## 3 Results and Discussion  
### Color Changes  
The CIELAB color parameters of fresh and dried mango slices are shown in Figure 4. The brightness (\(L^{*}\)) of the samples dried at a low temperature of 40 \({}^{\circ}\)C was well preserved with 67.77 \(\pm\) 4.44 and close to the fresh samples with 68.39 \(\pm\) 2.45. However, the \(L^{*}\) values decreased with increasing drying temperature and a significant (\(p\) < 0.05) difference in \(L^{*}\) values (62.02 \(\pm\) 4.23) was observed when dried at 80 \({}^{\circ}\)C. This could be attributed to the fact that higher drying temperatures are associated with structural deformation of the fruit surface [1; 15] and result in lower \(L^{*}\) values. In addition, it has been documented by many researchers that higher drying temperatures lead to the degradation of the heat-sensitive active compounds inside the fruit [10; 23; 31], which may be associated with a reduction in fruit brightness. A loss of brightness was also reported by Elamin O.M. [13] for conventionally oven-dried mango at 60 \({}^{\circ}\)C to 80 \({}^{\circ}\)C.  
Figure 3: Calibration curve for absorbance versus catalase units per mL. As for the redness parameter, the \(a^{*}\) value of 16.85 \(\pm\) 3.53 increased significantly for mango slices dried at 40 \({}^{\circ}\)C compared to fresh mangoes with 8.92 \(\pm\) 2.30. However, at an increased drying temperature of 60 \({}^{\circ}\)C, the \(a^{*}\) value decreased significantly to 10.09 \(\pm\) 2.29 and approached the fresh samples; while at 80 \({}^{\circ}\)C, they increased again to 12.06 \(\pm\) 2.26. The reason for this phenomenon might be related to the enzymatic and non-enzymatic browning of the fruits [32,33]. A higher \(a^{*}\) value at 40 \({}^{\circ}\)C may be due to the enzymatic browning reactions that normally occur when the enzyme polyphenol oxidase (PPO) comes into contact with the endogenous phenolic compounds during mango drying. Similar findings were also discussed in our previous study [7], where we observed the maximum PPO activity in mango slices dried at 40 \({}^{\circ}\)C. However, drying at 60 \({}^{\circ}\)C and 80 \({}^{\circ}\)C caused the PPO enzyme to deactivate or degrade, resulting in less enzymatic browning reaction. Following that, the higher \(a^{*}\) values at 80 \({}^{\circ}\)C seemed to be a result of brown polymers formed by the Maillard reaction [3,34]. The yellowness (\(b^{*}\)) of the dried mango slices increased significantly after drying, but no significant difference was observed between the different drying temperatures. The increase in \(b^{*}\) values due to drying could be related to the degradation of carotenoids and the formation of brown pigments by non-enzymatic (Maillard reaction) and enzymatic reaction [4,35]. The hue angle (h\({}^{\circ}\)) values are quite useful to express the visual impression of the samples. The lowest \(b^{\circ}\)-values (73.43 \(\pm\) 4.18) were obtained for mango slices dried at 40 \({}^{\circ}\)C compared to fresh samples (80.09 \(\pm\) 2.69), and those dried at 60 \({}^{\circ}\)C (80.14 \(\pm\) 2.34) and 80 \({}^{\circ}\)C (78.34 \(\pm\) 2.40). This directly reflects the higher \(a^{*}\) value at 40 \({}^{\circ}\)C, as previously discussed, because there was no significant difference in \(b^{*}\) values at different drying temperatures. In general, color is one of the most important sensory attributes of dried fruits that has a direct impact on quality perception and consumer acceptance [9,36]. However, considering color as a quality parameter to assess the quality of dried fruits is a rather fallacious decision, especially when preferences are mainly focused on the nutritional value of the dried fruits. For instance, as discussed in our results, no significant difference was  
Figure 4: Color values: (\(L^{*}\)) lightness, (\(a^{*}\)) green-red, and (\(b^{*}\)) blue-yellow as well as (\(l^{\circ}\)) hue angle of fresh and dried mango slices.