# Comparative Assessment of Reverse Osmosis and Nanofiltration for Wine Partial Dealcoholization: Effects on Membrane Performance, Fouling, and Phenolic Compounds

## TL;DR

This study compares reverse osmosis and nanofiltration for reducing alcohol in red wine, finding that both methods preserve quality but differ in speed and phenolic compound retention.

## Contribution

The study introduces a comparative analysis of ACM3 and TS80 membranes for wine dealcoholization, highlighting their performance trade-offs in terms of speed, fouling, and phenolic retention.

## Key findings

- ACM3 at 25 bar with 2% ethanol reduction caused minimal phenolic changes and stable membrane performance.
- TS80 achieved faster processing rates but with higher phenolic loss and moderate fouling.
- Color changes in wine were linked to polymeric pigment shifts rather than anthocyanin loss.

## Abstract

This study evaluates the partial dealcoholization of red wine using reverse osmosis (ACM3) and nanofiltration (TS80) membranes at 25 and 35 bar, targeting 2% and 4% ethanol reductions. Membrane performance was assessed through fouling analysis and ethanol partitioning, while wine phenolic (flavan-3-ols, anthocyanins) and color characteristics (CIELab parameters) were determined. The 2% reduction process with ACM3 at 25 bar resulted in minimal phenolic changes. The 4% reduction process revealed distinct performance profiles: ACM3 exhibited exceptional stability (3.35–5.30% permeability loss, linear flux decline with R2 > 0.93) and ethanol rejection of 17.6–25.5%, while TS80 achieved processing rates three to six times faster with moderate fouling (16.3% loss, 7.7–13.3% rejection). Decreases in flavan-3-ols and anthocyanin concentrations correlated with fouling intensity rather than processing duration. Proanthocyanidin structure remained stable, and color shifts reflected changes in polymeric pigments rather than anthocyanin loss. Reverse osmosis at low transmembrane pressure proved most suitable for quality preservation. The operational trade-off is clear: TS80 offers three to six times faster processing but with greater phenolic loss, while ACM3 requires longer batch times with minimal fouling. Both processes demonstrate that membrane-based dealcoholization without fluid replacement is feasible, providing winemakers with a valuable method to reduce alcohol while preserving quality.