# Helium Atmospheric Pressure Plasma Jet Source Treatment of White Grapes Juice for Winemaking
## 3 Results and Discussion
### Characterization of White Grapes juice and Wine
#### 3.2.3 Colour of Must and Wine
For the \(a^{\star}\) and \(b^{\star}\) coordinates (\(a^{\star}\)-redness and \(b^{\star}\)-yellowness), a general increase value could be observed for Barzesti samples, while for the plasma treated ones of the Husi samples, a small decrease was seen ( 10% for \(a^{\star}\) and \(b^{\star}\)). The white index (WI) had an overall tendency of increase for all samples, both with age and plasma treatment. The same was true for chroma (\(C^{\star}_{ab}\)), with almost 25% enhancement, for the Barzesti control, and 18% for the plasma treated, although between control and treated samples there was a 50% difference in the control favour, while it was up to 10% for the Husi wines. The angular hue had similar tendency of decreasing over time, in the range of around 5%. The interesting result was related to the color differences (\(\Delta E^{\star}_{ab}\)) that for the Barzesti plasma treated samples was 20 in the first year of aging, and up to 27 in the second year. For the Husi wines, after 1 year \(\Delta E^{\star}_{ab}\)\(<\) 3 (no visible changes), and increased a bit, 4.6 after another 1 year. For better visualization of color parameter differences, the color space diagrams in \(L^{\star}a^{\star}b^{\star}\) and corresponding RGB coordinates, as resulted using Delgado-Gonzalez model [83], are presented in Figures 7 and 8. By using this model and the absorption (converted to transmittance) spectrum of the must and wine samples we were able to not only calculate the color coordinates of CIE \(L^{\star}a^{\star}b^{\star}\) and RGB color space but also to visualize these parameters in a way comfortable to the reader. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline
**Sample** & \(L^{\star}\) & \(a^{\star}\) & \(b^{\star}\) & WI & \(C^{\star}_{ab}\) & \(h_{ab}\) & \(\Delta E^{\star}_{ab}\) & **R** & **G** & **B** \\ \hline
1y MB & 85.49 \(\pm\) 0.03 & 6.43 \(\pm\) 0.02 & 39.19 \(\pm\) 0.03 & 57.72 \(\pm\) 0.06 & 39.71 \(\pm\) 0.06 & 80.68 \(\pm\) 0.09 & - & 250 & 208 & 138 \\
1y PB & 95.26 \(\pm\) 0.02 & 1.20 \(\pm\) 0.05 & 22.00 \(\pm\) 0.08 & 77.46 \(\pm\) 0.05 & 22.03 \(\pm\) 0.09 & 86.88 \(\pm\) 0.01 & 20.45 \(\pm\) 0.03 & 255 & 239 & 198 \\
2y MB & 78.22 \(\pm\) 0.07 & 12.18 \(\pm\) 0.04 & 48.34 \(\pm\) 0.06 & 45.60 \(\pm\) 0.02 & 49.85 \(\pm\) 0.01 & 75.85 \(\pm\) 0.06 & - & 241 & 183 & 102 \\
2y PB & 91.13 \(\pm\) 0.06 & 3.01 \(\pm\) 0.03 & 25.89 \(\pm\) 0.01 & 72.46 \(\pm\) 0.09 & 26.07 \(\pm\) 0.06 & 83.36 \(\pm\) 0.03 & 27.47 \(\pm\) 0.05 & 254 & 226 & 179 \\
1y MH & 84.75 \(\pm\) 0.05 & 8.48 \(\pm\) 0.02 & 42.98 \(\pm\) 0.09 & 53.62 \(\pm\) 0.05 & 43.80 \(\pm\) 0.04 & 78.83 \(\pm\) 0.07 & - & 252 & 204 & 129 \\
1y PH & 86.26 \(\pm\) 0.08 & 7.98 \(\pm\) 0.05 & 41.85 \(\pm\) 0.04 & 55.49 \(\pm\) 0.08 & 42.34 \(\pm\) 0.08 & 79.13 \(\pm\) 0.05 & 2.12 \(\pm\) 0.02 & 255 & 209 & 136 \\
2y MH & 85.64 \(\pm\) 0.04 & 8.95 \(\pm\) 0.08 & 41.75 \(\pm\) 0.07 & 54.95 \(\pm\) 0.03 & 42.70 \(\pm\) 0.05 & 77.90 \(\pm\) 0.01 & - & 255 & 206 & 134 \\
2y PH & 87.32 \(\pm\) 0.09 & 7.19 \(\pm\) 0.06 & 37.83 \(\pm\) 0.04 & 59.46 \(\pm\) 0.07 & 38.51 \(\pm\) 0.09 & 79.24 \(\pm\) 0.03 & 4.62 \(\pm\) 0.05 & 255 & 212 & 146 \\ \hline \end{tabular}
\end{table} 
Table 5: Plasma effect on color parameters: CIE \(L^{\star}a^{\star}b^{\star}\), WI, chroma, angle hue and \(\Delta E^{\star}_{ab}\) (measured against the untreated must) of white wine and the corresponding R G B coordinates (using equation system (1) and [83]), for 1 and 2 years old wine (mean \(\pm\) standard deviation). Figure 7: Color space for control (MB) and plasma treated (PB) Barzesti must, according to [83]. The black dots represent the points (\(a^{*}\), \(b^{*}\)) of the samples, while the red horizontal line in the bar graphs represents the \(L^{*}\), R, G and B of the 1 and 2 year old samples. The parameters \(L^{*}a^{*}b^{*}\) and RGB presented in Figures 7 and 8 are easily to follow on the graphs, where the differences between the studied wine samples are visualized simultaneously.