CHC ( Fig. 2a) shows a decrease on piceid and an increase in resveratrol contents
probably due to the β-Glucosidase activity, which was larger in these samples. The positive correlation observed between this enzymatic property and the level of this phenolic compound (R = 0.412, p = 0.05) for this group of samples Procaspase activation corroborate this hypothesis. For the CHA and CTA samples ( Fig. 2b and c), the effect of glucose concentration (10.41 g/L ± 0.58) is important too, because in these samples, the content of glucose was on average 45% higher than in CHC (6.88 g/L ± 0.65) and constant levels of piceid and a decrease on the resveratrol concentration were observed. In the first case, the stability can be explained by the occurrence of the reverse reaction, when an aglycone is released it returns to the form of its glucosylated derivative as described by Medina et al., 2010. The negative correlation observed between the glucose and resveratrol levels (R = −0.454, p = 0.05) reinforce this idea. The reduction in resveratrol contents may be due to photoisomerization and other enzymatic reactions, such as those mediated by phenoloxidases present in the medium or in which cofactors (e.g. metals) are involved in the formation of derivatives previously
identified in wine ( Prokop et al., 2006 and Stefenon et al., 2012). Furthermore, the concentration of both compounds mediated by the presence of β-Glucosidase PLX4032 can have a strong influence in the antioxidant activity as demonstrated by the clear relation between them ( Table 2). The tyrosol is a compound commonly found in chardonnay grapes (D’Incecco et al., 2004) and in the CHC samples
the content was initially high (Fig. 3a). Our data were similar to those found in Champagne samples ( Vauzour et al., 2010). Regarding the Champenoise method (varietal/CHC or assemblage/CHA) we can consider the level of tyrosol to be constant, because at the end of the ageing period studied, the level is similar to the one of the two analysed blocks. And the slight increase observed in CHC samples until 120 days diglyceride can explain the larger antioxidant activity in these SW. The influence of tyrosol over the IC50 is clear ( Table 2). Regarding the Charmat samples, a gradual increase was observed. As it is known, the complex array of aroma and flavour found in SW is largely originated from the grapes, yeast metabolism during the alcoholic fermentations and the ageing on lees ( D’Incecco et al., 2004 and Torrens et al., 2010). In this case, the most important variable seems to be the elaboration method, because the correlation between the tyrosol content and sur lie was opposite: Charmat (R = 0.917, p = 0.01) and Champenoise (R = −0.519, p = 0.01).