Evolution of Volatile Compounds during the Distillation of Cognac Spirit

Abstract

Cognac wine spirit has a complex composition in volatile compounds which contributes to its organoleptic profile. This work focused on the batch distillation process and, in particular, on volatile compounds specifically produced by chemical reactions during the distillation of Cognac wine spirit, traditionally conducted in two steps with charentais pot stills. The aim of this study was to characterize these volatile compounds formed during distillation. Sampling has been performed on the distillates and inside the boiler during a typical Cognac distillation. The analysis of these samples allowed us to perform a mass balance and to point out several types of volatile compounds whose quantities strongly increased during the distillation process. These compounds were distinguished by their chemical family. It has been found that the first distillation step was decisive for the formation of volatile compounds. Moreover, 2 esters, 3 aldehydes, 12 norisoprenoids, and 3 terpenes were shown to be generated during the process. These results suggest that some volatile compounds found in Cognac spirit are formed during distillation due to chemical reactions induced by high temperature. These findings give important indications to professional distillers in order to enhance the product's quality.

Batch distillation of spirits: experimental study and simulation of the behaviour of volatile aroma compounds

“…As observed previously by several authors , the mass balance ratio for alcohols at high concentrations is close to 1. However, for many volatile compounds present at low concentrations, outputs were often lower than inputs (Out/In <1).…”

“…In order to assess the potential of the simulation tool to represent wine and low wine distillations in a standard size copper still (2500 L), experimental data from Awad et al . were used as reference. The simulation module was configured as reported previously (three intermediate trays with 0.1 kg retention and 0.63 efficiency, a cooler with 0.1 kg retention, and a boiler with 0.9 efficiency).…”

“…Experimental data obtained in a previous study by Awad et al . were used to assess the potential of the simulation software to represent the experimental data obtained using a standard size copper still (2500 L), the maximum capacity authorised for Cognac distillation . Supplementary data measured (but not published) by these authors (gas pressure, distillate strength and flow rate) were also used here for comparison purposes.…”

“…This method is generally conducted in a traditional copper still, known as an ‘alambic charentais’ (Fig. ) . Distillation is carried out in two successive cycles.…”

“…Awad et al . characterised the volatile compounds produced by chemical reactions during the batch distillation of Cognac in an industrial scale alembic (2500 L), using real wines and low wine. Sampling and analysis of the initial wine and low wine and the distillate fractions and residues, as well as volume measurements, provided data for mass balances.…”