Falconieri, M., Minceva, M. Thermodynamic insights into vacuum distillation dealcoholisation of beer and aroma compounds loss: A molecular-level analysis. Journal of Food Engineering 2027, 422, 113255. doi.org/10.1016/j.jfoodeng.2026.113255

Abstract

Vacuum distillation is a widely used process for beer dealcoholisation. While effective at reducing the alcohol content of non-alcoholic beer (NAB) below 0.05 vol%, it also causes significant loss of aroma compounds into the alcohol-rich distillate, altering the sensory profile of the resulting NAB relative to the original alcoholic beer. In beer, aroma compounds are present at very low concentrations, and their volatility is governed by their saturation pressures and activity coefficients.

In this study, the vapour–liquid equilibrium of a model beer mixture — comprising water, ethanol, and eight representative aroma compounds — was modelled using the Non-Random Two-Liquid activity coefficient model. A distillation column was simulated using the equilibrium-stage model in Aspen Plus v14. Non-volatile beer components and their interactions with aroma compounds were not modelled. Simulation results were validated against experimental data for three different beers processed in a pilot-scale distillation unit. The model reproduced the experimentally obtained ethanol and aroma compound concentrations in NAB and distillate, with an absolute average relative error (AAE%) between 6% and 9% for ethanol and 4% and 30% for the aroma compounds.

Results show that the volatility of aroma compounds and their distribution between the vapour and liquid phase are strongly influenced by their composition-dependent activity coefficients. As ethanol mole fraction decreases in the liquid phase from the top to the bottom of the column, activity coefficients of aroma compounds increase sharply. Conventional adjustments of process operating parameters, within typical production unit operating range, are unable to shift the mixture composition into a range that favours the retention of aroma compounds in NAB. This study provides the thermodynamic basis for predicting aroma compound concentrations in NAB and distillate for specific beer composition and vacuum distillation column operating conditions, supporting the design of vacuum distillation process modifications to improve NAB sensory profile.

Read the paper here.