ISO 6673:2025

Green coffee - Determination of loss in mass at 105 °C

This document specifies a method for the determination of the loss in mass at 105 °C of green coffee. This document is applicable to decaffeinated and non-decaffeinated green coffee as defined in ISO 3509. This method of determining the loss in mass can be considered, by convention, as a method for determining the water content and can be used as such by agreement between the interested parties. This method serves as a reference method for calibrating methods of determining the water content.

Café vert — Détermination de la perte de masse à 105 °C

L'ISO 6673 spécifie une méthode de détermination de la perte de masse du café vert à 105 °C. Elle est applicable aux cafés verts décaféinés et non décaféinés, tels qu'ils sont définis dans l'ISO 3509. La présente méthode de détermination de la perte de masse peut être considérée par convention comme une méthode de détermination de la teneur en eau et peut être utilisée comme telle par accord entre les parties intéressées, mais elle donne des résultats inférieurs, d'environ 1,0 %, à ceux qui sont obtenus avec la méthode spécifiée dans l'ISO 1446 (cette dernière méthode faisant uniquement office de méthode de référence pour l'étalonnage des méthodes de détermination de la teneur en eau).

General Information

• Status: Published
• Publication Date: 24-Nov-2025
• ICS: 67.140.20 - Coffee and coffee substitutes
• Technical Committee: ISO/TC 34/SC 15 - Coffee
• Drafting Committee: ISO/TC 34/SC 15 - Coffee
• Current Stage: 6060 - International Standard published
• Start Date: 25-Nov-2025
• Due Date: 31-Aug-2026
• Completion Date: 25-Nov-2025

Relations

• Revises: ISO 6673:2003 - Green coffee - Determination of loss in mass at 105 degrees C
• Effective Date: 02-Sep-2023

Overview

ISO 6673:2025 - "Green coffee - Determination of loss in mass at 105 °C" defines a reference laboratory method for measuring the loss in mass at 105 °C of green (unroasted) coffee. The procedure is applicable to both decaffeinated and non‑decaffeinated green coffee (as defined in ISO 3509) and, by convention, can be used to determine water content. ISO 6673:2025 is intended as a reference method for calibrating routine moisture-determination methods.

Key topics and technical requirements

• Principle: Heat a test portion at 105 °C ± 1 °C for 16 h ± 0.5 h at atmospheric pressure; measure mass loss (principally water and volatile matter).
• Test portion: Approximately 10 g of green coffee spread in the dish.
• Apparatus:
  • Oven with forced ventilation and calibrated temperature control.
  • Dish with close-fitting lid (aluminium, glass or stainless steel; ≈90 mm diameter, 15–30 mm height).
  • Analytical balance with 0.1 mg resolution.
  • Desiccator with effective desiccant.
• Procedure highlights:
  • Pre‑dry dish and lid at 105 °C, cool in desiccator, weigh.
  • Weigh dish + sample (covered), dry with lid removed, cool, reweigh.
  • Perform three determinations on the same test sample and report the arithmetic mean.
• Result expression:
  • Loss in mass w (%) = (m0 − m1) / (m0 − m) × 100
    • m = mass of dish + lid
    • m0 = mass of dish + sample + lid before drying
    • m1 = mass of dish + sample + lid after drying
• Uncertainty and precision:
  • Uncertainty assessment follows ISO/IEC Guide 98-3 (GUM).
  • Interlaboratory data (14 labs) show repeatability limits roughly 0.11–0.34% and reproducibility limits roughly 0.54–1.19%, depending on sample.

Applications and practical value

• Serves as a reference method for calibrating rapid or automated moisture analyzers used in coffee quality control.
• Used in quality assurance, incoming inspection, export/import testing, research, and method validation where an authoritative water-content measurement is required.
• Useful for establishing contract specifications and ensuring compliance with moisture-related storage and handling requirements (mold risk, weight-based trade).

Who should use ISO 6673:2025

• Coffee testing laboratories and QA/QC teams in green‑bean trading, roasting, and storage facilities.
• Regulatory and standards bodies, research institutions, and equipment manufacturers validating moisture measurement systems.
• Exporters, importers and commodity graders requiring a reproducible reference method.

Related standards

• ISO 3509 - Coffee vocabulary (definitions for decaffeinated/non‑decaffeinated).
• ISO 4072 - Recommended sampling for green coffee in bags.
• ISO/IEC Guide 98-3 (GUM) - Expression of measurement uncertainty.
• ISO 5725 series - Precision of measurement methods (interlaboratory studies).

Standards Content (Sample)

International
Standard
ISO 6673
Third edition
Green coffee — Determination of
2025-11
loss in mass at 105 °C
Café vert — Détermination de la perte de masse à 105 °C
Reference number
© ISO 2025
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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or ISO’s member body in the country of the requester.
ISO copyright office
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Published in Switzerland
ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Apparatus . 1
6 Sampling . 2
7 Procedure . 2
7.1 Preparation of the dish.2
7.2 Test portion .2
7.3 Determination .2
7.4 Number of determinations .3
8 Expression of results . 3
9 Uncertainty . 3
10 Precision . 3
11 Test report . 4
Bibliography . 5

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Foreword
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This document was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 15, Coffee.
This third edition cancels and replaces the second edition (ISO 6673:2003), which has been technically
revised.
The main changes are as follows:
— the number of determinations to be carried out on the same test sample has been changed;
— Clause 9 on uncertainty been added;
— the renumbered Clause 11 for the test report has been updated.
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.

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