Partial dealcoholisation of red wines by membrane contactor technique: influence on colour, phenolic compounds and saliva precipitation index

In this study, red wines from different grape varieties (Merlot, Aglianico and Piedirosso) and containing different alcoholic level (from 13.67 to 15.46% v/v) were treated to diminish the alcoholic percentage of 2, 3 and 5% v/v by a polypropylene hollow fibre membrane contactor apparatus. The wines were analysed before and after partial dealcoholisation. Colour indexes and phenolics were analysed by spectrophotometric methods and HPLC. Wine astringency was evaluated by an astringency index based on the ability of treated wines to precipitate salivary proteins (SPI, Saliva Precipitation Index). For all the levels of dealcoholisation studied, changes in chromatic characteristics, Folin-Ciocalteu index and vanillin reactive flavans were below the methodological errors of the analyses. A loss of malvidin 3-monoglucoside was detected after the dealcoholisation process. Decreasing the ethanol content of wines caused an increase in SPI values.