## 3 Results and Discussion
### Phenolic Content
\begin{table}
\begin{tabular}{c c c c c c c} \hline  & **Compound** & \multicolumn{6}{c}{**Time (min)**} \\  & & **0** & **10** & **20** & **30** & **120** \\ \hline Flavan-3-ols & Catechin & 46.6 ab & 40.5 bc & 48.8a & 36.9c & 26.8d \\ Epicatechin & 365a & 353 ab & 398a & 303b & 229c \\ Procyanidin dimer B1 & 40.1a & 37.8a & 39.0a & 31.2b & 17.8c \\ Procyanidin dimer B2 & 138a & 135 ab & 141a & 113b & 70.9c \\ Procyanidin dimer B4 & 9.61a & 9.86a & 9.40 ab & 7.63b & 4.63c \\ Procyanidin B trimer & 8.62a & 8.14a & 7.81a & 6.57b & 3.53c \\ Procyanidin B trimer 2 & 15.3a & 14.8a & 14.4a & 11.4b & 7.01c \\ Procyanidin B trimer 3 & 49.6a & 49.0a & 46.3a & 37.0b & 20.3c \\ Procyanidin B trimer 4 & 7.00a & 7.30a & 6.50 ab & 5.40b & 2.68c \\ Procyanidin B trimer 5 & 0.39b & 15.05a & 13.52b & 0.14b & 0.05b \\ \hline Hydroxycinnamic acids & Caffe acid & 0.96a & 0.55b & 1.13a & 0.98a & 1.02a \\ Caffeolyticnic acid isomer 1 & 292b & 384a & 291b & 263 bc & 238c \\ Caffeoylquinic acid isomer 2 & 613 bc & 832a & 685b & 620 bc & 591c \\
4-Coumaroyl quinic acid & 91.9a & 99.2a & 97.7a & 77.9b & 80.8b \\  & Coumaroyl quinic acid & 247b & 302a & 268 ab & 257a & 283 ab \\ \hline Dihydrochalcones & Phloretin-2\({}^{\prime}\)-O-(2\({}^{\prime\prime}\)-O-xylosyl) & 145b & 196a & 187a & 197a & 139b \\  & glucoside & & & & & \\ Phloreidin & 35.7c & 49.9 bc & 54.5b & 81.2a & 25.8c \\ \hline Flavonols & Myricetin rhamnide & 2.89 bc & 4.95a & 3.64b & 2.94 bc & 2.30c \\ Quercetin & 2.77 bc & 4.22a & 3.49 ab & 3.55a & 2.33c \\ Quercetin-O-glucose & 2.90b & 6.22a & 3.70b & 2.97b & 2.28b \\ Quercetin-O-rhammoside & 27.0b & 37.2a & 32.8 ab & 33.2a & 24.2b \\ Rutin & 0.13a & 0.06 ab & 0.14a & 0.05b & 0.00c \\ \hline Total phenolics & & 2142b & 2588a & 2352 ab & 2092b & 1774c \\ \hline \end{tabular}
\end{table} 
Table 2: Content of phenolics (\(\mu\)mol kg\({}^{-1}\) f.w.) of Pink Lady apples, as affected by plasma treatment time. after 10 min of treatment; however, this fact does not suggest the occurrence of any enzyme-mediated release of procyanidins, because the content of B2 dimeric procyanidin has to increase as a consequence of enzymatic hydrolysis [35; 37]. However, since cell walls' polysaccharides form a higher number of complexes with procyanidins that have high molecular weight rather than those with low molecular weight [38], the increase of trimeric procyanidins (17%), which could be caused by a polymerization reaction upon oxidation, could also have been influenced by the enzymatic-mediated release from the complexes of cell walls' polyphenols after 10 min of processing. Chlorogenic acid (caffeoylquinic acids isomers) and phloridzin showed a 30 and 40% increase of their initial concentration after 10 min of cold plasma treatment. The increase of hydroxycinnamic acids and chalcones in plant tissues is associated with the wounding response which induces an increase in the content of phenolic compounds, likely due to their biosynthesis through the phenyl-propanol pathway as a plant defense mechanism [39; 40]. Selected antifungal polyphenols, such as chlorogenic acid, isochlorogenic acid, chalcones, and especially phloridzin, could be synthesized after an elicited increased activity of the key enzymes (phenylalanine ammonia lyase and chalcone synthase) of the phenyl-propanol biosynthetic pathway [39; 41]. The increase of these compounds may also partly be due to the activity of hydrolases, although according to some previous studies [32; 34], a dramatic increase of caffe acid should also be observed, which is contrary to our results. On the other hand, the increase of phloridzin and rutin that we found are in agreement with enzyme-assisted hydrolysis [35]. Moreover, the increase in quercetin and quercetin glucoside observed after 10 min of plasma treatment could be a consequence of hydrolysis of the cell wall [37].