National foreword

This British Standard is the UK implementation of EN 18198:2026.

Contractual and legal considerations

This publication has been prepared in good faith, however no representation, warranty, assurance or undertaking (express or implied) is or will be made, and no responsibility or liability is or will be accepted by BSI in relation to the adequacy, accuracy, completeness or reasonableness of this publication. All and any such responsibility and liability is expressly disclaimed to the full extent permitted by the law.

This publication is provided as is, and is to be used at the recipient’s own risk.

The recipient is advised to consider seeking professional guidance with respect to its use of this publication.

This publication is not intended to constitute a contract. Users are responsible for its correct application.

Compliance with a British Standard cannot confer immunity from legal obligations.

This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 May 2026.

This European Standard was approved by CEN on 13 April 2026.

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-CENELEC 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-CENELEC Management Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czechia, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and United Kingdom.

European foreword

This document (EN 18198:2026) has been prepared by Technical Committee CEN/TC 454 “Algae and algae products”, the secretariat of which is held by NEN.

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 2026, and conflicting national standards shall be withdrawn at the latest by November 2026.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

This document has been prepared under a standardization request addressed to CEN by the European Commission. The Standing Committee of the EFTA States subsequently approves these requests for its Member States.

Any feedback and questions on this document should be directed to the users’ national standards body. A complete listing of these bodies can be found on the CEN website.

According to the CEN-CENELEC Internal Regulations, the national standards organisations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the United Kingdom.

Introduction

This document has been prepared by the experts of CEN/TC 454 'Algae and algae products'.

The European Committee for Standardization (CEN) was requested by the European Commission (EC) to draft European standards or European standardization deliverables to support the implementation of Article 3 of Directive 2009/28/EC for algae and algae-based products or intermediates.

This request, presented as Mandate M/547, also contributes to the Communication on “Innovating for Sustainable Growth: A Bio economy for Europe”.

The former working group CEN Technical Board Working Group 218 “Algae”, was created in 2016 to develop a work programme as part of this Mandate. The technical committee CEN/TC 454 'Algae and algae products' was established to carry out the work programme that will prepare a series of standards.

The interest in algae and algae-based products or intermediates has increased significantly in Europe as a valuable source including but not limited to, carbohydrates, proteins, lipids, and several pigments. These materials are suitable for use in a wide range of applications from food and feed purposes to other sectors, such as textile, cosmetics, biopolymers, biofuel, fertilizers and biostimulants. Standardization was identified as having an important role in order to promote the use of algae and algae products.

The work of CEN/TC 454 should improve the reliability of the supply chain, thereby improving the confidence of industry and consumers in algae, which include macroalgae, microalgae, cyanobacteria, Labyrinthulomycetes, algae-based products or intermediates and will promote and support commercialisation of the European algae industry.

Determining the nitrogen content of algae and algae products is an important method in the algae industry. It is needed to calculate protein content, biomass gross composition, nutritional value, and also to evaluate mass balances along algae farming.

The goal of this document is to give algae producers and algae products industries recommendations for analytical methods for nitrogen content in compliance with food and feed regulations [1]. This document, based on EN ISO 5983‑1:2005Animal feeding stuffs — Determination of nitrogen content and calculation of crude protein content — Part 1: Kjeldahl method and EN ISO 16634‑2:2016, Food products — Determination of the total nitrogen content by combustion according to the Dumas principle and calculation of the crude protein content — Part 2: Cereals, pulses and milled cereal products, demonstrates the suitability of both methods for the determination of nitrogen in micro- and macroalgae and highlight potential differences between the two methods. This document also provides recommendations for the calculation of protein content and guidance to establish accurate nitrogen to protein conversion factors in conjunction with total amino acid analyses according to EN 18197:2026, Algae and algae products — Determination of the amino acid profile of micro- and macroalgae when required.

1 Scope

This document describes the application of Kjeldahl and Dumas methods for the determination of nitrogen content in algae and their relevant products.

The method was initially tested and evaluated on the algae species Nannochloropsis sp. and Palmaria palmata. The study validated this document for both algae species. This method can also be used for other algae species.

2 Normative references

3 Terms and definitions

4 General

5 Kjeldahl nitrogen content

5.1 Principle

5.2 Reagents and materials

5.3 Apparatus

5.4 Sampling

5.5 Preparation of test sample

5.6 Procedure

5.7 Determination

5.8 Blank test

5.9 Check test

5.10 Calculation of nitrogen content and expression of results

5.11 Precision of Kjeldahl method

6 Dumas total nitrogen content

6.1 Principle

6.2 Reagents

6.3 Apparatus

6.4 Sampling

6.5 Preparation of test sample

6.6 Procedure

6.7 Calculation of total nitrogen content

6.8 Precision of Dumas method

7 Test report

8 Difference between Kjeldahl and Dumas methods

9 Calculation of the crude protein content

10 Calculation of specific nitrogen-to-protein conversion factors

Bibliography