## 2 Results and Discussion
 \\ \hline
1 & Caffeic acid \(O\)-glucose I & 2.29 & 327 & 341 & 179 & 4.12 & 3.48 & 4.62 & 3.65 \\ \hline
2 & \(p\)-Coumaric acid \(O\)-glucose I & 2.39 & 302 & 325 & 163 & 227 & 2.76 & 3.00 & 2.35 \\ \hline
3 & Caffeic acid \(O\)-glucose II & 2.51 & 324 & 341 & 179 & 261 & 2.08 & 2.42 & 2.33 \\ \hline
4 & Caffeic acid \(O\)-glucose III & 2.66 & 329 & 341 & 179 & 0.89 & 0.63 & 0.87 & 0.86 \\ \hline
5 & Ferulic acid \(O\)-glucose & 2.73 & 314 & 355 & 193 & 0.64 & 0.37 & 0.79 & 1.13 \\ \hline
6 & Caffeic acid \(O\)-glucose IV & 2.85 & 324 & 341 & 179 & 0.72 & 0.70 & 0.83 & 1.18 \\ \hline
7 & 3-\(O\)-caffeoylquinic acid & 2.95 & 327 & 353 & 191 & 3.18 & 4.67 & 3.78 & 4.32 \\ \hline
8 & 5-\(O\)-caffeoylquinic acid & 3.09 & 327 & 353 & 191 & 1.74 & 1.63 & 2.09 & 1.96 \\ \hline
9 & \(p\)-Coumaric acid \(O\)-glucose II & 3.16 & 320 & 325 & 163 & 0.80 & 0.97 & 0.83 & 0.73 \\ \hline
10 & Caffeic acid & 3.27 & 327 & 179 & 119 & 0.53 & 0.56 & 0.56 & 0.61 \\ \hline
11 & Quercetin & \multirow{2}{*}{4.19} & Quercetin & \multirow{2}{*}{4.19} & \multirow{2}{*}{255.354} & \multirow{2}{*}{741} & \multirow{2}{*}{609.301} & \multirow{2}{*}{1.55} & \multirow{2}{*}{1.51} & \multirow{2}{*}{1.39} & \multirow{2}{*}{1.34} \\  & 3-\(O\)-rutinoside-7-O-pentoside & & & & & & & & \\ \hline
12 & Quercetin 3-O-rutinoside & 4.56 & 255.355 & 609 & 301 & 1.43 & 1.21 & 1.69 & 1.63 \\ \hline  & Total & \multirow{4}{*}{NOTE: mean values marked with different lowercase letters are significantly different at \(p<0.05\). of caffeic acid derivatives, the most significant changes were noted. In the case of Caffeic acid \(O\)-glucoside, the largest decreases were noted. This clearly indicates that hydrogen peroxide affects plant defense mechanisms in a different way than gaseous ozone. This is understandable because hydrogen peroxide occurs naturally in plant tissues as a response to the occurrence of agrophages [37], and its transformation is particularly intensive in peroxisomes [38]. Interesting results were obtained by using hydrogen peroxide and gaseous ozone fumigation together (Table 3). It was observed that the use of 1% hydrogen peroxide in combination with gaseous ozone at a concentration of 2 ppm for 1.5 min caused the greatest increase in the content of phenolic compounds, which amounted to \(\sim\)20%. This indicates a certain synergy of these two factors, however, occurring in a narrow range of concentrations of these factors. Increasing the ozonation time or hydrogen peroxide concentration caused this increase to be smaller (Table 3). Selected phenolic compound biosynthesis pathways were also modified, similarly to the use of only ozonation or hydrogen peroxide. Large differences were observed for caffeic acid derivatives, but in the case of other compounds, the results were also diversified, especially for \(p\)-Coumaric acid \(O\)-glucose. The synergistic interaction between gaseous ozone (O\({}_{3}\)) and hydrogen peroxide (H\({}_{2}\)O\({}_{2}\)) solution plays a significant role in promoting the biosynthesis of phenolic compounds in tomato fruits. Phenolic compounds are crucial secondary metabolites with antioxidant properties, beneficial for plant defense. Combined treatment with O\({}_{3}\) and H\({}_{2}\)O\({}_{2}\) leads to a marked enhancement in phenolic content, surpassing the effects observed when either is applied alone. This phenomenon can be explained by the activation of key enzymes involved in the plant's metabolic and defensive responses, specifically phenylalanine ammonia-lyase (PAL), catalase (CAT) and superoxide dismutase (SOD). Additionally, ozone dissolved in cellular fluids can be scavenged by phenolic compounds rich in unsaturated