Assessment of the effect of the non-volatile wine matrix on the volatility of typical wine aroma compounds by headspace solid phase microextraction/gas chromatography analysis.

BACKGROUND: The aim of this study was to evaluate the effect of the whole non-volatile wine matrix composition on the volatility of typical wine aroma compounds by comparing the slopes of regression lines of five deodorised and reconstituted wines with the slopes calculated for the same compounds in a control wine with no matrix effect.
RESULTS: The main effect observed was a reduction in the slopes, or a retention effect, that was largest for the reconstituted sparkling wine, which showed between 11 and 69% lower slopes than the control wine. In addition, an increase in the slopes, or a 'salting-out' effect, in the most compositionally complex reconstituted aged-red and sweet wines was also noticed for some volatiles with a very low boiling point or a low hydrophobic constant value.
CONCLUSION: This study has shown that the non-volatile composition of wines strongly affects the volatility of wine aroma compounds. In addition, the aroma chemical class, in particular its physicochemical properties (volatility and hydrophobicity), strongly influences this behaviour. On the basis of these results, many odour threshold values calculated in simple hydroalcoholic solutions and usually employed to evaluate the odour importance of specific volatile compounds may have been over- or underestimated.