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UDC 633.1.002.6 : 620.1
IS0
I NT ERN AT1 O N A L O RG A N IZ AT1 O N FOR STAN D AR0 IZATl ON
IS0 RECOMMENDATION
R 711
CEREALS AND CEREAL PRODUCTS
DETERMINATION OF MOISTURE CONTENT
(Basic reference method)
1st EDITION
April 1968
COPYRIGHT RESERVED
The copyright of IS0 Recommendations and IS0 Standards
belongs to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized therefore only
by the national standards organization of that country, being
a member of ISO.
For each individual country the only valid standard is the national standard of that country.
Printed in Switzerland
Also issued in French and Russian. Copies to be obtained through the national standards organizations.
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BRIEF HISTORY
The IS0 Recommendation R 7 1 1, Cereals and cereal products - Determination of moisture
content. (Basic reference method), was drawn up by Technical Committee ISO/TC 34, Agricultural
food products, the Secretariat of which is held by the Magyar Szabvanyügyi Hivatal (MSZH).
Work on this question by the Technical Committee began in 1960 and led, in 1965, to the
adoption of a Draft IS0 Recommendation.
In March 1966, this Draft IS0 Recommendation (No. 908) was circulated to all the IS0 Member
Bodies for enquiry. It was approved, subject to a few modifications of an editorial nature, by the
following Member Bodies :
Australia Hungary Romania
Belgium India South Africa,
Bulgaria Iran Rep. of
Colombia Netherlands U.A.R.
Czechoslovakia
New Zealand United Kingdom
Finland Norway U.S.S.R.
France Poland Yugoslavia
Germany Portugal
One Member Body opposed the approval of the Draft :
Chile
The Draft IS0 Recommendation was then submitted by correspondence to the IS0 Council
which decided, in April 1968, to accept it as an IS0 RECOMMENDATION.
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ISOlR 71 1-1968 (E
April 1968
IS0 Recommendation R 711
CEREALS AND CEREAL PRODUCTS
DETERMINATION OF MOISTURE CONTENT
(Basic reference method)
INTRODUCTION
This IS0 Recommendation has been established to serve as the basic reference method with which to
compare routine or other test procedures for the determination of the moisture content of cereals and
cereal products. The method is designed to avoid any chemical alteration in the substance, particularly
oxidation and loss of volatile organic substances, while ensuring complete removal of all moisture
from the product. Tests of reversibility and the addition of moisture indicate that, in the present state
of knowledge, the method may be regarded as enabling the true moisture content of cereals and
cereal products to be obtained.
1. SCOPE
This IS0 Recommendation describes the basic reference method for the determination of water
1.1
in cereals and cereal products.
1.2 Field of application
This method is intended to serve as a standard for checking and perfecting methods which are
particularly suitable for the routine determination of moisture in cereals and cereal products.
It is not intended to be used for settling commercial disputes.
NOTE. ~ For simplicity, in the following sections the term product is used to designate either a cereal or a
cereal product.
2. DEFINITION
The moisture confenf is defined as the loss in mass, expressed as a percentage of the mass of the origi-
nal sample, undergone by the product under the conditions specified in this IS0 Recommendation.
3. PRiNCIPLE
Determination of the loss in mass when the product, if necessary ground without change in moistOre
content, is brought into equilibrium with a dry atmosphere at a temperature between 45 and 50 C,
at a pressure of 13 to 26 mbar (10 to 20 mmHg).
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ISOlR 711-1968 (1
4. APPARATUS
4.1 Analytical balance
4.2 Apparatus for obtaining a pressure of 13 to 26 mbar (IO to 20 mmHg), e.g. a water pump.
4.3 Grinding mill
- made of material which does not absorb moisture,
- easy to clean and having as little dead space as possible,
- enabling grinding to be carried out rapidly and uniformly, without appreciable develop-
ment of heat and, as far as possible, without contact with the outside air,
- adjustable so as to obtain particles of the dimensions indicated in clause 5.1.1.
4.4 Metal dish, non-corrodible, with a sufficiently tight-fitting lid, the effective surface enabling the
test portion to be distributed so as to give not more than 0.3 g/cm2 .*
4.5 Glass or porcelain boat.
4.6 Drying tube**, of glass, of which one part is closed at one end and the other part cames a semi-
capillary tube, with a stopcock, for evacuation purposes. The two parts are connected by a
ground joint.
The test portion may be cooled in this apparatus after drying, a desiccator being then
unnecessary for this operation.
4.7 Constant temperature oven, electrically heated, or any other system enabling the part of the
drying tube containing the dish (4.4) to be brought to a temperature between 45 and 50 OC.
4.8 Air-drying train, gas-washing bottle containing pure analytical-grade sulphuric acid,
pz0 2 1.83 g/ml, connected to a tube containing pure analytical-grade phosphorus pentoxide
spread on glass wool.
4.9 Desiccator, containing an efficient desiccant.
5. PROCEDURE
Carry out weighings to the nearest 0.0002 g.
See Annex A.l for a diagram (for guidance only) of a metal dish.
*
See Annex A.2 for a diagram (for guidance only) of a drying tube.
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ISO/R 711 -1968 (E)
5.1 Preparation of sample
5.1.1 Products not requiring to be ground
Products having particles of sizes below or equal to 1.7 mm, less than 10 by mass being
over 1 mm and more than 50 ok by mass being less than 0.5 mm, do not need to be ground
before the determination.
5.1.2 Products requiring to be ground
If the sample does not comply with the particle size characteristics mentioned above, it req-
uires to be ground either with or without pre-conditioning.
5.1.2.1 GRINDING WITHOUT PRE-CONDITIONING
This applies to products which are not likely to undergo variations in moisture content
in the course of grinding; in general, grains with a moisture content between 7 and 17
Adjust the grinding mill (4.3) to obtain particles of the dimensions indicated in clause
5.1.1, grind a small quantity of the product and reject this.
Then quickly grind about 3.5 g of the sample.
Transfer the grindirigs to the previously dried and tared dish
...