## 3 Results and Discussion
### Evaluation of Oxidative Stress Markers and Antioxidant Content in Melatonin-Treated Dried Apricots
However, the non-linear relationship between melatonin concentration and \(\beta\)-carotene content warrants further investigation as it may indicate complex interactions between antioxidant systems in response to exogenous melatonin application. The observed increase in \(\beta\)-carotene content at 100 uM melatonin, followed by a decrease at 1000 uM, suggests the existence of an optimal concentration for preserving this important antioxidant compound. The observed variations in biochemical parameters across treatments highlight the concentration-dependent effects of melatonin. The 100 uM melatonin application emerged as particularly effective in reducing oxidative stress markers while enhancing \(\beta\)-carotene retention. These findings align with the growing body of evidence supporting melatonin's role in modulating fruit physiology and quality attributes during post-harvest processing [37; 38]. While our results demonstrate promising outcomes with melatonin treatment, it is crucial to acknowledge the nuanced statistical variations across different concentrations. Although we observed beneficial trends with the 100 uM melatonin application, many parameters showed no statistically significant differences between the 100 uM and 1000 uM treatments. These parameters include color measurements, MDA, H\({}_{2}\)O\({}_{2}\), glucose, fructose, sucrose, total phenolic content (TPC), and antioxidant capacity assessed by DPPH and CUPRAC methods. This observation underscores the importance of careful interpretation and suggests that the optimal melatonin concentration may not always correlate linearly with improved fruit characteristics. The 100 uM concentration was highlighted as particularly effective primarily due to its statistically significant differences from the control and low-dose (10 uM) groups in key parameters such as MDA levels and \(\beta\)-carotene content. However, the lack of significant differences between 100 uM and 1000 uM treatments indicates potentially diminishing returns at higher melatonin concentrations. This finding emphasizes the need for precise dosage optimization in post-harvest fruit treatments and suggests that future studies should focus on more granular concentration ranges to elucidate the most effective melatonin application strategy. \begin{table}
\begin{tabular}{l c c c c} \hline \hline \multirow{2}{*}{**Treatments**} & **MDA** & **H\({}_{2}\)O\({}_{2}\)** & **Melatonin** & \(\beta\)**-Carotene** \\  & **μmol/L** & **μmol/g** & **ng/mL** & **mg/kg** \\ \hline Control & 23.44 \(\pm\) 3.03 a & 1.03 \(\pm\) 0.11 a & Nd & 181.84 \(\pm\) 2.11 b \\
10 uM-MT & 22.75 \(\pm\) 5.33 ab & 1.00 \(\pm\) 0.13 a & Nd & 190.57 \(\pm\) 8.31 ab \\
100 uM-MT & 16.55 \(\pm\) 3.45 b & 0.76 \(\pm\) 0.07 b & Nd & 223.07 \(\pm\) 32.05 a \\
1000 μM-MT & 18.50 \(\pm\) 1.67 ab & 0.66 \(\pm\) 0.01 b & Nd & 173.76 \(\pm\) 26.02 b \\ \hline \hline \end{tabular}  
* MT: Melatonin. Nd: Not detected. Each data point represents the mean of three replicates (mean \(\pm\) standard error). Letters in the same column indicate differences at \(p<0.05\) significance level.  
\end{table} 
Table 2: Effects of exogenous melatonin application on biochemical parameters in dried apricots. The differential responses to various melatoninin concentrations emphasize the complexity of the fruit's physiological response to exogenous antioxidants and underscore the importance of fine-tuning treatment protocols for optimal efficacy. It is also worth noting that the absence of detectable melatoninin post-drying does not necessarily negate its beneficial effects. As suggested by [PERSON] [30] and [PERSON] et al. [39], melatonin may exert its protective influence through the activation of endogenous antioxidant systems or by triggering stress response pathways prior to its degradation. This hypothesis is supported by the persistent effects observed in oxidative stress markers and \(\beta\)-carotene content, despite the absence of detectable melatoninin in the final product.