Skin phenols: substance of the berry skin

The standard

Extractable skin substance measures not the total phenol content but the share that becomes soluble when the skin is ripe. Unripe skins hold their phenols back or release harsh ones.

Criteria

• Colour comes from the anthocyanins, structure from the skin tannins
• Decisive is the soluble share, not the total content
• The ripeness of the skin governs the amount and kind of extraction
• Skin and seed phenols are considered separately

Distinction

Skin phenols ≠ seed tannins: the skin gives colour and softer structure, the seed harder, more bitter tannins. Skin phenols ≠ phenolic ripeness: skin phenols are the substance, phenolic ripeness its condition at picking. Extractable skin substance counts only what a ripe skin yields.