# Helium Atmospheric Pressure Plasma Jet Source Treatment of White Grapes Juice for Winemaking
## 3 Results and Discussion
### Characterization of White Grapes juice and Wine
#### 3.2.1 UV-Vis Spectroscopy of White Grapes Juice and Wine  
As can be seen in Figure 4 the total wave range (200-1100 nm) revealed a typical waveform, as for the white wines reported in literature [61,62,108,109,110,111,10]. The spectral region from Figure 4 expressed the influence/contribution of specific organic compounds found in the wine samples. More precisely, for white wines the absorption spectra in the 240 to 400 nm region were related to the presence of esters and hydroxcinnamic acids (HCA), but correlations with pattern recognition techniques were recommended. Namely from 250 to 300 nm (around 280 nm) the absorption band was usually related to esters and different types of phenolic compounds (the absorption of benzene cycles of most of phenols), as for the 300 to 350 nm region, the band was associated with the presence of flavones and/or to nonflavonoid compounds and hydroxcinnamic acids [110]. For wines, the absorption spectrum in the UV-Vis region contained information about organic acids and phenolic compounds, including here hydroxcinnamic acids (227-245 nm, 310-332 nm), benzoic acids (235-305 nm), flavonoids (250-270 nm, 350-390 nm), anthocyannins (267-275 nm, 475-545 nm) or catechins (280 nm) [109,111].  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Method**} & \multicolumn{2}{c}{**T\({}_{rot}\) (OH)**} & \multicolumn{2}{c}{**T\({}_{rot}\)(N\({}_{2}^{+}\))**} & \multicolumn{2}{c}{**T\({}_{p}\)(N\({}_{2}\))**} & \multicolumn{1}{c}{**T\({}_{gas}\)**} \\  & **[K]** & **[K]** & **[K]** & **[\({}^{\circ}\)C]** \\ \hline Spectrum Analyzer & x & x & \(2265-2566\pm 190\) & x \\ Lifbase & \(340-350\pm 2\) & \(345-355\pm 2\) & x & x \\ IR camera & x & x & x & \(40\pm 1.5\) \\ k-type probe & x & x & x & \(35\pm 3.0\) \\ \hline \hline \end{tabular}
\end{table}
Table 3: Characteristic temperatures derived from the OES spectra of the plasma source and measured via IR and k-type thermocouple (mean \(\pm\) standard deviation).  
Water-related absorption bands were found between 920 nm and 1050 nm. These bands were related to the third overtone of O-H stretch (around 950 nm, usually in the case of fruits, vegetables and their juices, with 70--80% of water) and to the second overtone of O-H stretch (around 990 nm, sugars and organic acid related) [111]. Therefore it was convenient to measure these components and color of wines via UV-Vis absorption spectroscopy [112]. Another aspect was related to the oxidation degree of white wines, mainly to exposure to O\({}_{2}\) species, that could be followed up by means of HCA changes (usually these differences are easily observed in the first or second derivative of the UV-Vis spectra [48, 61, 62, 63, 64, 66, 68, 75].  
As far as one can see, the absorption spectra of wine samples (as in Figure 4) indicated that we had notable differences only in the case of MB-PB samples. For MH-PH samples, almost imperceptible differences could hardly be traced. It can be seen from Figure 4 that the absorption spectra of the untreated MB differed from the treated one PB but also from the MH-PH. Consequently, in the UV region the maximum for MB was at 215 nm, rather than at 230 nm as for PB and MH-PH. Moreover, a second peak centered at 280 nm for all samples, seemed more broadened for the MB samples, in contrast with the narrow and well defined peak seen in PB, MH and PH samples. Furthermore, in the 350-600 nm region for the MB-PB samples a difference in the Vis absorption spectra could be observed, and also for the 900-1100 nm part of the spectra.