L-cysteine and L-cysteine hydrochlorides

In the current application an authorisation is sought under Article 4(1) for L-cysteine and L-cysteine hydrochlorides, under the category/functional group 3(c) “nutritional additives”/“amino acids, their salts and analogues”, and 2(b) “sensory additives”/”flavouring compounds” according to Annex I of Regulation (EC) No 1831/2003. The authorisation is sought for all animal species.
According to the Applicant, the feed additives (L-cysteine and L-cysteine hydrochlorides) include L-cysteine with a minimum purity of 98.0 % (w/w, based on dry matter) and L-cysteine hydrochloride anhydrous and two products of L-cysteine hydrochloride monohydrate with a minimum purity of 98.5 % each one (w/w, based on dry matter).
The feed additives are intended to be added to feed through premixtures or directly into compound feed (including complementary feed) and water for drinking. The current authorisations specify only the maximum limit of 25 mg L-cysteine / kg compound feed when used as a sensory additive / flavouring compound.
For the determination of cysteine in the feed additives, the Applicant proposed the generic methods described in the respective European Pharmacopoeia monographs. However, in the frame of similar dossiers the EURL previously evaluated and recommended the VDLUFA (4.11.6) or equivalent EN ISO 17180 methods based on ion-exchange chromatography (IEC) coupled to post-column derivatisation and optical (visible – VIS or fluorescence – FLD) detection for the determination of cysteine in feed additives and considers that these recommendations are valid also in the frame of the current evaluation.
For the determination of cysteine in premixtures and compound feed, the Applicant proposed the ring-trial validated European Union (EU) method described in Commission Regulation (EC) No 152/2009 based on ion-exchange chromatography (IEC) coupled to post-column derivatisation and optical (VIS) detection, which is dedicated for the determination of free free (synthetic and natural) and of total (peptide-bound and free) amino acids (cysteine plus cystine) in premixtures and compound feed.
This method was further ring-trial validated for amino acids (including cysteine plus cystine) resulting in the equivalent EN ISO 13903 method, which is listed in the mentioned Regulation.
The following performance characteristics from the two ring-trial validation studies were reported for the determination of total cysteine (plus cystine) in animal feedingstuffs: a relative standard deviation for repeatability (RSD_r) ranging from 1.7 to 4.6 % and a relative standard deviation for reproducibility ranging from 8.8 to 19.0 %. For the determination of cysteine in water, the Applicant applied the above mentioned EU method and presented the corresponding data for the determination of cysteine in water. Furthermore, EURL has previously evaluated and recommended the VDLUFA (4.11.6) method for the determination of cysteine in water and considers that these recommendations are valid also in frame of the current evaluation.
Additionally, the EURL considers the “L-cysteine monohydrochloride monograph” of the Food Chemical Codex (FCC), for the identification of L-cysteine monohydrochloride in the feed additives.
Based on the performance characteristics and available data the EURL recommends for official control: (i) the “L-cysteine monohydrochloride monograph” of the Food Chemical Codex (FCC) for the identification of L-cysteine monohydrochloride in the feed additives; (ii) the VDLUFA (4.11.6) or (equivalent EN ISO 17180) methods based on ion-exchange chromatography coupled with optical (visible or fluorescence) (IEC-VIS/FLD) detection, for the determination of cysteine in the feed additives; (iii) the ring-trial validated EU method (or equivalent EN ISO 13903 method) based on IEC-VIS for the determination of cysteine in premixtures and compound feed (for compound feed only when used as nutritional additives); and iv) the EU method (or equivalent EN ISO 13903 method) based on IEC-VIS or VDLUFA (4.11.6) (or equivalent EN ISO 17180) methods based on IEC-VIS/FLD for the determination of cysteine in water.
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.