ISO 23134:2022

INTERNATIONAL ISO
STANDARD 23134
First edition
2022-07
Coffee and coffee products —
Determination of particle size of
ground roasted coffee — Horizontal
sieving motion method using circular
brushes
Café et dérivés du café — Détermination de la taille des grains de café
torréfié moulu — Méthode de tamisage horizontal à l’aide de brosses
circulaires
Reference number
ISO 23134:2022(E)
© ISO 2022

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ISO 23134:2022(E)
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Published in Switzerland
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ISO 23134:2022(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Apparatus . 2
6 Sample preparation .3
6.1 General . 3
6.2 Division of the sample . 3
6.3 Test sample . 3
7 Procedure .3
8 Precision of the method .4
8.1 Interlaboratory test . . 4
8.2 Repeatability . 4
8.3 Reproducibility . 4
9 Test report . 4
Annex A (informative) Precision data of the validation study on the particle sizes of ground
roasted coffee for horizontal sieving motion method using circular brushes .6
Annex B (informative) Reliability of the horizontal sieving method using brushes .7
Annex C (informative) Sieve size . 8
Annex D (informative) Determination of average particle size calculated by mathematical
model .10
Annex E (informative) Specifications and manufacturing of circular brushes .12
Bibliography .16
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ISO 23134:2022(E)
Foreword
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This document was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 15,
Coffee.
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INTERNATIONAL STANDARD ISO 23134:2022(E)
Coffee and coffee products — Determination of particle
size of ground roasted coffee — Horizontal sieving motion
method using circular brushes
1 Scope
This document specifies a method for carrying out particle-size distribution analysis of roasted
ground coffee by horizontal sieving motion method using circular brushes to minimize the effects of
obstruction, agglomeration and adhesion. It specifies general principles to follow concerning apparatus,
procedure and presentation of results.
This document is applicable to particle sizes ranging from approximately 150 μm to 2 mm.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 565, Test sieves — Metal wire cloth, perforated metal plate and electroformed sheet — Nominal sizes
of openings
ISO 2395, Test sieves and test sieving — Vocabulary
ISO 3310-1, Test sieves — Technical requirements and testing — Part 1: Test sieves of metal wire cloth
ISO 9276-1, Representation of results of particle size analysis — Part 1: Graphical representation
ISO 9276-2, Representation of results of particle size analysis — Part 2: Calculation of average particle
sizes/diameters and moments from particle size distributions
ISO 9276-3, Representation of results of particle size analysis — Part 3: Adjustment of an experimental
curve to a reference model
ISO 9276-4, Representation of results of particle size analysis — Part 4: Characterization of a classification
process
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 2395 apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Principle
Separate a sample of roasted ground coffee by horizontal sieving machines using circular brushes on
each test sieve to obtain reliable analysis.
Annex B compares the results of the horizontal sieving method (with or without brushes) to the results
of the laser diffraction method.
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ISO 23134:2022(E)
5 Apparatus
The usual laboratory apparatus and, in particular, the following shall be used.
5.1 Horizontal sieve shaker or tap sieve shaker.
The equipment shall be provided with a timer that counts to at least 10 min, as well as all the necessary
accessories for its proper and safe functioning.
5.2 Test sieves.
The sieves given in Table 1 shall be used in accordance with ISO 565 and ISO 3310-1. It is not necessary
to use sieves smaller than 150 μm (experimental evidence for this is given in Annex C).
Test sieving shall be carried out with a single test sieve or with a series of test sieves with different
nominal aperture sizes. A lid and receiver pan should be included in both cases, where appropriate.
The number of sieves used in the test should be sufficient to give the requisite information about the
material and to avoid excessive wear or blinding.
Table 1 — Sieves’ opening in accordance with ISO 565 and ISO 3310-1
Series R 20/3 Series R 40/3
μm μm
1 400 1 180
1 000 850
710 600
500 425
355 300
250 212
180 150
5.3 Balance, capable of weighing to an accuracy of 0,1 g.
5.4 Special circular brush, with a convex or flat cap and a mass not greater than 25 g in order to
avoid possible fractionation of the material by the brush. For detailed information on the brushes and
their manufacturing, see Annex E.
A special circular brush with a cap is illustrated in Figure 1.
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ISO 23134:2022(E)
Key
a bristle brush diameter: 13 mm to 17 mm
b circular brush diameter: 80 mm to 100 mm
Figure 1 — Special circular brush with a cap
6 Sample preparation
6.1 General
The sampling method used should be such that the sample taken for sieving is truly representative of
sample material from which is has been drawn.
6.2 Division of the sample
The original sample is often too large for direct use in a sieve test: it shall therefore be reduced. In
reducing the sample, it is just as important to ensure that the final quantity (test sample) taken for
sieving is truly representative of the original sample as it is to ensure that the original sample was
representative of the material.
NOTE A precision divider can be used for this purpose.
6.3 Test sample
Take a te
...