SIST EN ISO 27971:2008
(Main)Cereals and cereal products - Common wheat (Triticum aestivum L.) - Determination of alveograph properties of dough at constant hydration from commercial or test flours and test milling methodology (ISO 27971:2008)
Cereals and cereal products - Common wheat (Triticum aestivum L.) - Determination of alveograph properties of dough at constant hydration from commercial or test flours and test milling methodology (ISO 27971:2008)
This International Standard specifies a method of using an alveograph to determine the rheological properties of different types of dough obtained from "soft" to "hard" wheat flour (Triticum aestivum L.) produced by industrial milling or laboratory test milling. It describes the alveograph test and how to use a laboratory mill to produce flour in two stages: Stage 1: preparation of the wheat grain for milling to make it easier to separate the bran from the endosperm (see Clause 7); Stage 2: the milling process itself, including the break system involving three fluted rollers, reduction of particle size between two smooth rollers and the use of a centrifugal sieving machine to grade the products (see Clause 8).
Getreide und Getreideerzeugnisse - Weizen (Triticum aestivum L.) - Bestimmung der Eigenschaften von Teig bei konstanter Flüssigkeitszufuhr zu handelsüblichen Mehlen oder Versuchsmehlen bei gleichen Versuchsmahlverfahren mittels Alveograph (ISO 27971:2008)
Diese Internationale Norm legt ein Verfahren der Anwendung eines Alveographen zur Bestimmung der rheologischen Eigenschaften verschiedener Teigarten fest, die aus „Weich“- bis „Hart“-Weizenmehl (Triticum aestivum L.) erhalten wurden, das durch industrielles Vermahlen oder Vermahlen im Laborversuch hergestellt wurde.
Es beschreibt den Versuch unter Anwendung eines Alveographen und die Art und Weise der Anwendung einer Labormühle zur Mehlherstellung in zwei Stufen:
Stufe 1: Vorbereitung des Weizens zum Vermahlen, damit die Kleie leichter vom Endosperm ge¬trennt werden kann (siehe Abschnitt 7);
Stufe 2: die Vermahlung selbst, die ein Schrotungssystem mit drei Riffelwalzen, die Verrin¬gerung der Korngröße zwischen zwei Glattwalzen und die Verwendung einer Zentrifugalsieb¬maschine zur Klassierung der Erzeugnisse umfasst (siehe Abschnitt 8).
Céréales et produits céréaliers - Blé tendre (Triticum aestivum L.) - Détermination des propriétés alvéographiques d'une pâte à hydratation constante de farine industrielle ou d'essai et méthodologie pour la mouture d'essai (ISO 27971:2008)
L'ISO 27971:2008 spécifie une méthode de détermination, au moyen d'un alvéographe, des caractéristiques rhéologiques de différents types de pâtes obtenues à partir de farines de blés tendres «soft» à «hard» (Triticum aestivum L.) issues de mouture industrielle ou de mouture d'essai en laboratoire.
Elle décrit l'essai à l'alvéographe et les conditions d'obtention de la farine au moyen d'un moulin de laboratoire en deux étapes: 1) préparation des grains de blé en vue de la mouture, afin de faciliter la séparation du son et de l'amande, et 2) processus de mouture comprenant un broyage entre trois cylindres cannelés, une réduction de la taille des particules entre deux cylindres lisses et le classement des produits à l'aide d'une bluterie centrifuge.
