## 3 Results and Discussion
### Colour Measurements  
The appearance of dried quince samples is shown in Figure 1. The obtained results measured in the L*a*b* system, the total colour difference (\(\Delta\)E) and browning index (BI) of _C. oblonga_ flesh, are shown in Table 2. In evaluating the flesh of the quince fruits studied, the value of the L* parameter was statistically significant, the highest in freeze-dried quince \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Characteristics** & **Freeze-Dried** & **Conv-40** & **Conv-60** \\ \hline rehydration ratio & 3.53 \(\pm\) 0.04 a & 2.58 \(\pm\) 0.06 b & 1.84 \(\pm\) 0.04 c \\ \hline shrinkage rate [\%] & 9.87 \(\pm\) 0.29 c & 57.33 \(\pm\) 0.55 b & 66.03 \(\pm\) 0.8 a \\ \hline bulk density [g/cm\({}^{3}\)] & 0.41 \(\pm\) 0.01 c & 0.63 \(\pm\) 0.02 b & 0.71 \(\pm\) 0.02 a \\ \hline \hline \end{tabular}  
* Freeze-Dried—freeze-dried fruit; Conv-40—convection-dried fruit at 40 \({}^{\circ}\)C; Conv-60—convection-dried fruit at 60 \({}^{\circ}\)C; within each line, values with the same letter are not significantly different at \(p<\) 0.05 ([PERSON]’s post hoc test).  
\end{table} 
Table 1: Rehydration ratio, shrinkage rate, and bulk density of dried quince fruits. fruit (79.66 \(\pm\) 1.85), which means that these samples were thebrightest most promising among all those analysed. The lowest L* parameter was observed in convection-dried quince, with no statistically significant differences between drying temperatures of 40 \({}^{\circ}\)C and 60 \({}^{\circ}\)C. This indicates a darker colour compared to fresh and freeze-dried fruit. The values of the a* and b* parameters were highest in quince dried at 60 \({}^{\circ}\)C, followed by 40 \({}^{\circ}\)C. This is related to the approximation of the colour of the fruit flesh to red and yellow. At the same time, these samples also had the highest browning index and total colour difference. Larger values of \(\Delta\)E show more significant changes in colour between fresh and dried fruit. A colour difference of \(\Delta\)E > 5 is interpreted as very pronounced [21]. The literature data report that the colour of vegetables and fruits is influenced by several factors, including storage and transport conditions, during which the degradation of colouring substances (particularly carotenoids and chlorophylls) can occur. In addition, enzymatic and non-enzymatic browning reactions and raw material processing methods (especially heat treatment) significantly affect the colour [22]. The physicochemical properties of the product are also important, such as total acidity, pH, sugar content (especially reducing sugars, which are substrates for the Maillard reaction), polyphenic compound content, and time of exposure to light and atmospheric oxygen [23]. Colour is one of the most essential quality characteristics influencing consumer purchase. Incorrect colour is associated with food deterioration and causes consumers to reject the product [22]. Therefore, this characteristic must be as attractive and similar to the fresh product [21]. Quince is a fruit that turns brown rather quickly after cutting, related to the oxidation of polyphenic compounds and the high activity of the enzyme polyphenol oxidase in the flesh [24]. Therefore, fruit treated with low-pressure sublimation drying is lighter in colour compared to raw and convective-dried fruit. The oxidation of dyes can explain significant colour changes during convection drying due to extended exposure to oxygen and higher drying temperatures. Maillard reactions occur more rapidly at higher  
Figure 1: The general appearance of quince fruits dried by different methods. (**A**)—freeze-dried fruit; (**B**)—convection-dried fruit at 40 \({}^{\circ}\)C; (**C**)—convection-dried fruit at 60 \({}^{\circ}\)C.