ISO 14502-1-2005 PDF

Full title and description

Determination of substances characteristic of green and black tea — Part 1: Content of total polyphenols in tea — Colorimetric method using Folin‑Ciocalteu reagent. This International Standard specifies a colorimetric assay for measuring total polyphenol content in leaf and instant tea products (green and black teas).

Abstract

ISO 14502-1:2005 defines a procedure using the Folin‑Ciocalteu phenol reagent to determine total polyphenol content in tea. The method covers sample extraction, reaction with the Folin reagent, colour development and photometric measurement, and expression of results (typically as gallic acid equivalents). It is intended for both leaf teas and instant teas. A technical corrigendum (ISO 14502-1:2005/Cor 1:2006) was published to correct minor points in the original text.

General information

• Status: Published; International Standard (confirmed on review cycles).
• Publication date: March 2005 (first published 16 March 2005).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 67.140.10 (Tea).
• Edition / version: Edition 1 — 2005 (with Corrigendum ISO 14502-1:2005/Cor 1:2006).
• Number of pages: 10 pages (main document).

Scope

This standard specifies a colorimetric method using Folin‑Ciocalteu reagent for the determination of total polyphenol content in both green and black teas, including leaf teas and instant tea products. The method describes sample preparation, extraction, reagent reaction and photometric measurement, and gives requirements for calibration, expression of results and reporting. It is intended for routine analytical and quality‑control use where a reliable estimate of total phenolic content is required, while more specific analyte determinations (for example individual catechins) are covered by other parts of the ISO 14502 series.

Key topics and requirements

• Folin‑Ciocalteu colorimetric assay for total polyphenols (principle and reagents).
• Sample preparation and extraction procedures for leaf and instant teas.
• Calibration and expression of results (commonly as gallic acid equivalents).
• Photometric measurement: wavelength, blanking and instrumental conditions.
• Performance characteristics, repeatability and limits of application.
• Instructions for reporting results and relevant uncertainties; notes on method limitations and interferences.

Typical use and users

Used by food and beverage analytical laboratories, tea processing and manufacturing quality‑control teams, regulatory and standards bodies, and research groups studying tea composition or authenticity. Typical applications include routine QC of raw tea and instant products, comparative surveys of polyphenol content, and inputs to nutritional/label data.

Related standards

ISO 14502 is a multipart series; related documents include ISO 14502-2:2005 (HPLC method for determination of catechins in green tea) and the technical corrigendum ISO 14502-1:2005/Cor 1:2006 which corrects the Part 1 text. Other ISO and national standards for tea analysis (sampling, theaflavins, vocabulary and proximate tests) are relevant for a comprehensive testing program.

Keywords

Tea; green tea; black tea; total polyphenols; Folin‑Ciocalteu; colorimetric assay; colorimetry; tea analysis; ISO 14502; quality control; analytical method; gallic acid equivalents; sample extraction.

FAQ

Q: What is this standard?

A: ISO 14502-1:2005 is an International Standard that specifies a colorimetric method (Folin‑Ciocalteu reagent) for determining the total polyphenol content of tea (leaf and instant products).

Q: What does it cover?

A: It covers sample extraction, reaction with Folin‑Ciocalteu reagent, photometric measurement, calibration and reporting of total polyphenol content (expressed typically as gallic acid equivalents), and provides performance and reporting guidance.

Q: Who typically uses it?

A: Food and beverage testing laboratories, tea producers and packers, quality assurance personnel, regulatory testing laboratories and academic researchers studying tea composition or comparing products.

Q: Is it current or superseded?

A: The 2005 edition (with Corrigendum 2006) remains the published version; the standard has been subject to periodic review and was confirmed in recent reviews, so it is considered current (not superseded) as of the latest ISO review cycle information.

Q: Is it part of a series?

A: Yes — ISO 14502 is a multipart series addressing substances characteristic of green and black tea. Part 2 (ISO 14502-2:2005) specifies an HPLC method for catechins; other related ISO tea standards cover different analytes and testing aspects.

Q: What are the key keywords?

A: Tea analysis, total polyphenols, Folin‑Ciocalteu, colorimetric method, gallic acid equivalents, green tea, black tea, ISO 14502.