Žito in proizvodi iz žita - Skupna pšenica (Triticum aestivum L.) - Določevanje lastnosti testa iz običajnih komercialnih ali preskusnih mok z alveografom ob stalni hidraciji in s preskusnim postopkom mletja (ISO 27971:2008)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 27971:2008
01-september-2008
äLWRLQSURL]YRGLL]åLWD6NXSQDSãHQLFD 7ULWLFXPDHVWLYXP/ 'RORþHYDQMH
ODVWQRVWLWHVWDL]RELþDMQLKNRPHUFLDOQLKDOLSUHVNXVQLKPRN]DOYHRJUDIRPRE
VWDOQLKLGUDFLMLLQVSUHVNXVQLPSRVWRSNRPPOHWMD ,62
Cereals and cereal products - Common wheat (Triticum aestivum L.) - Determination of
alveograph properties of dough at constant hydration from commercial or test flours and
test milling methodology (ISO 27971:2008)
Getreide und Getreideerzeugnisse - Weizen (Triticum aestivum L.) - Bestimmung der
Eigenschaften von Teig bei konstanter Flüssigkeitszufuhr zu handelsüblichen Mehlen
oder Versuchsmehlen bei gleichen Versuchsmahlverfahren mittels Alveograph (ISO
27971:2008)
Céréales et produits céréaliers - Blé tendre (Triticum aestivum L.) - Détermination des
propriétés alvéographiques d'une pâte à hydratation constante de farine industrielle ou
d'essai et méthodologie pour la mouture d'essai (ISO 27971:2008)
Ta slovenski standard je istoveten z: EN ISO 27971:2008
ICS:
67.060 äLWDVWURþQLFHLQSURL]YRGLL] Cereals, pulses and derived
QMLK products
SIST EN ISO 27971:2008 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 27971:2008
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SIST EN ISO 27971:2008
EUROPEAN STANDARD
EN ISO 27971
NORME EUROPÉENNE
EUROPÄISCHE NORM
May 2008
ICS 67.060
English Version
Cereals and cereal products - Common wheat (Triticum
aestivum L.) - Determination of alveograph properties of dough
at constant hydration from commercial or test flours and test
milling methodology (ISO 27971:2008)
Céréales et produits céréaliers - Blé tendre (Triticum Getreide und Getreideerzeugnisse - Weizen (Triticum
aestivum L.) - Détermination des propriétés aestivum L.) - Bestimmung der Eigenschaften von Teig bei
alvéographiques d'une pâte à hydratation constante de konstanter Flüssigkeitszufuhr zu handelsüblichen Mehlen
farine industrielle ou d'essai et méthodologie pour la oder Versuchsmehlen bei gleichen Versuchsmahlverfahren
mouture d'essai (ISO 27971:2008) mittels Alveograph (ISO 27971:2008)
This European Standard was approved by CEN on 4 February 2008.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as the
official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2008 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 27971:2008: E
worldwide for CEN national Members.
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SIST EN ISO 27971:2008
EN ISO 27971:2008 (E)
Contents Page
Foreword.3
2
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SIST EN ISO 27971:2008
EN ISO 27971:2008 (E)
Foreword
This document (EN ISO 27971:2008) has been prepared by Technical Committee CEN/TC 338 "Cereal and
cereal products", the secretariat of which is held by AFNOR, in collaboration with Technical Committee
ISO/TC 34 "Agricultural food products".
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by November 2008, and conflicting national standards shall be withdrawn
at the latest by November 2008.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
3
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SIST EN ISO 27971:2008
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SIST EN ISO 27971:2008
INTERNATIONAL ISO
STANDARD 27971
First edition
2008-05-15
Cereals and cereal products — Common
wheat (Triticum aestivum L.) —
Determination of alveograph properties
of dough at constant hydration from
commercial or test flours and test milling
methodology
Céréales et produits céréaliers — Blé tendre (Triticum aestivum L.) —
Détermination des propriétés alvéographiques d'une pâte à hydratation
constante de farine industrielle ou d'essai et méthodologie pour la
mouture d'essai
Reference number
ISO 27971:2008(E)
©
ISO 2008
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SIST EN ISO 27971:2008
ISO 27971:2008(E)
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ii © ISO 2008 – All rights reserved
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SIST EN ISO 27971:2008
ISO 27971:2008(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Principle. 1
4 Reagents. 2
5 Apparatus . 2
6 Sampling. 3
7 Preparation of the wheat for test milling. 3
7.1 Cleaning the laboratory sample . 3
7.2 Test portion . 7
7.3 Wheat moisture content determination. 7
7.4 Wheat conditioning. 7
8 Laboratory milling. 10
8.1 General. 10
8.2 Milling procedure. 10
8.3 Expression of milling results. 11
9 Preparation and alveograph test. 12
9.1 Preliminary checks . 12
9.2 Preliminary operations. 12
9.3 Kneading. 14
9.4 Preparation of dough test pieces. 16
9.5 Alveograph test. 18
9.6 Expression of the results of the alveograph test . 20
10 Precision. 22
10.1 Interlaboratory tests . 22
10.2 Repeatability limits . 22
10.3 Reproducibility limits . 23
10.4 Uncertainty . 24
11 Test report . 25
Annex A (informative) Characteristics of the Chopin-Dubois CD1 mill. 26
Annex B (normative) Quantity of water to be added to wheat for conditioning. 28
Annex C (informative) Sample milling sheet . 30
Annex D (informative) Conversion table for L to G . 32
Annex E (informative) Interlaboratory data for commercial flour. 34
Annex F (informative) Interlaboratory data for laboratory milled flour. 37
Annex G (informative) Routine maintenance instructions for the alveograph . 48
Annex H (informative) Assessment of proteolytic activity assessment in wheat or flour
(T. aestivum L.). 50
Bibliography . 52
© ISO 2008 – All rights reserved iii
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SIST EN ISO 27971:2008
ISO 27971:2008(E)
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
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
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
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
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
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 27971 was prepared by the European Committee for Standardization (CEN) Technical Committee
CEN/TC 338, Cereal and cereal products, in collaboration with Technical Committee ISO/TC 34, Food
products, Subcommittee SC 4, Cereals and pulses, in accordance with the Agreement on technical
cooperation between ISO and CEN (Vienna Agreement).
