L-tryptophan - 3c440i

In the current application an authorisation is sought under Article 4(1) for L-tryptophan produced by fermentation with Escherichia coli KCCM 80210 (W008), under the category/functional group 3(c) 'nutritional additives'/'amino acids, their salts and analogues', according to Annex I of Regulation (EC) No 1831/2003. The authorisation is sought for all animal species. 

According to the Applicant, the feed additive contains L-tryptophan with a minimum purity of 98 % (w/w). The feed additive is intended to be mixed either in premixtures or added directly to feedingstuffs. However, the Applicant did not propose a minimum or maximum L-tryptophan content in feedingstuffs.

For the determination of tryptophan in the feed additive and premixtures the Applicant submitted the ring-trial validated EN ISO 13904:2016 method based on high performance liquid chromatography with fluorescence detection (HPLC-FLD). The method is dedicated for the determination of free tryptophan in commercial products and premixtures (containing more than 2 % (w/w) of tryptophan) and for the determination of free and total tryptophan in feedingstuffs.

For the determination of tryptophan in feedingstuffs the Applicant submitted a ring-trial validated European Union (EU) method, where the procedure to determine tryptophan in feedingstuffs is identical to the one described in the above mentioned EN ISO 13904:2016 method. The EU method is applicable for the determination of free (synthetic and natural) and total (peptide-bound and free) amino acid using an HPLC method with fluorescence detection (FLD). The method does not distinguish between the amino acid enantiomers. 

Based on the performance characteristics available, the EURL recommends for official control the above mentioned two ring-trial validated methods based on HPLC-FLD to determine tryptophan in the feed additive, premixtures and/or feedingstuffs. 

In addition, for the identification of the feed additive the EURL recommends the "L-tryptophan monograph" of the Food Chemical Codex (FCC), where different tests (including one based on optical rotation) are described. 

Further testing or validation of the methods to be performed through the consortium of National Reference Laboratories as specified by Article 10 (Commission Regulation (EC) No 378/2005, as last amended by Regulation (EU) 2015/1761) is not considered necessary.

Recommended Method

as of:

- Commission Implementing Regulation (EU) 2021/2076

For the identification of L-tryptophan in the feed additive:

Food Chemical Codex ‘L-tryptophan monograph’.

For the determination of tryptophan in the feed additive and premixtures:

High performance liquid chromatography with fluorescence detection (HPLC-FLD) – EN ISO 13904

For the determination of tryptophan in compound feed and feed materials:

High performance liquid chromatography with fluorescence detection (HPLC-FLD); Commission Regulation (EC) No 152/2009(3)(Annex III, G)