Compound NJ2 is a xanthylium yellowish pigment found in wine.
In model solutions, colorless compounds, such as
catechin
Catechin is a flavan-3-ol, a type of secondary metabolite providing antioxidant roles in plants. It belongs to the subgroup of polyphenols called flavonoids.
The name of the catechin chemical family derives from ''catechu'', which is the tanni ...
, can give rise to new types of pigments. The first step is the formation of colorless
dimeric compounds consisting of two
flavanol
Flavan-3-ols (sometimes referred to as flavanols) are a subgroup of flavonoids. They are derivatives of flavans that possess a 2-phenyl-3,4-dihydro-2''H''-chromen-3-ol skeleton. Flavan-3-ols are structurally diverse and include a range of com ...
units linked by carboxy-
methine
In organic chemistry, a methine group or methine bridge is a trivalent functional group , derived formally from methane. It consists of a carbon atom bound by two single bonds and one double bond, where one of the single bonds is to a hydrogen. ...
bridge. This is followed by the formation of
xanthylium salt yellowish pigments and their
ethylesters, resulting from the dehydration of the colorless dimers, followed by an oxidation process. The loss of a water molecule takes place between two A ring
hydroxyl groups of the colorless dimers.
[Xanthylium salts formation involved in wine colour changes. Nour-Eddine Es-Safi, Christine Le Guernevé, Hélène Fulcrand, Véronique Cheynier and Michel Moutounet, International Journal of Food Science & Technology, February 2000, Volume 35, Issue 1, pages 63–74, ]
See also
*
wine color
The color of wine is one of the most easily recognizable characteristics of wines. Color is also an element in wine tasting since heavy wines generally have a deeper color. The accessory traditionally used to judge the wine color was the tastevin, ...
*
Phenolic content in wine
The phenolic content in wine refers to the phenolic compounds—natural phenol and polyphenols—in wine, which include a large group of several hundred chemical compounds that affect the taste, color and mouthfeel of wine. These compounds include ...
References
Polyphenols
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