This first edition of ISO 27971 cancels and replaces ISO 5530-4:2002, which has been technically revised to
specify the preparation of a test flour, to present complete precision data, and to add one annex giving
alveograph maintenance advice and another for the assessment of proteolytic activity in wheat or flour.
iv © ISO 2008 – All rights reserved
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SIST EN ISO 27971:2008
ISO 27971:2008(E)
Introduction
The end-use value of wheat is determined by a number of properties that are useful in the manufacture of
baked products such as bread, rusks, and biscuits.
Such properties include the important viscoelastic (rheological) properties of dough formed as a result of flour
hydration and kneading. An alveograph is used to study the main parameters by subjecting a dough test piece
to biaxial extension (producing a dough bubble) by inflating it with air which is similar to the deformation to
which it is subjected during panary fermentation.
Recording the pressure generated inside the bubble throughout the deformation of the dough test piece until
rupture provides information on:
⎯ the resistance of the dough to deformation, or its strength (stiffness). It is expressed by the maximum
pressure parameter, P;
⎯ the extensibility or the possibility of inflating the dough to form a bubble. It is expressed by the
parameters of extensibility, L, or swelling, G;
⎯ the elasticity of the dough during biaxial extension. It is expressed by the elasticity index, I ;
e
⎯ the energy required to deform the dough bubble until it bursts, which is proportional to the area of the
alveogram (sum of the pressures throughout the deformation process). It is expressed by the
parameter, W.
The P/L ratio is a measurement of the balance between tenacity and extensibility.
Alveographs are commonly used throughout the wheat and flour industry, for the following purposes:
⎯ selecting and assessing different varieties of wheat and marketing batches of wheat;
⎯ blending different batches of wheat or flour to produce a batch with given values for the alveographic
criteria (W, P, and L) complying with the proportional laws of blending.
Alveographs are used both on the upstream side of the industry for marketing, selecting and assessing the
different varieties and on the downstream side throughout the baking industries (see Bibliography).
© ISO 2008 – All rights reserved v
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SIST EN ISO 27971:2008
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SIST EN ISO 27971:2008
INTERNATIONAL STANDARD ISO 27971:2008(E)
Cereals and cereal products — Common wheat (Triticum
aestivum L.) — Determination of alveograph properties
of dough at constant hydration from commercial or test flours
and test milling methodology
1 Scope
This International Standard specifies a method of using an alveograph to determine the rheological properties
of different types of dough obtained from “soft” to “hard” wheat flour (Triticum aestivum L.) produced by
industrial milling or laboratory test milling.
It describes the alveograph test and how to use a laboratory mill to produce flour in two stages:
Stage 1: preparation of the wheat grain for milling to make it easier to separate the bran from the
endosperm (see Clause 7);
Stage 2: the milling process itself, including the break system involving three fluted rollers, reduction of
particle size between two smooth rollers and the use of a centrifugal sieving machine to grade
the products (see Clause 8).
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 385, Laboratory glassware — Burettes
ISO 660, Animal and vegetable fats and oils — Determination of acid value and acidity
ISO 712, Cereals and cereal products — Determination of moisture content — Routine reference method
ISO 835, Laboratory glassware — Graduated pipettes
ISO 1042, Laboratory glassware — One-mark volumetric flasks
ISO 7700-1, Check of the calibration of moisture meters — Part 1: Moisture meters for cereals
3 Principle
The behaviour of dough obtained from a mixture of different types of flour and salt water is evaluated during
deformation. A dough disk is subjected to a constant air flow; which at first it withstands. Subsequently, it
swells into a bubble, according to its extensibility, and ruptures. The change in the dough is measured and
recorded in the form of a curve called an alveogram.
© ISO 2008 – All rights reserved 1
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SIST EN ISO 27971:2008
ISO 27971:2008(E)
4 Reagents
Unless otherwise specified, use only reagents of recognized analytical grade, and only distilled or
demineralized water or water of equivalent purity.
