## 2 Results and Discussion
### Chlorophylls (Chl) Content  
Table 2 shows the values of chlorophyll a, b, and total chlorophyll measured in the rocket samples treated with PAW and compared to the untreated sample. The total chlorophyll content of the untreated sample was 243 mg/100 D.W. This value is lower compared to the one reported by [46] for both garden and wild rocket. However, the chlorophyll content can vary quite substantially depending on the cultivar and on the physiological state of the tissue.  
After PAW immersion, a slight decrease was observed in Chl-a content, but it was only significant after the longer treatment (PAW-20), where a 30% reduction was observed. Instead, Chl-b showed a slight increase after the shortest treatment (PAW-2) (+23%) but then remained relatively constant during the longer immersion times. The total chlorophyll content showed significantly lower values compared to the untreated sample after 5 and 20 min.  
On one side, the degradation of chlorophyll can be favoured by the presence of oxygen radicals that promote the oxidation of the pigments. On the other side, the increase in Chl-b after 2 min of immersion could be explained by an increased extractability due to cell structure breakdown. Hence, the total amount of chlorophylls can be considered a result of the balance between higher extractability and oxidative degradation. A reduction in chlorophyll content was also observed by [53] on kiwi fruit slices exposed to a DBD plasma treatment. The authors observed a 15% reduction on Chl-a, which was attributed to the Type II breakdown mechanism (chemical breakdown). This variation, however, did not affect the colour of the samples. However, a variation in the colour parameters in rocket samples immersed in PAW has been previously reported, in particular a decrease in the luminosity of red and green indexes was observed for all samples, from 2 to 20 min immersion [14]. We can therefore assume that this variation could be partly related to the partial degradation of chlorophyll, which is the main pigment in rocket leaves.  
As shown previously [14], increasing treatment time from 5 to 20 min did not bring any significant improvement to the microbial decontamination of rocket leaves for the considered microbial species. Therefore, on one side, it could be considered useless to prolong the treatment above 5 min; however, as the results obtained in the present research  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **Control** & **PAW-2** & **PAW-5** & **PAW-10** & **PAW-20** \\ \hline Chla & 145.0 \(\pm\) 4.1 \({}^{\text{a}}\) & 114.4 \(\pm\) 15.2 \({}^{\text{ab}}\) & 111.4 \(\pm\) 21.6 \({}^{\text{ab}}\) & 131.6 \(\pm\) 9.3 \({}^{\text{ab}}\) & 102.4 \(\pm\) 8.4 \({}^{\text{b}}\) \\ Chlb & 98.5 \(\pm\) 13.4 \({}^{\text{b}}\) & 121.9 \(\pm\) 17.3 \({}^{\text{a}}\) & 95.9 \(\pm\) 11.8 \({}^{\text{b}}\) & 111.6 \(\pm\) 3.3 \({}^{\text{ab}}\) & 100.4 \(\pm\) 14.4 \({}^{\text{ab}}\) \\ Total & 243.4 \(\pm\) 17.1 \({}^{\text{a}}\) & 236.3 \(\pm\) 32.3 \({}^{\text{a}}\) & 207.3 \(\pm\) 32.1 \({}^{\text{b}}\) & 243.2 \(\pm\) 12.6 \({}^{\text{a}}\) & 202.7 \(\pm\) 22.8 \({}^{\text{b}}\) \\ \hline \hline \end{tabular}  
* Means that do not share letters for each compound differ significantly (\(p\) < 0.05) according to [PERSON]’s test. Legends: PAW-2, PAW-5, PAW-10, and PAW-20 refer to rocket samples subjected to plasma activated water (PAW) treatment for 2, 5, 10, and 20 min, respectively.  
\end{table}
Table 2: Changes in chlorophyll a (Chla), b (Chlb), and total chlorophyll contents of PAW treated rocket-salad samples at different processing times compared to control samples.  
have shown, the choice of the treatment time should also take into account the effect on the nutritional parameters in order to maximise the overall quality of the final product.