Phenolic compounds
Phenolic compounds are a diverse group of chemical substances in wine derived primarily from grape skins, seeds, stems, and from contact with oak during ageing[1]. They play a central role in defining the sensory qualities, stability, and ageing potential of wines.
Background
Phenolic compounds are secondary metabolites of plants that contribute to colour, flavour, and mouthfeel in wine[2]. Their concentration and composition vary by grape variety, viticultural practices, and winemaking methods. White wines generally contain fewer phenolics than red wines due to reduced skin contact during fermentation.
Types of Phenolics
Phenolic compounds in wine are broadly divided into flavonoids and non-flavonoids.
Flavonoids include tannins and anthocyanins. Tannins are responsible for astringency and bitterness, and they provide structure and ageing potential[3]. Anthocyanins, found in grape skins, are the principal pigments responsible for the red and purple colours of many wines.
Non-flavonoids include hydroxycinnamic acids, which influence oxidation reactions, and stilbenes such as resveratrol, which occur in small amounts and have attracted attention for their potential health-related properties[4].
Role in Winemaking
Phenolic compounds influence multiple aspects of wine character. They contribute to colour stability, flavour development, and textural qualities such as dryness and grip. In red winemaking, extended maceration is used to extract phenolics from grape skins and seeds, while in white winemaking, phenolic management often aims to limit excessive bitterness and browning reactions[5]. Oak maturation also adds phenolics such as ellagitannins, further shaping aroma and flavour.
Stability and Transformation
Phenolic compounds undergo significant transformations during fermentation and ageing. Oxidation can lead to browning in white wines and colour loss in reds, while polymerisation of tannins and anthocyanins stabilises colour and softens texture over time[6]. These reactions are central to the capacity of fine wines to develop complexity and harmony with age.
See also
References
- ↑ Jackson, Wine Science: Principles and Applications, 5th ed., Academic Press, 2020.
- ↑ Robinson (ed.), The Oxford Companion to Wine, Oxford University Press, 2015.
- ↑ Boulton, Singleton, Bisson & Kunkee, Principles and Practices of Winemaking, Springer, 1999.
- ↑ Cheynier, Phenolic Compounds in Foods and Natural Health Products, American Chemical Society, 2005.
- ↑ Jackson, Wine Science: Principles and Applications, 5th ed., Academic Press, 2020.
- ↑ Robinson (ed.), The Oxford Companion to Wine, Oxford University Press, 2015.