## 3 Results and Discussion

\begin{tabular}{c c c c c} \hline \hline
**Storage** & **Treatment** & **0 ds** & **8 ds** & **15 ds** & **23 ds** \\ \hline \multirow{4}{*}{Room temperature} & NPs Cu & 35.69 \(\pm\) 0.40 a & 30.90 \(\pm\) 0.75 b & 37.88 \(\pm\) 0.60 a & not done \\ \cline{1-1}  & NaCl & 35.14 \(\pm\) 0.86 ab & 26.81 \(\pm\) 0.71 d & 33.64 \(\pm\) 0.60 f & not done \\ \cline{1-1}  & NPs Cu + NaCl & 34.94 \(\pm\) 0.91 ab & 29.50 \(\pm\) 0.58 c & 35.14 \(\pm\) 0.48 de & not done \\ \cline{1-1}  & T0 & 34.19 \(\pm\) 0.65 b & 32.60 \(\pm\) 0.71 a & 36.83 \(\pm\) 0.60 b & not done \\ \hline \multirow{4}{*}{Refrigation} & NPs Cu & not done & 31.25 \(\pm\) 1.14 b & 36.63 \(\pm\) 0.46 bc & 38.08 \(\pm\) 0.78 a \\ \cline{1-1}  & NaCl & not done & 30.75 \(\pm\) 0.65 b & 34.84 \(\pm\) 0.35 e & 35.04 \(\pm\) 0.69 bcAt eight days, the fruits of the T0 plants had the highest total phenol content for both storage conditions. In addition, the fruits of plants with saline stress stored at room temperature had the lowest content. However, the application of Cu NPs in plants with saline stress had a higher content of phenols in fruits than those of plants with NaCl alone. This suggests that the application of Cu NPs decreases the adverse effect of NaCl on fruits, avoiding the loss of total phenols. In addition, refrigeration also has this effect, since treatments including both NaCl and Cu NPs are not different from each other. At 15 days of storage, the fruits of the plants with application of Cu NPs presented the highest contents of total phenols for both storage conditions. In contrast, the fruits of plants with saline stress had the lowest total phenol content in both cases. It was also observed that the application of Cu NPs in plants with NaCl stress induced higher content of total phenols in fruits compared to plants that were only under saline stress. This corroborates that the application of Cu NPs reduces the adverse effect caused by saline stress, reducing the loss of total phenols in tomato fruits especially when stored at room temperature. Finally, at 23 days of refrigerated storage, it was observed that the fruits of the plants with application of Cu NPs presented the highest total phenols content. This indicates that the application of Cu NPs has a positive effect on the total phenols content in tomato fruits and on the conservation of these compounds through storage time. Total phenols are antioxidants that trigger a series of secondary metabolites synthesized through the pathway of the shikimic acid or malonic acid, exerting cellular signaling functions under conditions of abiotic stress [29]. The main phenolic compounds found in tomato are the flavonoids rutin, naringenin, naringenin chalcone, and quercetin and the hydroxycinnamic acids chlorogenic and caffeic acids [1]. However, these exist in different concentration in the fruits due to the structural diversity among the phenolic compounds [3]. These compounds give the antioxidant capacity in the fruits due to the reduction of oxidative changes in cells by reducing the levels of free radicals [3]. It is suggested that Cu NPs have a stimulatory effect on the induction of antioxidant compounds derived from stress within the cells [11]. This may result in the formation of phenols as observed in this work. The phenolics derived from aromatic amino acids and their precursors are some of the very wide range of compounds derived from shikimic acid. These compounds are a group of structurally diverse plant secondary metabolites that include terpenoids, phenylpropanoids, cinnamic acids, lignin precursors, hydroxybenzoic acids, catechols, coumarins, flavanoids, isoflavuoids, and tannins [30]. These varieties of metabolites are very important in stress tolerance by plants [3], and their accumulation are a good response in plants. The content of flavonoids in tomato fruits was also statistically different between treatments at all evaluation times and for both storage conditions (Table 2).