## 3 Results and Discussion
### Spectrophotometric Assays in Cucumber Peel Samples during Storage  
The total phenolic content and antiradical and antioxidant activity of cucumber peels were determined on days 1, 7, 13, 16, 22, and 28 of storage using the Folin-Ciocalteu, ABTS, and FRAP spectrophotometric methods, and the results are presented in Table 3.  
The total phenolic content and antioxidant activity of cucumber peels varied insignificant until day 13 of the experiment and exhibited a significant (_p_ < 0.05) increase at day 16. Afterward, the total phenolic content remained relatively stable until the end of the storage period, whereas the antioxidant activity displayed a significant (_p_ < 0.05) increase at day 28. Additionally, the antiradical activity displayed a significant and progressive increase from day 13 to day 16, followed by a stabilization until the end of the storage period. Moreover, a strong positive correlation (_p_ < 0.05) was observed between the total phenolic content and both the antiradical and antioxidant activity (0.792 and 0.789, respectively). Additionally, a positive correlation was noted between antioxidant activity and antiradical activity (0.684). Interestingly, as the storage period progressed, a significant increase was observed in both the total phenolic content and antiradical/antioxidant activity. This finding may be possibly attributed to a number of factors. As the cucumber ripens, a gradual conversion of phenolic glycosides into aglycon structures with higher antioxidant activity may occur. Another explanation may be the gradual degradation of chlorophyll and the parallel increase in flavonoids and carotenoids, as reported by [PERSON] et al. [20], which occurred as the cucumber color changed from green to yellow (Table 1). Additionally, [PERSON] et al. [31] reported that cucumber peel extracts showed significant antioxidant and antimicrobial properties, which are largely attributed to their high flavonoid content. Moreover, since the cucumbers are protected by their packaging (Figure 1), the membrane structure of the cucumber peel remains intact and undamaged, and as a result, the phenolic compounds and polyphenol oxidase, which are present in different parts of the cell membrane, are unable to interact with each other. A similar conclusion was reached by [PERSON] et al. [32], who found that the total phenolic content and antioxidant activity of broccoli increased during storage at room temperature. Furthermore, cucumber preservation at 15 \({}^{\circ}\)C appears to result in enhanced storability and an extended shelf life [7]. Indicatively, an increase in the phenolic content and antioxidant activity during storage at temperatures comparable to those used in the present study has also been observed in other fruits and vegetables such as bananas, strawberries, and mangoes [13; 33; 34; 35].  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & **Day 1** & **Day 7** & **Day 13** & **Day 16** & **Day 22** & **Day 28** \\ \hline TPC (mg CAE/g peel) & 0.12 \(\pm\) 0.03 a & 0.12 \(\pm\) 0.01 a & 0.14 \(\pm\) 0.02 a & 0.20 \(\pm\) 0.02 b & 0.21 \(\pm\) 0.01 b & 0.23 \(\pm\) 0.03 b \\ \hline ABTS (mg Trolox (TE)/g peel) & 0.14 \(\pm\) 0.02 a & 0.16 \(\pm\) 0.01 ab & 0.17 \(\pm\) 0.01 b & 0.22 \(\pm\) 0.03 c & 0.19 \(\pm\) 0.02 c & 0.21 \(\pm\) 0.01 c \\ \hline FRAP (mg Fe (II)/g peel) & 0.12 \(\pm\) 0.01 a & 0.12 \(\pm\) 0.00 a & 0.13 \(\pm\) 0.02 a & 0.16 \(\pm\) 0.01 b & 0.15 \(\pm\) 0.02 b & 0.20 \(\pm\) 0.02 c \\ \hline \hline \end{tabular}  
* Different letters in the same row present statistically different values (_p_ < 0.05).  
\end{table}
Table 3: Total phenolic content (TPC), antiradical activity (ABTS), and antioxidant activity (FRAP) of cucumber peel during storage.