4.1 Sodium chloride solution, obtained by dissolving (25 ± 0,2) g of NaCl in water and then making the
volume up to 1 000 ml. This solution shall not be stored for more than 15 days and its temperature shall be
(20 ± 2) °C when used.
4.2 Refined vegetable oil, low in polyunsaturates, such as peanut oil. It is possible to use olive oil if its acid
index value is less than 0,4 (determined according to ISO 660). Store in a dark place in a closed container and
replace regularly (at least every 3 months).
Alternatively, liquid paraffin (also known as “soft petroleum paraffin”), with an acid index value less than or
equal to 0,05 and the lowest possible viscosity [maximum 60 mPa s (60 cP) at 20 °C].
1)
4.3 Cold degreasing agent, optimum safety .
5 Apparatus
Usual laboratory apparatus, and in particular the following.
5.1 Mechanical cleaner, fitted with sieves for wheat cleaning, in accordance with the manufacturer's
requirements.
5.2 Conical or riffle sample divider.
5.3 Analytical balance, accurate to 0,01 g.
5.4 Glass burette, of capacity 50 ml, complying with the requirements of ISO 385, Class A, graduated in
0,1 ml divisions, stand-mounted.
2)
5.5 Rotary blender , for grain conditioning and flour homogenization, including the following components:
5.5.1 Constant speed stirrer.
5.5.2 Two worm screws integral with the flask, possibly via the stopper (one for wheat preparation, the
other for flour homogenization).
5.5.3 Several wide-necked plastic flasks, of capacity 2 l.
3)
5.6 Test mill (laboratory mill) manually operated (see Annex A).
1) ITECMA “Securclean ER” is an example of a suitable product available commercially. This information is given for the
convenience of users of this International Standard and does not constitute an endorsement by ISO of this product.
2) The Chopin MR 2 l rotary blender is an example of a suitable product available commercially. This information is given
for the convenience of users of this International Standard and does not constitute an endorsement by ISO of this product.
3) The Chopin-Dubois CD1 test mill is an example of a suitable product available commercially. This information is given
for the convenience of users of this International Standard and does not constitute an endorsement by ISO of this product.
2 © ISO 2008 – All rights reserved
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SIST EN ISO 27971:2008
ISO 27971:2008(E)
5.7 Complete alveograph system (see Table 1 for specifications and characteristics of the accessories)
including the following devices:
5.7.1 Kneading machine [for models MA 82, MA 87 and MA 95, see Figure 1a); for model NG, see labels
a in Figure 2 and Figure 3], with accurate temperature control, for dough sample preparation.
4)
5.7.2 Hydraulic manometer or Alveolink [for models MA 82, MA 87 and MA 95, see Figure 1 b); for
model NG, see labels b in Figure 2 and Figure 3] for recording the pressure curve.
5)
5.7.3 Alveograph [for models MA 82, MA 87 and MA 95, see Figure 1 c); for model NG, see labels c in
Figures 2 and Figure 3] with accurate temperature control, for test piece biaxial deformation of the dough
pieces. It has two rest chambers, each containing five plates on which the dough test pieces can be arranged
prior to deformation.
5.8 Burette, supplied with the apparatus, of capacity 160 ml, graduated in divisions of 0,1 % of moisture
6)
content .
5.9 Timer, for use with model MA 82 only.
5.10 Planimetric scales, supplied with the apparatus where an Alveolink is not included.
5.11 System for recording the test environment conditions (temperature and relative air humidity) as
specified in 8.1 and 9.1.
5.12 Volumetric flask, of capacity 1 000 ml, complying with the requirements of ISO 1042, class A.
5.13 Pipette, of capacity 25 ml, graduated in divisions of 0,1 ml, complying with the requirements of ISO 835,
class A.
6 Sampling
A representative wheat or flour sample should have been sent to the laboratory. It shall not have been
damaged or changed during transport or storage.
Sampling is not part of the method specified in this International Standard. Recommended sampling methods
[1] [6] [7]
are given in ISO 2170 , ISO 6644 , and ISO 13690 .
7 Preparation of the wheat for test milling
7.1 Cleaning the laboratory sample
Pass the laboratory sample through a mechanical cleaner (5.1) to ensure that all stones and metal fragments
are removed and to avoid damaging the rollers during milling. A magnetic device can also be used to remove
ferrous metal fragments.
4) Example of a suitable product available commercially. This information is given for the convenience of users of this
International Standard and does not constitute an endorsement by ISO of this product.
