Phenolic coffee tasting is a sensory experience often associated with a defects, appearing as medicinal, plastic, or smoky notes, and is primarily sensed through olfaction (both orthonasal and retronasal) and gustatory receptors (bitterness and astringency). These flavors are caused by phenolic compounds like guaiacol and vinyl guaiacol, which are produced by the thermal degradation of chlorogenic acids during roasting, or through improper fermentation during processing.
Here is how we sense phenolic notes:
1. Olfactory Perception (Aroma/Scent)
- Retronasal Olfaction (Inside the Mouth): This is the primary method of detecting phenolic compounds. As the brewed coffee is consumed, aroma compounds travel from the back of the mouth into the nasal cavity.
- Orthonasal Olfaction (Direct Sniffing): Inhaling the “dry aroma” (ground coffee) or “wet aroma” (brewed) can reveal phenolic compounds, which are described as smoky, spicy, or leathery at lower levels, and medicinal, antiseptic, or plastic at higher levels.
- Specific Compounds: Guaiacol and vinyl guaiacol are responsible for this smoky, spicy, or sometimes burnt odor.
2. Gustatory Perception (Taste and Mouthfeel)
- Bitterness: Phenolic compounds act as key triggers for the T2R family of bitter receptors on the tongue.
- Astringency: Polyphenols bind to salivary proteins, creating a sensation of dryness, puckering, or harshness, which is often mistaken for or accompanies the bitterness.
3. Context of Detection
- Cupping: The standard method to identify these defects is during “cupping,” where the coffee is smelled (dry and wet) and then tasted (slurped) to spray the liquid across the palate.
- Defect Recognition: A,medicinal or,chemical taste, is often a sign of improper fermentation or,poor quality control, particularly in,natural,process coffees.
Summary of Key Indicators
| Attribute | Description |
|---|---|
| Aroma | Smoky, medicinal, plastic, rubbery, leathery, or phenolic |
| Taste | Harsh bitterness, medicinal aftertaste |
| Mouthfeel | High astringency (dryness) |
Phenols in Coffee are a major “defect” in specialty coffee, often arising from excessive microbial activity or,premature,death of the coffee cherry on the tree.