## 3 Results and Discussion
### Multi-Objective Optimization
The ID92 is characterized by EC = 434.8 MJ/kg (1.6 times higher than EC\({}_{\text{min}}\)), whereas A\({}_{\text{loss}}\) = 39.0 (the lowest of all obtained optimization solutions), TAC\({}_{\text{loss}}\) = 36.8% (2.4 times higher than TACloss min), TFC\({}_{\text{loss}}\) = 9.4% (1.4 times higher than TEC\({}_{\text{loss}}\) min), and TPC\({}_{\text{loss}}\) is 37.0% (1.4 times higher than TPC\({}_{\text{loss}}\) min) (CD = 38.3--2.2 times higher than CD\({}_{\text{min}}\)). The parameters of the drying process for ID92 are the following: \(T_{d}\) = 53.94 \({}^{\circ}\)C and \(v_{d}\) = 1.00 m/s. The ID109 solution differs only in value of \(T_{d}\) (\(T_{d}\) is 0.57 \({}^{\circ}\)C higher than for ID92 and amounts to 54.51 \({}^{\circ}\)C (\(v_{d}\) = 1.00 m/s). For this solution, EC is a little lower (420 MJ/kg), but TAC\({}_{\text{loss}}\) is higher (40.1%). The next ID107 solution (EC = 410.1 MJ/kg) is characterized by the lowest of the four solutions TPC\({}_{\text{loss}}\) = 26.0% (1.2 times higher than TPC\({}_{\text{loss}}\) min). For this solution, TAC\({}_{\text{loss}}\) is higher than for the previously mentioned ID92 and lower than ID109 (TAC\({}_{\text{loss}}\) = 39.2%-2.5 times higher than TAC\({}_{\text{loss}}\) min), but TEC\({}_{\text{loss}}\) and A\({}_{\text{loss}}\) are already much bigger: TFC\({}_{\text{loss}}\) = 29.6% (4.3 times higher than TEC\({}_{\text{loss}}\) min), and A\({}_{\text{loss}}\) = 48.7% (1.3 times higher than A\({}_{\text{loss}}\) min), CD is high and amount 37%. The parameters of the drying process for ID107 are the following: \(T_{d}\) = 59.82 \({}^{\circ}\)C and \(v_{d}\) = 0.53 m/s. A similar solution is ID111 for which EC, TFC\({}_{\text{loss}}\), A\({}_{\text{loss}}\) are lower and amount to 381.3 MJ/kg, 29.1%, 48.12%, while TAC\({}_{\text{loss}}\) and TPC\({}_{\text{loss}}\) are larger (41.2% and 27.0%, respectively); CD is high: 36.9%. The parameters of the drying process for ID111 are very similar to ID107 and amount: \(T_{d}\) = 59.85 \({}^{\circ}\)C and \(v_{d}\) = 0.52 m/s. For this solution, EC is little lower (381.3 MJ/kg), but TAC\({}_{\text{loss}}\) and TPC\({}_{\text{loss}}\) are higher (41.2 and 27.0%, respectively). Figure 6 shows Pareto fronts for EC and, simultaneously, A\({}_{\text{loss}}\), TAC\({}_{\text{loss}}\), TEC\({}_{\text{loss}}\), and TPC\({}_{\text{loss}}\). Considering the maximum values of TAC\({}_{\text{loss}}\) max = 80.5%, TFC\({}_{\text{loss}}\) max = 70.9%, A\({}_{\text{loss}}\) max = 76.9%, and TPC\({}_{\text{loss}}\) max = 60.6%, it can be assumed that for the four indicated solutions, the losses do not differ significantly and are much smaller than the mentioned maximum losses. However, where the quality of the dried product directly affects the price (poor-quality product is worthless), the drying process should be carried out with the acceptable (not always the lowest) energy expenditure. For the strategy in which, apart from EC minimization, the lower losses of TAC, TFC and A are most important, while accepting quite high TPC\({}_{\text{loss}}\) and high CD, the drying parameters of _E. anoneum_ petals are the following: \(T_{d}\) = 54.0 \({}^{\circ}\)C and \(v_{d}\) = 1.0 m/s. Assuming the mentioned accuracy of \(T_{d}\) and \(v_{d}\) setting, drying at \(T_{d}=54.0\pm 0.5\)\({}^{\circ}\)C and \(v_{d}=1.0\pm 0.02\) m/s can obtain _Echium amoenum_ petals with the following parameters: TAC\({}_{\text{loss}}\), TFC\({}_{\text{loss}}\), A\({}_{\text{loss}}\), TPC\({}_{\text{loss}}\), CD, EC: 36.8%, 9.4%, 39.0%, 38.3%, 37.1, and 434.9 MJ/kg, respectively (average values for mentioned ranges of \(T_{d}\) and \(v_{d}\)). However, when apart from EC minimization, low losses of TPC and TFC are important; with losses of TAC and CD similar to those mentioned previously, the drying parameters of _E. amoenum_ petals are the following: \(T_{d}=59.8\)\({}^{\circ}\)C and \(v_{d}=0.53\) m/s.