GC-MS head space and consumer preference evaluation of wines with reduced ethanol content

Reducing the ethanol content of wine without affecting its flavour is a challenge for wine makers. Although various processes exist for ethanol reduction, loss of aroma compounds during processing cannot be completely prevented. In addition, ethanol concentration has an impact on the profile of volatile compounds present in the headspace. Thus, a reduction in ethanol may affect the headspace composition.The objectives of this research were (i) to reduce the ethanol content in three wines using a commercially available technology, (ii) to assess the effect of ethanol reduction on wine headspace composition and (iii) to determine the preference of consumers for both reduced ethanol and the original wine. Ethanol reduction was performed using a Memstar Micro unit that sequentially uses reverse osmosis and evaporative perstraction to reduce ethanol content. Trials were performed on three commercial wines, two white wine varieties (Chardonnay and Sauvignon Blanc) and one red variety (Shiraz). The original ethanol content of Chardonnay, Sauvignon Blanc and Shiraz was 12.21 %, 9.91 % and 13.67 % respectively. Ethanol content was reduced to 8 % and 5 %. Samples of the 5 % ethanol content wines from the three varieties were adjusted back to original ethanol content (called readjusted samples) for aroma analysis. Headspace solid phase micro extraction gas-chromatography and mass spectrometry (HS-SPME/GC-MS) technology was used to develop a method to analyse 27 important wine aroma compounds. This method was used to determine the headspace composition of the three original wines, the 5 % and 8 % samples and the readjusted wine samples.