L-cystine from genetically modified Escherichia coli DSM 34232 as a flavouring in feed: IEC-VIS/FLD, no strain DNA in PCR, mercury of 0.36–0.42 mg/kg in the first batches reduced below 0.1 mg/kg and a recommended maximum of 25 mg/kg
Commission Implementing Regulation (EU) 2026/402, published on 25 February 2026, authorises until 17 March 2036 L-cystine produced with Escherichia coli DSM 34232 as a flavouring for all animal species. The applicant withdrew the part of the application concerning use as an amino acid, and use in water for drinking was not authorised. No maximum content was set, but the label must state a recommended maximum content of 25 mg/kg complete feed.
- Methods in the annex: qualitative identification according to the Food Chemicals Codex “L-cystine” monograph; quantification of cystine in the additive by ion-exchange chromatography with post-column derivatisation and optical detection (IEC-VIS/FLD); in premixtures IEC-VIS according to Regulation (EC) No 152/2009 or IEC-VIS/FLD. Purity: at least 98.5 % on dry matter — EFSA describes the same applicant specification as 98.5 % on an as-is basis.
- Data from the EFSA opinion (10 batches): L-cystine 98.9–101 %, loss on drying < 0.2 %, specific optical rotation −223° to −221° (specification −225° to −215°). In the first 5 batches mercury was 0.36–0.42 mg/kg; the applicant identified the source, introduced corrective measures, and in the next 5 batches mercury was below 0.1 mg/kg. Endotoxins: < 5 µg/kg at that limit of quantification, but at a lower limit (5 ng/g) one batch gave 27.5 ng/g.
- The production strain derives from E. coli K-12, was genetically modified to increase yield and carries acquired antimicrobial resistance genes. In 3 batches in triplicate neither viable cells (with a positive control) nor strain DNA by PCR were detected; the culture supernatant did not inhibit growth of Bacillus spizizenii ATCC 6633. Stauber-Heubach dusting potential 325–1127 mg/m³, solubility 0.122 g/L at 20 °C.
- EFSA considered the additive safe for all species at 25 mg/kg feed and, for users, not a skin or eye irritant nor a skin sensitiser. If the dose on the premixture label would lead to exceeding 25 mg/kg, the premixture label must state the functional group, identification number 2b392, name and added amount. The additive is incorporated into feed via a premixture.