5) The methods specified in this International Standard are based on the use of the MA 82, MA 87, MA 95 and NG
models of Chopin alveograph.
[8]
6) Throughout this International Standard, “content” is to be understood as a “mass fraction” (see ISO 80000-9:— , 12),
i.e. the ratio of the mass of substance in a mixture to the mass of the mixture.
© ISO 2008 – All rights reserved 3
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SIST EN ISO 27971:2008
ISO 27971:2008(E)
a) kneading machine
Key
b) manometer
1 handle A in position 2
2 pump potentiometer
3 micrometric valve for air flow adjustment
c) alveograph
Figure 1 — Alveograph model MA 82, MA 87 and MA 95 assemblies
4 © ISO 2008 – All rights reserved
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SIST EN ISO 27971:2008
ISO 27971:2008(E)
Key
1 micrometric valve for air flow adjustment
a
kneading machine
b
integrator-recorder
c
alveograph (with Alveolink integrator-recorder)
Figure 2 — Alveograph model NG assembly with an Alveolink integrator-recorder
© ISO 2008 – All rights reserved 5
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SIST EN ISO 27971:2008
ISO 27971:2008(E)
Key
1 micrometric valve for air flow adjustment
a
kneading machine
b
recording manometer
c
alveograph (with hydraulic recording manometer)
Figure 3 — Alveograph model NG assembly with a hydraulic recording manometer
6 © ISO 2008 – All rights reserved
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SIST EN ISO 27971:2008
ISO 27971:2008(E)
Table 1 — Specifications and characteristics of the accessories required for the test
Value and
Quantity
tolerance
Rotational frequency of the kneading machine blade
(60 ± 2) Hz
Height of sheeting guides
(12,0 ± 0,1) mm
Large diameter of the sheeting roller
(40,0 ± 0,1) mm
Small diameter of the sheeting roller
(33,3 ± 0,1) mm
Inside diameter of the dough cutter
(46,0 ± 0,5) mm
Diameter of the aperture created when the moving plate opens (which determines the effective
(55,0 ± 0,1) mm
diameter of the test piece)
Theoretical distance between the fixed and moving plates after clamping (equal to the thickness of
(2,67 ± 0,01) mm
the test piece before inflation)
a
Volume of air automatically injected to detach the test piece prior to inflating the bubble (18 ± 2) ml
Linear speed of the periphery of the recording drum (5,5 ± 0,1) mm/s
b
Air flow ensuring inflation (96 ± 2) l/h
Rotation of the manometer drum (from stop to stop)
(55 ± 1) s
a
Some older devices are fitted with a pear-shaped rubber bulb for manual injection of the 18 ml required to detach the test piece.
b
To adjust the flow rate of the air generator used to inflate the bubble, fit the nozzle (Figure 4) to create a specified pressure drop
(and obtain a pressure corresponding to a height of 92 mmHg (12,3 kPa) on the manometer chart). The air flow rate is set with the
standardized pressure drop to obtain a pressure corresponding to a height of 60 mmHg (8,0 kPa) on the manometer chart, i.e.
(96 ± 2) l/h (see Figure 4 and Figure 5).
7.2 Test portion
The test portion shall be representative of the initial wheat mass. Use the sample divider (5.2) to homogenize
and divide the laboratory sample until the mass required for test milling plus moisture content determination is
obtained. The minimum wheat mass of the test portion for milling shall be 800 g.
7.3 Wheat moisture content determination
Determine the moisture content of the test portion as specified in ISO 712, or using a rapid device whose
measurement does not differ from the reference value by ± 0,4 g water per 100 g of sample (see ISO 7700-1).
7.4 Wheat conditioning
7.4.1 General
Conditioning the wheat for milling makes it easier to separate the bran from the endosperm. The target
moisture content is (16 ± 0,5) %.
7.4.2 Wheat with initial moisture content between 13 % and 15 % (one-stage moistening)
Weigh, using the balance (5.3), a test portion of (800 ± 1) g of wheat and pour it into the blender.
Add the required amount of water (see Table B.1) to the grain from the burette (5.4) directly, or after weighing
it to the nearest 0,1 g.
Immediately after adding the water, insert the stopper fitted with the worm screw provided for use with wheat
into the flask, shake vigorously for a few seconds and place on the rotary blender (5.5).
Run the rotary blender for (30 ± 5) min (time required to distribute the water evenly across the surface of the
grains).
© ISO 2008 – All rights reserved 7
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SIST EN ISO 27971:2008
ISO 27971:2008(E)
Key
1 knurled ring
2 nozzle
3 nozzle holder
4
...
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