## 3 Results and Discussion
### Five Weeks Post-Disgorging  
At 5 weeks post-disgoring, BS had lower levels of alcohols than ZD. It was also higher in ethyl hexanoate and ethyl butanoate but lower in ethyl octanoate and ethyl isobutyrate than ZD (Table 5). All VOC concentrations in the treatment wines, except ethyl butanoate, were found to be significantly different statistically (\(p<0.05\)) at 5 weeks post-disgoring. Ethyl-2-methylbutyrate was not detected in BS but was reported in Chardonnay sparkling wine enriched with glycosylated precursors at 3.3 \(\mathrm{\SIUnitSymbolMicro g}\)/L even though in the German study sugar was not added after disgorging [23]. Differences in VOCs found in ZD compared to BS were detected in small concentrations at 5 weeks' post-disgorging which suggests that at levels of 8 \(\mathrm{g}\)/L (\(\pm 2\)) residual sugar, concentrations of alcohols and some ethyl ester branched acid derivatives were impacted. At this stage, ethyl isovalerate and ethyl hexanoate were found to be lower in ZD than BS. However, the introduction the _dosage_ solution (+sugar) into the bottles increased ethyl isobutyrate, ethyl isovalerate, and ethyl hexanoate, whereas BS had the lowest ethyl octanoate. The high concentration of 2-phenylethanol (fermentation/yeast-derived VOC) in OC was likely due to extraction from oak during the production process of the wine used in the _dosage_ solution [24]. UC had the lowest 1-hexanol and B had the lowest 2-phenylethanol. The leaf aldehyde, 1-hexanol, was found in the highest concentration in B, likely due to high concentrations in the brandy from the production method, and/or due to the ripeness level of the base material. Additionally, B had the lowest concentration of 2-phenylethanol.  
PN wines had the highest ethyl isobutyrate, ethyl-2-methylbutyrate, and ethyl isovalerate, though the lowest ethyl hexanoate concentration. IW was found to have the lowest concentrations of ethyl isobutyrate, ethyl butanoate and ethyl-2-methylbutyrate. BS had the lowest ethyl octanoate and UC the lowest ethyl isovalerate. IW was found to have the lowest concentrations of ethyl isobutyrate, ethyl butanoate, ethyl-2-methylbutyrate and 1-hexanol.  
Interestingly, B had the highest concentration of 4 of the 8 VOCs analysed: ethyl butanoate, ethyl hexanoate, ethyl octanoate and 1-hexanol. Of the monocarboxylic acid esters, the most important in brandy are those based on ethanol and saturated carboxylic acids, such as hexanoic (caproic), octanoic (caprylic) and decanoic (capric) acids [25]. In our study, the ranges of ethyl hexanoate and ethyl octanoate were 132-1687 \(\mathrm{\SIUnitSymbolMicro g}\)/L and 349-23,429 \(\mathrm{\SIUnitSymbolMicro g}\)/L, respectively, with B having the highest concentration of both compounds. Our results for these compounds are higher than those reported in Cava wines (produced from Chardonnay grapes), which is most likely due to the inclusion of brandy in one of our treatment wines [26]. However, it is unclear in the study as to whether a sugar _dosage_ solution was added to the Cava wines. It is important to state that previous studies of sparkling wine VOCs have focused on base wines, aged wines, vineyard soil types, and grape maturity [26; 27; 28; 29]. Few peer-reviewed studies on sparkling wines have stated the ingredients of the _dosage_ solution, the time after disgorging that the VOC analysis took place or have examined sparkling wine aroma development post-_dosage_ addition. Although [PERSON] et al. [5] analysed VOCs in sparkling wines at 12 months post-disgoring, the wines did not have a sugar addition after disgoring (zero _dosage_), and were also produced from varieties not included in our study.