ISO 11286:2004

INTERNATIONAL ISO
STANDARD 11286
Second edition
2004-02-15
Tea — Classification of grades by particle
size analysis
Thé — Classification par catégories par analyse granulométrique

Reference number
©
ISO 2004
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ii © ISO 2004 – All rights reserved

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
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International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
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International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
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ISO 11286 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 8, Tea.
This second edition cancels and replaces the first edition (ISO 11286:1997), of which it constitutes a minor
revision. The Scope has been modified to exclude large leafy grades of tea.
Introduction
For many years the tea trade has used various systems for the grading nomenclature of teas according to the
sieves used for sorting the teas. However, a designation given in one country does not always have the same
meaning in another and it was considered by some countries, in particular tea-producing countries, that a
single, international method of classifying tea grades according to their particle size distributions would
facilitate international trade.
The method given in this International Standard provides such a system to supplement the existing traditional
systems.
iv © ISO 2004 – All rights reserved

INTERNATIONAL STANDARD ISO 11286:2004(E)

Tea — Classification of grades by particle size analysis
1 Scope
This International Standard specifies a method for the classification of grades of tea according to an analysis
of their particle size. It is not applicable to large, leafy grades of tea.
This method may not be suitable for blends of tea.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 3310-1:1990, Test sieves — Technical requirements and testing — Part 1: Test sieves of metal wire cloth
3 Principle
The tea is separated into different size fractions using a series of sieves on a shaker. The tea particles
retained on each sieve are weighed and the percentage by mass retained on each sieve is calculated.
4 Apparatus
Usual laboratory appara
...