## 3 Results and Discussion
### UV Irradiation of Mushroom Powders  
The primary objective was to optimize UV irradiation conditions to enhance the vitamin D\({}_{2}\) and ergosterol content of mushroom powders, with the aim of developing an efficient technology for producing mushroom-based dietary supplements. It is well-established that UV irradiation facilitates the conversion of ergosterol to previtamin D\({}_{2}\), which is subsequently transformed into ergocalciferol (vitamin D\({}_{2}\)) [10; 12]. Additionally, it has been shown that heat treatment increases the conversion of previtamin D\({}_{2}\) to vitamin D\({}_{2}\)[6]. In the experiments, UV irradiation was combined with heat treatment to achieve higher vitamin D\({}_{2}\) concentrations in mushroom powders. Mushroom powders, dried at room temperature, were subjected to heat treatment at 100 \({}^{\circ}\)C, followed by UV irradiation. The results for white button and shitake mushrooms are summarized in Tables 2 and 3, respectively. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Sample 1** & \multicolumn{2}{c}{**White Button**} & \multicolumn{2}{c}{**Shitake**} \\ \hline  & **Vitamin D\({}_{2}\)** & **Ergosterol** & **Vitamin D\({}_{2}\)** & **Ergosterol** \\  & **(mg/ kg dry weight)** & **(mg/ kg dry weight)** & **(mg/ kg dry weight)** & **(mg/ kg dry weight)** \\ \hline
1 & 2.40 \(\pm\) 0.17 & 1451.00 \(\pm\) 24.36 & 8.33 \(\pm\) 0.24 & 2445.20 \(\pm\) 38.67 \\
2 & 2.62 \(\pm\) 0.22 & 1522.00 \(\pm\) 30.20 & 7.52 \(\pm\) 0.19 & 2015.80 \(\pm\) 30.58 \\
3 & 1.92 \(\pm\) 0.16 & 1723.30 \(\pm\) 40.08 & 7.11 \(\pm\) 0.13 & 1921.30 \(\pm\) 52.17 \\ \hline \hline \end{tabular}  
* Each mushroom sample was prepared and measured in five parallel measurements, with each measurement injected three times. Mean values are presented with standard deviations.  
\end{table} 
Table 1: Average values of vitamin D\({}_{2}\) and ergosterol content in cultivated mushroom samples analyzed by HPLC-DAD. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Time of Heat** & **UV Irradiation After Heat** & **Vitamin D\({}_{2}\) (mg/kg** & **Ergosterol (mg/kg** \\
**Treatment (h)** & **Treatment (10 g, 10 min)** & **Dry Weight)** & **Dry Weight)** \\ \hline
0 & \(-\) & 1.92 \(\pm\) 0.16 a  & 1723.3 \(\pm\) 40.08 a  \\
0 & \(+\) & 11.77 \(\pm\) 0.41 d  & 1782.3 \(\pm\) 51.98 a  \\
1 & \(-\) & 2.13 \(\pm\) 0.22 a  & 1809.00 \(\pm\) 57.61 a  \\
1 & \(+\) & 12.51 \(\pm\) 0.44 d  \\
2 & \(-\) & 2.45 \(\pm\) 0.28 a  & 1865.00 \(\pm\) 48.07 b  \\
2 & \(+\) & 14.68 \(\pm\) 0.50 e  & 1767.67 \(\pm\) 50.80 a  \\
5 & \(-\) & 3.20 \(\pm\) 0.37 b  \\
5 & \(+\) & 19.39 \(\pm\) 0.74 f  & 1574.67 \(\pm\) 60.75 d  \\
10 & \(-\) & 4.66 \(\pm\) 0.37 c  & 1708.33 \(\pm\) 53.14 c  \\
10 & \(+\) & 28.13 \(\pm\) 0.78 s  \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Effect of heat treatment and UV irradiation on vitamin D\({}_{2}\) and ergosterol content in white button mushroom powder. For _A. bisporus_, heat treatment alone resulted in a gradual increase in vitamin D\({}_{2}\) content, reaching 4.66 mg/kg from an initial 1.92 mg/kg after 10 h at 100 \({}^{\circ}\)C. Both 5 and 10 h long heat treatments resulted in significant enhancement in vitamin D\({}_{2}\) content. When heat treatment was followed by UV irradiation, a substantial further increase in vitamin D\({}_{2}\) levels was observed, with the highest concentration recorded (28.13 mg/kg) after 10 h of heating followed by UV exposure. In the case of white button mushrooms, the combination of 10 h heat treatment and UV irradiation resulted in the highest vitamin D\({}_{2}\) concentration, but a significant decrease in ergosterol concentration was also observed. In contrast, _L. edodes_ exhibited different responses. Heat treatment led to a similar gradual increase in vitamin D\({}_{2}\) levels but after 2 h, further heat treatment did not lead to significant enhancement. Subsequent UV irradiation resulted in a comparatively smaller increase in contrast to _A. bisporus_.