Xanthan gum from four Xanthomonas campestris strains authorised in feed: viable cells of the production strains were excluded by plating 1 g (30 °C, 6 days) and MALDI-TOF or PCR identification, specification 4.2–5 % CO₂
Commission Implementing Regulation (EU) 2026/538, published on 12 March 2026, after re-evaluation authorises until 1 April 2036 xanthan gum produced with Xanthomonas campestris ATCC SD 7012, DSM 23730, CNCM I-4861 or CIP 74.23 as a stabiliser and thickener in feed for all animal species except cats, dogs and aquatic species. In its 2021 opinion EFSA could not conclude on the safety of the additive; the opinion of 6 May 2025, based on new data on the strains, closed that question. For dogs at a higher level EFSA will prepare a separate opinion.
- In 2021 the identity of the strains had not been unambiguously established, antimicrobial susceptibility data were incomplete and the presence of viable cells or DNA of the production strains could not be excluded. The additive is made by four companies, each with a different strain; the new data comprised whole-genome sequences screened against antimicrobial resistance gene databases — with no hits of concern — and phenotypic resistance, including to ciprofloxacin, which EFSA considered of no concern in the absence of acquired resistance genes.
- Viable cells: for each strain 3 batches of the additive were tested in triplicate — 1 g of gum was plated (on TSA or on a medium with tetrazolium chloride that helps to recognise X. campestris colonies), incubated at 30 °C for 6 days, with positive controls. Colonies that grew for some of the strains were identified by MALDI-TOF or PCR as not originating from the production strain.
- Specification: the gum as a sodium, potassium or calcium salt; loss on drying ≤ 15 % (105 °C, 2.5 h); ash ≤ 16 % on an anhydrous basis (650 °C, after 4 h drying at 105 °C); pyruvic acid ≥ 1.5 %; nitrogen ≤ 1.5 %; ethanol and propan-2-ol ≤ 500 mg/kg; 4.2–5 % CO₂ on a dry basis, corresponding to 91–108 % xanthan gum. The additive is characterised according to the FAO JECFA monograph referred to in Regulation (EU) No 231/2012.
- Maximum contents in mg/kg complete feed: chickens for fattening and reared, minor poultry species, ornamental birds and other species 56; turkeys for fattening 75; laying poultry 83; Leporidae 88; piglets 100; pigs for fattening 120; dairy and reproductive ruminants 143; sows 146; sheep, goats, ruminants for fattening or rearing and Equidae 220; calves (milk replacers) 233. EFSA could not conclude on eye irritation — eye and respiratory protection is required. Additive and premixtures made under the old rules before 1 October 2026, feed for food-producing animals before 1 April 2027 and other feed before 1 April 2028 may be used until stocks are exhausted.