ISO/TR 12591:2013

Overview

ISO/TR 12591:2013 provides an internationally agreed definition of white tea based on botanical source and production methods used in international trade. The Technical Report clarifies the plant parts, primary processing stage and sensory expectations that distinguish white tea from green and black teas. It covers manufacture, chemical considerations and practical recommendations for identification and quality assurance.

Key points:

• White tea is derived solely from varieties of Camellia sinensis (L.) O. Kuntze suitable for beverage production.
• Production is characterised by a single withering/drying stage without enzyme inactivation (no steaming or pan-firing) and without rolling or cutting.
• The Report excludes flavoured white tea, blended white tea, and decaffeinated or soluble extracts.

Key Topics

• Plant source and parts used: White tea is produced from buds and tender shoots (one to three leaves). Two main subtypes are noted:

  • Bud-only grades (e.g., "silver needle" / longevity eyebrow) consisting mainly of unopened buds.
  • Bud-plus-leaf grades (e.g., Pai Mu Dan / White Peony) including the bud and first to third leaves.

• Processing stages: White tea undergoes minimal processing - harvested material is laid out to wither and dry (sun, covered, or with heated air). No enzyme inactivation, rolling or comminution is performed.

• Sensory analysis: Skilled tasters can differentiate white from green teas by the absence of sensory notes associated with enzyme inactivation (steam or pan-firing). Assessment covers dry leaf appearance, infused leaf, and liquor appearance, odour and taste.

• Chemical considerations: White and green teas typically have higher catechin levels than black tea; ratios of chemical components (catechins, caffeine, theanine) may assist differentiation. ISO/TR 12591:2013 highlights the need for further chemical data and standardised analysis.

Applications

ISO/TR 12591:2013 is practical for:

• Manufacturers and processors implementing good production practice for white tea.
• Quality assurance teams and laboratory analysts assessing authenticity and compositional attributes.
• Regulatory bodies and purchasers requiring a consistent definition for trade, labelling and inspection.

Practical recommendations include that white tea should be clean, free from taint, free from additives (colourings, flavourings), and show the expected appearance, colour and taste on sensory inspection.

Related Standards

Relevant ISO methods referenced for chemical and sensory work include established ISO analytical techniques for tea composition and sensory analysis. The Report also cites literature on polyphenol/catechin analysis using ISO methods and notes further standardisation needs for wider sample sets and additional chemical markers.

For users seeking to apply the definition: consult ISO/TR 12591:2013 alongside ISO sensory and analytical standards to establish robust identification and quality assurance processes for white tea.