The Flavour Wheel

Standardising Flavour Description

In 1979, the PSWR Flavour Wheel provided the Scotch whisky industry with its first standardised vocabulary for flavour description. It established a common language to describe sensory characteristics that had previously relied on individual experience and varied terminology.

The PSWR Flavour Wheel emerged from collaboration between whisky assessors in industry and academia, with Dr. Jim Swan's sensory science expertise contributing to its development. This was a professional instrument designed for distillers, blenders, and quality control specialists who needed to communicate precisely about the compounds that create whisky's character.

The Science Behind the Senses

The PSWR Flavour Wheel used a hierarchical design, with broad categories like "Phenolic" and "Estery" in the centre and specific descriptors like "medicinal" or "pear drop" at the edges. The distinctive feature was the pairing of descriptors with specific chemical compounds at defined concentrations:

• Guaiacol at 27 mg/L for smoky characteristics
• O-cresol at 1.75 mg/L for medicinal notes

Integration with Analytical Methods

The wheel was part of a systematic approach to flavour analysis throughout whisky production. Using GC-Sniff analysis, researchers could smell each separated compound as it emerged from the gas chromatograph, building flavour maps that documented over 280 individual compounds in Scotch whisky.

This approach combined analytical chemistry with sensory evaluation to understand whisky composition and quality.

Adaptation for Consumers

Whisky writer Charles MacLean later adapted the wheel for whisky enthusiasts, creating simplified versions that used accessible language. "Apple" instead of "ethyl hexanoate." "Tropical fruit" instead of technical terminology.

Current consumer flavour wheels derive from the original professional tool, though the underlying science is often not apparent to users.