# 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  
The color and the hue of the white must/wine samples are presented as follows. In the case of white wines, the absorbance value read at wavelength 420 nm, in relation to distilled water, represented an estimate of the oxidation state of the color, the so called 'color closure' [82]. The color parameters of the wine samples under study, the variation of absorbance at 420, 520 and 620 nm, as well as the C.I. and hue, are shown bellow in Figure 6. As a first notable aspect, the redness/red component of the wine sample, after 2 years' increase, was seen from the absorbance at 620 nm. The color properties/characteristics of the wine samples under study can be observed in Figure 6. Even if both studies' wines were white, the color properties were different. Moreover, for the Barzesti wine the color parameters, mainly the absorption values at 420, 520 and 620 nm increased with age (from 1 to 2 years) for both untreated (MB) and plasma treated samples (PB). Further on, the absorbance values of the untreated samples were greater than those for plasma treated ones. For these wine samples the color intensity (CI) increased with age and had greater value for the untreated samples unlike those treated. The Hue value depreciated over time for all wine samples, but it was with higher value for plasma treated ones. For the samples from Husi, the 420 nm absorbance fell off significantly, while for the 520 and 620 nm the absorbance slightly reduced its value. Moreover for these Husi wine samples the color intensity values also declined in time, as well as for the Hue parameter. However, the values were somehow bigger for plasma treated wines (PH). These aspects can be seen in Figure 6. Thus, having these values we could estimate the color differences between wine samples. As a notable fact, the Barzesti wine samples color were more intense unlike the Husi wine samples, that had close values for both untreated and plasma treated samples. The color parameters: CIELab, WI, chroma, angle hue and delta E (measured against the untreated must) of white wine are presented in the Table 5, shown below. Moreover the color parameters graphs (Figures 7 and 8) were obtained using the same method described in [83]. As reported by other researchers, a difference smaller than 3 of the wine sample color change, \(\Delta E^{*}_{ab}\), cannot be observed by human naked eye [107]. Figure 6: Colour parameters, C.I. and hue, for the untreated and plasma treated must. The effects of plasma treatment upon the color of the must samples under study are presented in the Table 5. As already seen in the UV-Vis absorption spectroscopy results, the two types of white must had different behaviour in respect to plasma treatment. The most noticeable plasma treatment results were upon the Barzesti samples. The \(L^{\star}\) parameter (lightness) increased after plasma treatment compared to the control, for both Barzesti and Husi samples. These changes in the values of the \(L^{\star}\) parameter were: for the Barzesti wine, the \(L^{\star}\) value depreciated by 8.5% after another one year (2y against 1y) for the control sample, while for the plasma treated one the decrease was by 4.3%. However, comparing the plasma treated wine after 1 year of storage with the control one, \(L^{\star}\) values were 11.5% higher, and after the second year of storage the difference was about 16.5%, so an extra 5% increase of the difference between control and treated with the aging of the wine, for the Barzesti wine. These differences were less noticeable in the case of Husi wine samples. More over, for the Husi samples \(L^{\star}\) tended to increase both over time and with plasma treatment, but with smaller percentages in comparison to Barzesti wines. More precisely, after 1 year of storage the \(L^{\star}\) for the treated samples was higher with almost 1.8%, and after another year with about 1.9%, so the value of \(L^{\star}\) remained constant over time.