ISO 939:2021

Spices and condiments - Determination of moisture content

This document specifies an entrainment method for the determination of the moisture content of spices and condiments.

Épices et condiments — Détermination de la teneur en eau

General Information

• Status: Published
• Publication Date: 03-Jan-2021
• ICS: 67.220.10 - Spices and condiments
• Technical Committee: ISO/TC 34/SC 7 - Spices, culinary herbs and condiments
• Drafting Committee: ISO/TC 34/SC 7 - Spices, culinary herbs and condiments
• Current Stage: 6060 - International Standard published
• Start Date: 04-Jan-2021
• Due Date: 31-Oct-2020
• Completion Date: 04-Jan-2021

Relations

• Revises: ISO 939:1980 - Spices and condiments - Determination of moisture content - Entrainment method
• Effective Date: 02-Sep-2017

Overview

ISO 939:2021 specifies an entrainment distillation method for the determination of moisture content in spices and condiments. The method uses an organic solvent immiscible with water (toluene, unless otherwise specified) to entrain water by azeotropic distillation and collect it in a graduated receiver. The standard is intended to provide a repeatable laboratory procedure to support quality control, shelf-life assessment and regulatory compliance.

Key Topics

• Principle: azeotropic/entrainment distillation using an immiscible solvent to extract and measure water.
• Reagent: toluene (saturated with water then distilled; other solvents may be used where specified by product standards).
• Apparatus: short-necked flask (≥500 ml), reflux condenser, receiver with a graduated tube (0–5 ml, 0.1 ml graduations), analytical balance, heat source and a spiral copper wire for aiding separation.
• Sampling & sample prep: sampling by ISO 948 and preparation of a ground sample by ISO 2825 are referenced and required for representative results.
• Test portion: about 40 g (weighed to 0.01 g) so that collected water volume does not exceed 4.5 ml.
• Expression of results: moisture content w (%) = 100 × V / m, where V is volume of collected water (ml) and m is mass of test portion (g).

Procedure (practical steps)

1. Apparatus cleaning: clean with a laboratory-grade detergent, rinse with water and dry thoroughly to avoid adhesion of droplets.
2. Sample preparation: prepare ground test sample per ISO 2825.
3. Weigh test portion: weigh ~40 g to nearest 0.01 g.
4. Charge flask: transfer sample to flask and add ~75 ml toluene to cover the sample; assemble distillation apparatus.
5. Fill receiver: pour toluene through the condenser to fill the receiver; use a calcium chloride tube or cotton plug to avoid atmospheric moisture entering the condenser.
6. Distill: heat to achieve ~100 drops/min; when most water has distilled, increase to ~200 drops/min until no more water is collected. Periodically wash condenser walls with small toluene portions and use the spiral copper wire to coalesce droplets.
7. Equilibration: reflux until the water level in receiver is unchanged for 30 min; then cool/immerse the receiver at room temperature for at least 45 min and read the water volume.

Applications

• Routine quality control of spices and condiments
• Shelf-life and storage condition assessment
• Verification for trade specifications and regulatory testing

Related Standards

• ISO 948 - Spices and condiments: Sampling
• ISO 2825 - Spices and condiments: Preparation of a ground sample for analysis
• ISO 939 Annex A - informative example and detailed illustration of the entrainment distillation apparatus

This guidance highlights practical elements required to implement ISO 939:2021 in laboratory workflows while preserving traceability, repeatability and compliance with referenced sampling/preparation standards.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 939
Second edition
2021-01
Spices and condiments —
Determination of moisture content
Épices et condiments — Détermination de la teneur en eau
Reference number
©
ISO 2021
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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ii © ISO 2021 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents . 1
6 Apparatus . 2
7 Sampling . 2
8 Procedure. 2
8.1 Preparation of apparatus . 2
8.2 Preparation of test sample . 2
8.3 Test portion . 2
8.4 Determination . 2
9 Expression of results . 3
10 Test report . 3
Annex A (informative) Example of entrainment distillation apparatus . 4
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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 7,
Spices, culinary herbs and condiments.
This second edition cancels and replaces the first edition (ISO 939:1980), which has been technically
revised. The main changes compared with the previous edition are as follows:
— the Introduction has been deleted;
— definition 3.1 has been revised;
— in 8.1, “a potassium dichromate sulphuric acid cleaning solution” has been replaced by “a laboratory-
grade detergent”;
— in 8.4, “asbestos cloth” has been replaced by “glass fibres, stone wool or ceramic fibres”;
— in 8.4, the instruction to immerse the receiver in water at room temperature has been changed from
“15 min” to “45 min”;
— in Annex A b), the inner tube diameter has been changed from “9,5 to 12,5 mm” to “5 mm to 12,5 mm”.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2021 – All rights reserved

INTERNATIONAL STANDARD ISO 939:2021(E)
Spices and condiments — Determination of moisture
content
1 Scope
This document specifies an entrainment method for the determination of the moisture content of spices
and condiments.
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, onl
...