Comparison of the aroma profile in total and partial dealcoholisation of white and red wines by reverse osmosis

Abstract

The increasing demand for low-alcohol and non-alcoholic wines has led to the development of advanced dealcoholisation techniques aimed at preserving wine quality while reducing ethanol content. Reverse osmosis is one of the most widely used membrane-based processes for the selective removal of ethanol [1]. This separation technique uses a semi-permeable membrane to create an osmotic pressure gradient between two solutions. Normally, water moves through the membrane from a low to a high concentration solution to maintain equilibrium. However, applying sufficient pressure to the high-concentration side reverses this flow, allowing the solvent to move to the lower concentration side [2].

This study investigates the impact of total and partial dealcoholisation on the aroma profile of white and red wines treated by reverse osmosis. Wines were subjected to two levels of dealcoholisation: partial dealcoholisation, in which ethanol content was reduced by approximately 50%, and total dealcoholisation, in which ethanol content was reduced to approximately 0.5% v/v in white wine and 2% v/v in red wine. The volatile compound composition of treated and untreated wines was analysed using gas chromatography-mass spectrometry (GC-MS) coupled with multiple headspace solid-phase microextraction (MHS-SPME) [3]. The analysis focused on key aroma compounds, including esters, alcohols, and acids, which contribute to the wine’s overall sensory characteristics.

The results showed that partial dealcoholisation retained a higher concentration of volatile aroma compounds compared to total dealcoholisation. While reverse osmosis effectively removed ethanol, it also led to the loss of key aroma compounds, with total dealcoholisation resulting in a more pronounced decrease in esters. These compounds, responsible for fruity and floral aromas, were significantly reduced, altering the wine’s aromatic profile.

This study highlights the influence of the degree of dealcoholisation on wine aroma and demonstrates that partial dealcoholisation better preserves the volatile compounds essential for aromatic complexity. These findings improve the understanding of how the extent of dealcoholisation affects the aromatic composition of wine and provide valuable insights for winemakers seeking to develop reduced-alcohol wines with minimal losses of aromatic quality. Further research should explore optimisation strategies to enhance the retention of key aroma compounds during the dealcoholisation process.

References

[1] El Rayess, Y., & Mietton-Peuchot, M. (2016). Crit. Rev. Food Sci. Nutr., 56(12), 2005-2020.

[2] Schmidtke, L.M., Blackman, J.W., Agboola, S.O. (2012). J. Food Sci., 77, 25–41.

[3] Milheiro, J., Filipe-Ribeiro, L., Cosme, F., Nunes, F. M. (2023). Food Chem., 421, 136154.