Oenin Explained

Oenin is an anthocyanin. It is the 3-glucoside of malvidin. It is one of the red pigments found in the skin of purple grapes^[1] and in wine.^[2]

Color stabilization of malvidin 3-glucoside at a higher pH can be explained by self-aggregation of the flavylium cation and copigmentation with the Z-chalcone form.^[3] In the presence of procyanidin C2, the red color of oenin appears more stable. However, the HPLC chromatogram shows a decrease in the amplitude of the peaks of oenin and procyanidin C2. Concomitantly, a new peak appears with a maximal absorption in the red region. This newly formed pigment probably comes from the condensation of oenin and procyanidin C2.^[4]

Malvidin 3-glucoside alone is not oxidized in the presence of grape polyphenol oxidase, whereas it is degraded in the presence of a crude grape PPO extract and of caftaric acid forming anthocyanidin-caftaric acid adducts.^[5]

See also

• Phenolic compounds in wine
• Wine color
• Malvidin glucoside-ethyl-catechin
• Anthocyanone A, a degradation product of oenin found in wine

Notes and References

1. http://www.answers.com/topic/oenin Oenin on answers.com
2. News: Di Justo . Patrick . What’s Inside: Red Wine . Wired . Condé Nast . Aug 30, 2011 .
3. 10.1021/jp972320j. Color Stabilization of Malvidin 3-Glucoside: Self-Aggregation of the Flavylium Cation and Copigmentation with the Z-Chalcone Form. 1998. Houbiers. Chantal. Lima. João C.. Maçanita. António L.. Santos. Helena. The Journal of Physical Chemistry B. 102. 18. 3578.
4. 12010001. 2002. Malien-Aubert. C. Dangles. O. Amiot. MJ. Influence of procyanidins on the color stability of oenin solutions. 50. 11. 3299–305. Journal of Agricultural and Food Chemistry. 10.1021/jf011392b.
5. 10.1016/S0031-9422(97)00190-8. Reactions of polyphenoloxidase generated caftaric acid o-quinone with malvidin 3-O-glucoside. 1997. Sarni-Manchado. Pascale. Cheynier. Véronique. Moutounet. Michel. Phytochemistry. 45. 7. 1365.