## 3 Results and Discussion
### Antioxidant Capacity
#### 3.2.1 Radical Scavenging Activity as Determined by the Inhibition of the DPPH Radical Assay  
The free radical scavenging activity prior and after HRL treatments was evaluated by the DPPH assay [48]. The DPPH assay relies on the neutralization of a methanol-soluble stable radical by direct reduction via electron transfer or by radical quenching via H atom transfer even though the latter could be considered as marginal reaction since it occurs very slowly in methanol [49]. It was observed that the radical scavenging activity of the treated wines increased linearly with the relevant increase in the HRL amount. The equations of radical scavenging activity as determined with the DPPH Assay (A\({}_{\text{AR}}\)) for the wines treated and HRL amount (x) are presented in Figure 1. Regression analysis indicates that the A\({}_{\text{AR}}\) correlated well with the amount of HRL added. The conventional white vinifications of the same parcel in the two vintages examined, exhibited similar values of initial antioxidant capacity (A\({}_{\text{AR con 15'}}\): 0.62 \(\pm\) 0.01 mM TE; A\({}_{\text{AR con 14'}}\): 0.59 mM \(\pm\) 0.01 TE) considerably higher than the sulphite free vinifications (A\({}_{\text{AR nas15'}}\): 0.37 \(\pm\) 0.01 mM TE; A\({}_{\text{AR nas14'}}\): 0.49 \(\pm\) 0.01 mM TE). Differences in the A\({}_{\text{AR}}\) among sulphite free samples can be attributed to various factors such as vintage, vinification protocol, or oxygen uptake [2]. As presented in Table 4, treatment with 0.8 g/L HRL resulted in an increase in A\({}_{\text{AR}}\) by 30.8 to 55.8% for sulphite-free vinifications and 28.4 to 31.2% for conventional vinifications. Treatment with 1.6 g/L resulted in an increase ranging from 52.6% to 100.1%. A treatment of 0.8 g/L of HRL increased the radical scavenging activity of the wines without added sulphites to the level of the above mentioned activity of conventional wines indicating that HRL can have a positive effect on the A\({}_{\text{AR}}\) of white wines. The increase in antioxidant capacity of the samples was expected since aqueous and hydroalcoholic extracts of \(H\). _rhammoides_ leaves have been found to exhibit potent antioxidant capacity [19]. It must be noted however, that it would require at  
Figure 1: Radical Scavenging Activity via the inhibition of the DPPH radical vs. increasing HRL treatments in each wine. Error bars correspond to the standard error of the mean. least a 4 fold dose of the powdered HRL used in this study on the nas samples in order to reach the levels of Aar of conventional samples (0.4 g/L of HRL versus 115 ppm as Total SO\({}_{2}\)) demonstrating that sulphur dioxide was found to be a significantly more powerful radical scavenger than the HRL. Published data by [PERSON] et al. (2002) on the radical scavenging activity of 26 conventional commercial Greek white wines through the DPPH assay ranged from 0.47 to 0.60 mM TE (mean value: 0.52 mM TE) which were similar to the present study (range 0.43-0.62 mM TE; mean value 0.55 mM TE) but with minor differences on the assay protocol. On the same study [50] the authors reports values ranging from 0.53 to 0.58 mM TE for Moschofilero varietal wines. [PERSON] et al. (2015) [46] reported that a 0.3 g/L HRL treatment on a white wine made from cv. Savatiano resulted approximately in 3.5 fold increase in the wine antioxidant capacity as determined with the DPPH assay. A direct comparison among studies would not be considered as appropriate since in studies where biological raw materials are involved, numerous parameters may be simultaneously different [19; 51]. Previously published data indicate that the bioactive profile of the leaves can vary significantly according to cultivar of interest [27], sex [52], seasonal variation, cultivation practices, maturity level [24], and time of harvest [52; 53]. Thermal processing and grinding also play a key role. As [PERSON] et al.