Why some red wines taste ‘dry’: Cabernet Sauvignon contains more, larger and more highly pigmented tannins which mix with saliva to influence the astringency of a bottle than a Pinot Noir
- The compound tannin in has long been known to influence dryness in wines
- Scientists suspected it was down to tannin and its interactions with saliva
- They extracted the compound from two red wines with different dryness levels
- The drier version had a larger pigmented tannin which formed more protein
- When they added this version to other beverages, their dryness score rose too
An interaction between tannins in wine and your saliva could finally explain why some are deemed ‘drier’ than others, a new study shows.
While the compound tannin has long been associated with the mouthfeel, exactly how it causes it has never been pin pointed.
Tannin extracted from drier wines such as Cabernet Sauvignon was shown to be larger and more highly pigmented than those in the less dry Pinot Noir.
When this ‘drier’ tannin was added to control drinks, it promoted perceptions of dryness.
The findings could help winemakers better manage wine tastes, say researchers.
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An interaction between tannin in wine and your saliva could finally explain why some are deemed ‘drier’ than others, a new study shows (Stock image)
WHAT IS TANNIN?
Tannin, also called tannic acid, is a pale-yellow to light-brown substances.
It is widely found occurring naturally in in the roots, wood, bark, leaves, and fruit of many plants.
Tannin is also called tannic acid
Tannin solutions have an astringent taste and is responsible for the astringency, colour, and some of the flavour in tea.
They are used in the clarification process of wine and beer but is mainly used in tanning leather, dyeing fabric, making ink, and in various medical applications.
Tannins are known to bind to proteins and amino acids causing them to aggregate and precipitate.
The chemical tannin is found in tea and naturally occurring in high quantities in grapes and pomegranates.
In the latest study, researchers from the American Chemical Society explored how tannins from different wines interact with other characteristics of the beverages, as well as with salivary proteins, to influence dryness perception.
The dryness sensation, also known as astringency, refers to a puckering or rough feeling in the mouth when someone drinks wine.
According to the authors of the paper: ‘Scientists know that wine drinkers perceive astringency when tannins and salivary proteins interact, aggregate and precipitate, which makes the mouth less lubricated.’
But exactly how these reactions create their characteristic feel had not been explained.
To do so, they extracted tannins from a dry cabernet sauvignon and a less-dry pinot noir and analysed the compounds in them.
The authors noted: ‘The dryness of red wines was related to larger tannins, higher tannin concentration, and a greater turbidity with saliva.’
When scientists swapped the tannin in the two wines – adding the cabernet tannins to the pinot and vice versa, taste experts did not however detect any changes in dryness compared to previously.
While the compound tannin has long been associated with ‘mouthfeel’, exactly how it does it has never been pin pointed. In the latest study, tannin extracted from drier wines was shown to be differ in both form and concentration, and promoted dryness when added to other drinks
‘The dryness was not affected by the addition of tannins into wine probably as a result of the aroma/taste suppression effects and the presence of other component,’ added the scientists.
To test their theory, the scientists added the compound to control beverages that did not have distinct aromas, unlike the two red wines.
They added the ‘drier’ cabernet tannins to simple ‘model’ wine – composed only of the chemical ethanol and tartaric acid in water.
When the expert tasters were asked to rate their dryness, they gave higher scores than that for the original control drinks.
It is therefore likely in the first experiment, the characteristic aroma of the two red wines influenced the tasters’ perception of dryness, and prevented them from noticing the effect of the added tannins.
The results could help winemakers manage dryness perception based on wine composition and tannin characteristics, the researchers say.
The full report is published in the Journal of Agricultural and Food Chemistry.
