Analysis of red wines with mass spectrometers and noses has revealed the chemistry behind their fruitiness
The interaction between the bewildering variety of ingredients in wine makes it difficult to tie compounds and flavours together, say Spanish researchers. But a surprising finding from Vicente Ferreira’s team at the University of Zaragoza could help producers achieve a more fruity bouquet.
Ferreira and colleagues carried out experiments studying (and smelling) five high quality, aged red wines1. The aim was to identify the compounds most likely to be involved in their ’aroma profiles’.
The wines were separated into their chemical constituents, which were identified using mass spectrometry, producing a long list of ingredients. The group then concocted chemical recreations of the wines, which were studied by a panel of expert sniffers.
’To analyse the compounds in the wine, we had to imitate the mixtures in different chemical environments,’ Ferreira told Chemistry World. ’We carried out 50 different sensory experiments with a sensory panel of 20 people in order to pinpoint the aroma-causing compounds.’
In previous work, Ferreira’s team had discovered esters responsible for wine’s berry fruit flavours2, but what they discovered in this new study added a surprising new dimension to their findings. Adding these fruity compounds to their wine made no perceptible difference to the aroma. Their continued study revealed that other ingredients suppressed or enhanced these flavours, controlling whether they could be detected by the human nose.
While ethanol has a strong suppressing effect on fruity odour, woody smelling hydrocarbons called norisoprenoids and dimethyl sulfide interact with the esters to boost it. ’This shows, for the first time, the importance of the interaction between these chemicals,’ said Ferreira. ’We already knew that ethanol inhibits fruity flavours, but we have now pinpointed other chemicals that enhance it. This opens a whole new prospect, allowing us to measure these compounds and evaluate how fruity a wine will be once it has aged.’
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1 A Escudero et al, J. Agric. Food Chem, DOI: 10.1021/jf0636418 S0021-8561(06)03641-7
2 E Campo et al, J. Chroma. A, 2006, 1137, 223