## 2 Results and Discussion
### Color Analysis
\begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Drying Conditions**} & \multicolumn{3}{c}{**Color Parameters**} \\ \cline{2-4}  & \(L^{*}\) & \(a^{*}\) & \(b^{*}\) \\ \hline Fresh & \(46.90\pm 0.09\)\({}^{\circ}\) & \(-6.33\pm 0.09\)\({}^{\circ}\) & \(18.52\pm 0.12\)\({}^{\mathrm{a}}\) \\ CD 40 \({}^{\circ}\)C & \(45.23\pm 0.24\)\({}^{\mathrm{a,b,c}}\) & \(-6.35\pm 0.07\)\({}^{\mathrm{a}}\) & \(15.92\pm 0.09\)\({}^{\mathrm{b}}\) \\ CD 50 \({}^{\circ}\)C & \(46.56\pm 0.13\)\({}^{\circ}\) & \(-5.5\pm 0.04\)\({}^{\mathrm{b,c}}\) & \(16.05\pm 0.13\)\({}^{\mathrm{b}}\) \\ CD 60 \({}^{\circ}\)C & \(46.05\pm 0.08\)\({}^{\mathrm{b,c}}\) & \(-5.21\pm 0.03\)\({}^{\mathrm{c}}\) & \(15.86\pm 0.06\)\({}^{\mathrm{b}}\) \\ VMD 6 W/g & \(45.62\pm 0.16\)\({}^{\mathrm{a,b,c}}\) & \(-5.96\pm 0.19\)\({}^{\mathrm{a,b}}\) & \(17.17\pm 0.30\)\({}^{\mathrm{d}}\) \\ VMD 9 W/g & \(44.54\pm 0.04\)\({}^{\mathrm{a,b}}\) & \(-5.5\pm 0.04\)\({}^{\mathrm{b,c}}\) & \(16.14\pm 0.05\)\({}^{\mathrm{b}}\) \\ VMD 12 W/g & \(43.94\pm 0.22\)\({}^{\mathrm{a}}\) & \(-5.86\pm 0.05\)\({}^{\mathrm{b}}\) & \(16.31\pm 0.06\)\({}^{\mathrm{b,c}}\) \\ CPD–VMFD & \(46.49\pm 0.16\)\({}^{\mathrm{c}}\) & \(-7.02\pm 0.02\)\({}^{\mathrm{d}}\) & \(16.77\pm 0.15\)\({}^{\mathrm{c,d}}\) \\ \hline \hline \end{tabular} CD—convective drying: VMD—vacuum microwave drying: CPD—convective pre-drying: VMFD—vacuum microwave finish drying: mean values with different alphabets (a, b, c, d) within each column is significantly different (\(p<0.05\)), according to [PERSON]’s test.  
\end{table} 
Table 6: Color parameters of _P. nodiflora_ leaves measured after applications of different drying methods. \begin{table}
\begin{tabular}{c c} \hline \hline \multicolumn{1}{c}{**Drying Method**} & **Water Activity, \(\mathrm{a_{w}}\)** \\ \hline Fresh & \(0.9879\pm 0.006\)\({}^{\mathrm{a}}\) \\ CD 40 \({}^{\circ}\)C & \(0.2252\pm 0.003\)\({}^{\mathrm{b,d}}\) \\ CD 50 \({}^{\circ}\)C & \(0.1485\pm 0.010\)\({}^{\mathrm{c}}\) \\ CD 60 \({}^{\circ}\)C & \(0.1081\pm 0.010\)\({}^{\mathrm{c}}\) \\ VMD 6 W/g & \(0.2780\pm 0.001\)\({}^{\mathrm{d}}\) \\ VMD 9 W/g & \(0.1743\pm 0.044\)\({}^{\mathrm{b,c}}\) \\ VMD 12 W/g & \(0.2353\pm 0.008\)\({}^{\mathrm{b,d}}\) \\ CPD–VMFD & \(0.1339\pm 0.020\)\({}^{\mathrm{c}}\) \\ \hline \hline \end{tabular} CD—convective drying: VMD—vacuum microwave drying: CPD—convective pre-drying: VMFD—vacuum microwave finish drying: mean values with different alphabets (a, b, c, d) within each column is significantly different (\(p<0.05\)), according to [PERSON]’s test.  
\end{table} 
Table 7: Water activity of different drying methods. Carotenoids, which tend to have yellowish color, were far better preserved in VMD 6 W/g, as indicated by a higher \(b^{\star}\) value. High vacuum conditions and lower temperatures of VMD compared with CD methods guaranteed improved preservation of carotenoids. In the presence of oxygen, the susceptibility of carotenoids to oxidation is high [51]; therefore, we can assume that higher oxidation occurred during CD. However, shortening drying time of CD by applying vacuum microwaves increased the value of \(b^{\star}\) coordinate, thereby indicating the effectiveness of CPD-VMFD in preserving natural colorants.