# Effect of Tomato Juice and Different Drying Methods on Selected Properties of Courgette
## 3 Results and Discussion
### Color  
The detailed appearance is shown in Figure 6. The highest brightness value (L*) was observed for courgettes after freeze drying (83.4). This indicates an increase in the value of the studied parameter compared to the raw material (Table 1). An increase in brightness in the freeze-dried courgette was also observed by other authors studying pear pomace [33] and Gastrodia elata [34]. Freeze drying is the only one to show an increase in brightness in both the courgette without pretreatment and the courgette after the vacuum impregnation process. In addition, it was observed that courgettes after convection drying at 50 \({}^{\circ}\)C showed significant darkening, which was noted as the lowest values of the L* parameter  
Figure 5: Drying shrinkage of courgette (C) and courgette after vacuum impregnation (CT), freeze-dried (FD), vacuum-dried (VD), and convection-dried at 50 \({}^{\circ}\)C (CD50), 60 \({}^{\circ}\)C (CD60), and 70 \({}^{\circ}\)C (CD70). and the largest color differences \(\Delta\)E. Typically, the greatest change in color is associated with drying under the influence of warm air [35], which is confirmed by studies performed by other authors [10,33]. In all the samples studied, it was observed that the addition of tomato juice reduced the value of the color parameter L*; this is due to the darker color of the impregnating solution used. These results are in accordance with previously performed studies [14,33]. Referring to the effect of the impregnation process using tomato juice on the color of the courgette, attention was drawn to the increased values of the parameter (a*), particularly evident in the courgette samples after convection drying at 50 \({}^{\circ}\)C. Positive values indicate an increase in the intensity of red in the color of the product, which is directly related to the use of tomato juice as an impregnating solution. Such an increase can have a significant impact on the sensory perception of courgettes by potential consumers, underscoring the importance of selecting appropriate juices in the impregnation process to achieve the desired color characteristics. In addition, when considering the effect of the temperature of the drying medium during convection drying on the color parameters studied, it was observed that a higher drying temperature did not unequivocally reduce the brightness of the courgette, suggesting that other factors, such as drying time or the characteristics of the courgette itself, may play an equally important role. In dries obtained using the convection method, the greatest \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Method** & **L*** & **a*** & **b*** & **\(\Delta\)E** \\ \hline C & 80.16 \(\pm\) 1.10 d & \(-\)5.67 \(\pm\) 0.36 a & 17.90 \(\pm\) 0.40 a & - \\ C FD & 83.40 \(\pm\) 1.02 d & \(-\)2.63 \(\pm\) 0.45 b & 19.43 \(\pm\) 0.23 b & 4.70 \\ C VD & 80.59 \(\pm\) 0.57 d & \(-\)5.29 \(\pm\) 0.33 a & 19.13 \(\pm\) 0.51 b & 1.35 \\ C CD50 & 73.37 \(\pm\) 0.29 c & \(-\)3.36 \(\pm\) 0.45 b & 21.25 \(\pm\) 1.01 c & 7.92 \\ C CD60 & 80.76 \(\pm\) 1.94 d & \(-\)4.44 \(\pm\) 0.38 a & 19.76 \(\pm\) 0.97 b & 2.31 \\ C CD70 & 78.25 \(\pm\) 0.96 c & \(-\)4.67 \(\pm\) 0.44 a & 20.15 \(\pm\) 1.06 c & 3.11 \\ CT & 58.00 \(\pm\) 1.91 b & 0.45 \(\pm\) 0.18 b & 19.12 \(\pm\) 0.50 b & 23.02 \\ CT FD & 77.62 \(\pm\) 1.74 c & 1.59 \(\pm\) 0.45 c & 23.40 \(\pm\) 0.32 e & 9.45 \\ CT VD & 59.50 \(\pm\) 0.57 b & 2.65 \(\pm\) 0.24 c & 21.82 \(\pm\) 0.46 c & 22.62 \\ CT CD50 & 45.01 \(\pm\) 1.68 a & 8.44 \(\pm\) 0.99 f & 17.48 \(\pm\) 0.69 a & 37.88 \\ CT CD60 & 57.27 \(\pm\) 0.57 b & 4.31 \(\pm\) 0.31 d & 22.63 \(\pm\) 0.22 d & 25.42 \\ CT CD70 & 56.32 \(\pm\) 0.72 b & 6.59 \(\pm\) 0.38 e & 22.20 \(\pm\) 0.44 d & 27.15 \\ \hline \hline \end{tabular} Values (mean of three replications) \(\pm\) standard deviation followed by different letters (a–f) are different (\(p\leq 0.05\)) according to [PERSON]’s test.  
\end{table} 
Table 1: Color of courgettes without pretreatment (C) and after pretreatment (CT), freeze-dried (FD), vacuum-dried (VD), and convection-dried (CD).