ISO 3720:2011

Overview

ISO 3720:2011 - "Black tea - Definition and basic requirements" is an international standard that defines what constitutes black tea for beverage use and sets basic chemical, packing and marking requirements. Published by ISO in 2011 (fourth edition), the document applies to tea produced from the tender shoots of Camellia sinensis by conventional black‑tea processes (withering, leaf maceration, aeration and drying). Scented and decaffeinated black teas are excluded.

Key topics and requirements

ISO 3720:2011 focuses on measurable quality and conformity criteria used in quality control, inspection and trade:

• Definition and scope: Black tea must be derived solely from Camellia sinensis and produced by accepted processing steps for black tea.
• Organoleptic requirements: Tea shall have no taint and be reasonably free from extraneous matter; sensory assessment of liquor is performed using ISO 3103 methods and vocabulary from ISO 6078.
• Chemical requirements: The standard specifies chemical limits (expressed on oven‑dried basis) used to indicate good production practice, including:
  • Minimum water extract (e.g., 32% mass fraction)
  • Minimum total polyphenols (e.g., 9% mass fraction)
  • Maximum acid‑insoluble ash (e.g., 1.0% mass fraction)
  • Maximum crude fibre (e.g., 16.5% mass fraction)
  • Requirements for total ash, water‑soluble ash (as % of total ash) and alkalinity of water‑soluble ash (expressed as KOH equivalents)
• Sampling and test methods: Sampling per ISO 1839; sample preparation ISO 1572; and test methods referenced (ISO 9768, ISO 1573/1575/1576/1577/1578, ISO 14502‑1, ISO 15598, etc.).
• Packing and marking: Tea must be packed in clean, dry, closed containers made of non‑reactive materials. Labelling must meet legal requirements and contractual agreements.

Applications and users

ISO 3720 is practical for:

• Tea producers and processors establishing product specifications and in‑house QC
• Laboratory analysts performing compositional testing and conformity checks
• Exporters, importers and trade inspectors using standardized acceptance criteria
• Quality managers and procurement teams drafting contracts and supplier requirements
• Regulatory bodies and standards organizations harmonizing tea definitions and limits

Practical uses include contract specification, acceptance testing, dispute resolution, routine QC and harmonized trade practices for black tea.

Related standards

Normative references within ISO 3720 include:

• ISO 1839 (Sampling), ISO 1572/1573 (sample prep & moisture), ISO 9768 (water extract),
• ISO 1575/1576/1577/1578 (ash determinations), ISO 3103 (sensory liquor prep),
• ISO 14502‑1 (polyphenols), ISO 15598 / ISO 5498 (crude fibre), ISO 6078 (vocabulary).

Keywords: ISO 3720, black tea standard, black tea definition, tea chemical requirements, tea packing and marking, tea sampling, tea quality control.