ANNEX XIIU.K.
Requirements for urease(Article 19 of this Regulation)U.K.
1.International code for urease: EC 3-5-1-5, CAS No 9002-13-5.U.K.
2.Activity: urease activity (active at acidic pH), to break down urea into ammonia and carbon dioxide. The stated activity is not less than 5 units/mg, one unit being defined as the amount that produces one μmol of ammonia per minute at 37 °C from 5 g/l urea at pH 4.U.K.
3.Origin: Lactobacillus fermentum.U.K.
4.Area of application: breaking down urea present in wine intended for prolonged ageing, where its initial urea concentration is higher than 1 mg/l.U.K.
5.Maximum quantity to be used: 75 mg of enzyme preparation per litre of wine treated, not exceeding 375 units of urease per litre of wine. After treatment, all residual enzyme activity must be eliminated by filtering the wine (pore size < 1 μm).U.K.
6.Chemical and microbiological purity specificationsU.K.
| Loss on drying | Less than 10 % |
| Heavy metals | Less than 30 ppm |
| Lead | Less than 10 ppm |
| