شبیه سازی رفتار ترکیبات عطر فرار
Introduction
Material and methods
Results and discussion
Conclusion
References
Introduction
The diversity of distilled spirits consumed around the world is large. In Europe, the definition, description, labelling and protection of geographical indications of spirit drinks are specified in regulation 110/2008 (1). The standard unit for ethanol concentration is the alcoholic strength by volume (annex I point 11), or ABV (alcohol by volume) in % v/v. The distillation process concentrates the ethanol and volatile aroma compounds from the fermented must, as well as those formed in situ through chemical reactions (2). The quality and specific characteristics of a spirit beverage are highly dependent on the nature and concentration of the volatile compounds and, to a lesser extent, its ethanol concentration. The volatile compounds responsible for the overall aroma perception of spirit beverages belong to many chemical families, such as alcohols, carboxylic acids, esters and aldehydes (2). The precise relationship between volatile compounds and aroma perception is still difficult to assess, owing to the variable nature of volatile compounds, concentration relative to sensory threshold and possible synergies. The diversity of volatile compounds and differences in concentration is mainly due to the raw materials, fermentation method and the distillation process, which includes both the apparatus and the method (3,4). Three main methods are commonly used with a typical distillation apparatus: (a) continuous distillation in a multistage distillation column (e.g. rum, vodka, Armagnac, Calvados, neutral alcohol), (b) batch (simple discontinuous) distillation involving recycling (e.g. Cognac, Armagnac, Auge, Calvados, rum) and (c) batch distillation in a column involving recycling (fruit brandies). The preferred method depends on the organoleptic qualities desired. For instance, full-bodied, single malt whiskies are produced with a batch method in traditional pot stills, while lighter grain whiskies are produced in multistage distillation columns (5). According to Ferrari et al. (6), the behaviour of volatile compounds is different during distillation in pot stills and rectification columns. Indeed, in contrast to esters, it was observed that larger quantities of higher alcohols were recovered in the distillate in continuous distillation than in the simple batch process. This study focused on the behaviour of volatile compounds during simple batch distillation. This method is generally conducted in a traditional copper still, known as an ‘alambic charentais’ (Fig. 1) (3,7–9). Distillation is carried out in two successive cycles. During the first cycle, known as ‘wine distillation’, the wine is introduced into the boiler. An initial small fraction of distillate (‘heads’) is collected and separated. Distillation then continues until the ABV of the distillate reaches ~2% v/v. This second fraction constitutes the low wine, with ethanol concentration between 27 and 30% v/v. The second cycle is the low wine distillation. In analogy with wine distillation, the first fraction of distillate (‘heads’) with the highest ethanol concentration is removed.