## 1 Introduction  
Four main methods are used to produce sparkling wine: the Charmat/Cuve closed/tank method; transfer method; carbonation of the base wine; and _Methode Champenoise_ (in Champagne only), though it is are referred to as the Traditional Method, Classic method, _Methode Traditionale_ or bottle-fermented in other parts of the world. Although the term bottle-fermented can also refer to the transfer method, in this study it refers to the Traditional Method whereby the second fermentation occurs in the bottle that is ultimately sold to consumers. There are two main production phases to Traditional Method sparkling winemaking as reviewed in [PERSON] et al. [1]: the first stage is the first fermentation of grape juice to convert it into base wine; the second stage is when the base wines go through a second fermentation in the bottle after the addition of yeast and sugar (_liqueur de tirage_). Following a period of aging on the yeast lees (_sur lies_), bottles are riddled to move the sediment to the neck. Yeast biomass is then expunged by freezing the lower part of the bottle's neck and removing the sediment. Prior to closing the bottle with a cork, _dosage_ (_liqueur d'expedition_) is inserted into each bottle and determines the final sweetness of the wine as well as a consistency in winery style. The _liqueur d'expedition_ is used to balance the wine and can also provide a wine with a unique flavour. Commonly referred to as _dosage_, it has been known to be produced using a range of sugar types (i.e., cane sugar, dextrose, beet sugar, liquid sugar or rectified concentrated grape must (RCGM)). Additionally, the wine used to make the _dosage_ (_+/ -_ sugar) can include the same wine as that being disgorged, another sparkling wine from the cell, oaked or unoaked still wine or wines aged in stainless steel or oak barrels depending on the required wine style of the winemaker [1,2]. Sparkling wines that do not have sugar added and are topped up with the same wine as that in the bottle are referred to in literature as _zero dosage_, _Brut zero_, _Brut naturel_, _Nature_ (<0.3%) or _Extra Brut_ (<0.6%). Although produced for many years, zero _dosage_ wines have recently increased in popularity [3]. Bottle-fermented sparkling wines range in sugar levels with _Brut_ wines tending to be adjusted with up to 1.5 \(w/v\) % sugar, whereas _Extra-sec_ generally contains 1.2%-2% sugar. _Sec_ wines commonly have between 2% and 4% sugar, _Demi-sec_ between 3% and 5% sugar and the now rare _Doux_ wines contain more than 5% sugar [3]. Residual sugar levels (RS g/L) are known to impact sparkling wine flavour but can cause an \"unbalanced\" wine if levels are too high or too low. Additionally, it was reported that sucrose strongly suppressed sourness in sparkling wines while subtly enhancing flavour [4]. The length of time between disgorging and release of sparkling wines from the winery is decided by the wine producer, but the flavour of sparkling wine after disgorging and _dosage_ addition is known to continuously change. The influence of grape variety, lees aging and bottle aging post-disgorging on volatile aroma compounds (VOCs) and foam has been studied [5], but sparkling wines were analysed 12 months after disgorging and did not have sugar added (zero _dosage_ wines topped with the same wine but without sugar addition). The authors of the manuscript reported that Albarino, Verdejo, Godello and Prieto Picudo were richest in most of the VOCs analysed, but Verdejo and Prieto Picudo had the best foam physiognomies. These characteristics were maintained during lees aging and in bottle after disgorging. However, to the authors' knowledge, no studies have investigated the impact of wine style or sugar addition used in the _dosage_ on VOCs during bottle aging post-disgorging. The disparity in the chemical nature and the concentrations of compounds in sparkling wines makes their analysis difficult [6].