## 4 Conclusions  
The effects of heat treatment and UV irradiation on the concentrations of vitamin D\({}_{2}\) and ergosterol in mushroom powders were investigated in this study. Considering the practical feasibility of industrial applications, a 10 min UV treatment and a heating temperature of 100 \({}^{\circ}\)C were identified as optimal conditions to balance efficiency, cost-effectiveness, and product integrity. These parameters ensure a viable enrichment process without excessive energy consumption or unfavorable degradation effects. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Time of Heat** & \begin{tabular}{c} **UV Irradiation After Heat** \\ **Treatment** \\ **(10 g, 10 min)** \\ \end{tabular} & \
\begin{tabular}{c} **Vitamin D\({}_{2}\)** \\ **(mg/kg Dry Weight)** \\ \end{tabular} &
\begin{tabular}{c} **Ergosterol (mg/kg** \\ **Dry Weight)** \\ \end{tabular} \\ \hline
0 & \(-\) & 7.11 \(\pm\) 0.13  & 1921.30 \(\pm\) 52.17  \\
0 & \(+\) & 28.61 \(\pm\) 0.80  & 1731.30 \(\pm\) 41.02 f \\
1 & \(-\) & 7.28 \(\pm\) 0.29  & 1671.67 \(\pm\) 43.98  \\
1 & \(+\) & 14.26 \(\pm\) 0.28  & 1540.33 \(\pm\) 34.95  \\
2 & \(-\) & 7.86 \(\pm\) 0.32  & 1366.00 \(\pm\) 30.64  \\
2 & \(+\) & 9.82 \(\pm\) 0.34  & 1339.67 \(\pm\) 38.59  \\
5 & \(-\) & 8.35 \(\pm\) 0.46  & 1145.00 \(\pm\) 28.16  \\
5 & \(+\) & 8.56 \(\pm\) 0.38  & 1117.67 \(\pm\) 27.06  \\
10 & \(-\) & 8.46 \(\pm\) 0.39  & 1037.33 \(\pm\) 25.89  \\
10 & \(+\) & 8.52 \(\pm\) 0.31  & 994.33 \(\pm\) 27.54  \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Effect of heat treatment and UV irradiation on vitamin D\({}_{2}\) and ergosterol content in shitake mushroom powder. The results demonstrated that combining these treatments significantly enhances vitamin D\({}_{2}\) levels, particularly in _Agaricus bisporus_. Heat treatment alone increased vitamin D\({}_{2}\) content from 1.92 mg/kg to 4.66 mg/kg after 10 h at 100 \({}^{\circ}\)C, while the combination of heat and UV treatment resulted in a 14-fold increase, reaching 28.13 mg/kg. In contrast, _Lentinula edodes_ exhibited a different response, where UV treatment alone led to the highest vitamin D\({}_{2}\) levels (28.61 mg/kg) while better preserving ergosterol content. This highlights species-specific differences in vitamin D\({}_{2}\) conversion and suggests that optimal processing conditions should be tailored accordingly. Additionally, a straightforward HPLC-DAD method was developed for the simultaneous analysis of vitamin D\({}_{2}\) and ergosterol. The method demonstrated high recovery rates (97-99%), a limit of detection (LOD) of 0.1 mg/kg dry weight, and a limit of quantitation (LOQ) of 0.5 mg/kg dry weight, confirming its robustness and precision. The observed ergosterol degradation in _A. bisporus_ after prolonged heat and UV exposure suggests that excessive processing may reduce sterol availability, potentially affecting the overall nutritional quality of the product. In contrast, _L. edodes_ retained higher ergosterol levels when subjected to UV treatment alone, making it a preferable approach for preserving both vitamin D\({}_{2}\) and sterol content in this mushroom. These findings provide valuable insights for optimizing vitamin D\({}_{2}\) enrichment strategies in mushroom-based food products. The combined application of heat and UV treatment offers a scalable and efficient approach for industrial vitamin D\({}_{2}\) fortification, particularly for _A. bisporus_, while _L. edodes_ may benefit more from UV-only treatment. However, further research should explore long-term stability, bioavailability, and consumer acceptability to ensure the effectiveness of these treatments in commercial applications. Conceptualization, J.B., C.C., M.V. and C.V.; methodology, J.B., A.M. and M.V. ; validation, J.R. and C.C. ; formal analysis, J.B. and C.C. ; investigation, J.B. and A.M.; resources, J.B., J.R., C.C., M.V. and C.V.; data curation, J.B., A.M. and C.C. ; writing--original draft preparation, J.B., M.V., C.V. and C.C. ; writing--review and editing, J.B., C.C., M.V.