is a complex process of reabsorption of water by a material after it has already been removed. However, lost water cannot be restored to its original state. Many factors, including processing conditions and product properties, among them the characteristics of the pore network, affect the rehydration process [19]. This study found that the rehydration coefficient of convection-dried quince was significantly lower than the freeze-dried sample. Quince fruits dried at 60 \({}^{\circ}\)C had a lower rehydration coefficient (1.84 \(\pm\) 0.04) compared to samples dried at 40 \({}^{\circ}\)C (2.58 \(\pm\) 0.06). [PERSON] and [PERSON] [20] noted a similar correlation, reporting a significantly lower rehydration rate for convection-dried quince cubes compared to freeze-dried, as well as [PERSON] and [PERSON] [5] for drying pumpkin slices. [PERSON] et al. [10] also noted a significantly lower rehydration rate of convection-dried apricot slices at 60 \({}^{\circ}\)C compared to sublimation-dried samples. This may be due to the formation of a \"shell\" on the surface of the dried fruit and the collapse of the inner cell matrix due to high temperatures, which in turn affects the penetration of external water into the slices [10]. Convection drying disrupts the structure of food cells due to high shrinkage levels. This shrinkage reduces the hydrophobicity of the sample [20]. Product shrinkage is a common physical occurrence during crop drying. The action of heat causes stresses in the cellular structure of the product, leading to shrinkage and deformation. Food shrinkage during drying reduces rehydration capacity and bulk density [11]. In this study, convection-dried fruit had the highest shrinkage percentage, at 66.03 \(\pm\) 0.8 for quince dried at 60 \({}^{\circ}\)C and 57.33 \(\pm\) 0.55 for fruit dried at 40 \({}^{\circ}\)C, respectively. The freeze-dried sample had the lowest percentage of shrinkage (9.87 \(\pm\) 0.29%), indicating that its volume remained nearly unchanged during the water removal process. According to the literature, ice sublimation leaves an extensive pore network, so the material has slight shrinkage. [PERSON] et al. [10] obtained similar results by comparing different methods of drying apricot slices, finding the lowest percentage of shrinkage for freeze-dried samples and the highest for hot air-dried samples. In the study presented here, freeze-dried samples had the lowest values of bulk density (0.41 \(\pm\) 0.01 g/cm\({}^{3}\)), since freeze drying allows for ice sublimation, leaving voids in the structure without significant shrinkage. Samples dried at 40 \({}^{\circ}\)C (0.63 \(\pm\) 0.02) and 60 \({}^{\circ}\)C (0.71 \(\pm\) 0.02) had significantly higher bulk density values. Bulk density depends on the shrinkage rate, which strongly depends on the chosen drying method [4]. Bulk density testing is significant in food product packaging, storage and transportation [11].