## 3 Results and Discussion  
### Amylase Activity in Fresh and dried Samples  
Figure 1 shows the amylase activity in fresh and dried samples of the varieties Sindri, SB Chaunsa, and Tommy Atkins. For the fresh samples, SB Chaunsa displayed the highest activity (4.08-4.66 units min\({}^{-1}\) g\({}^{-1}\)), followed by Tommy Atkins (2.10-2.95 units min\({}^{-1}\) g\({}^{-1}\)), whereas Sindri revealed the lowest activity (1.09-2.15 units min\({}^{-1}\) g\({}^{-1}\)). This finding may be due to the differences in varieties, climatic origin, and compositional varia  
tions. Similar results were also observed in previous studies for fresh mango by [PERSON] et al. [3] and [PERSON] et al. [33]. However, after hot-air convective drying, the amylase activity of the dried samples was distinctly influenced by the drying temperature and air velocity. At drying temperatures from 40 \({}^{\circ}\)C to 80 \({}^{\circ}\)C and an air velocity of 1.0 m s\({}^{-1}\), the highest amylase activity (4.67 \(\pm\) 0.49, 4.30 \(\pm\) 0.46, and 7.22 \(\pm\) 0.73 units min\({}^{-1}\) g\({}^{-1}\), respectively) in all three varieties was preserved in samples dried at 80 \({}^{\circ}\)C, and the lowest (3.33 \(\pm\) 0.14, 3.07 \(\pm\) 0.37, and 4.93 \(\pm\) 0.94 units min\({}^{-1}\) g\({}^{-1}\), respectively) was observed in samples dried at 40 \({}^{\circ}\)C. This could be delineated by the fact that drying at 80 \({}^{\circ}\)C required a shorter drying time (277 \(\pm\) 35 min) than drying at 40 \({}^{\circ}\)C (965 \(\pm\) 171 min) [2]. As amylase is a heat-resistant enzyme, a decrease in drying time has a positive effect on the activity retention of amylase in dried samples. It is also generally known that the thermal stability of heat-resistant enzymes is markedly enhanced as a result of water evaporation [34; 35]. This means that rapid water evaporation at higher drying temperatures contributes to a better preservation of enzyme activity. However, the elevated drying temperature must not be greater than the resistance limit. Alternatively, prolonged drying time at low temperature is associated with the degradation of amylase, which may be attributed to many different reasons that include the longer exposure to heat or oxidation, low water evaporation rate, product accumulation, unavailability of the substrate, and other physicochemical alterations. The related results were also reported by [PERSON] et al. [36] that extending drying times and high moisture content enhanced amylase degradation during drying of commercial fungal alpha-amylase.  
Furthermore, the results also revealed that an increase in air velocity from 1.0 m s\({}^{-1}\) to 1.4 m s\({}^{-1}\) at drying temperatures of 40 \({}^{\circ}\)C to 80 \({}^{\circ}\)C had a beneficial effect on the activity retention of amylase in dried mango of all three varieties, and helped to preserve  
Figure 1: Amylase activity in fresh and dried mango of the varieties Sindri, SB Chaunsa, and Tommy Atkins; D = dried samples at temperatures 40 \({}^{\circ}\)C to 80 \({}^{\circ}\)C. a–g, different letters in the box plot indicate significant differences \(p\) < 0.05, (\(n\) = 20 \(\times\) 3).  
4.81-42.50% more amylase units in the final product. This behavior might be attributed to the fact that at the same drying temperature higher air velocity results in a significant reduction in drying time [2; 15]. Thus, a decreased drying time has positively influenced the decrease in the thermal degradation of amylase. Therefore, at the same drying temperature, the samples dried at the higher air velocity of 1.4 m s\({}^{-1}\) retained a higher amylase activity.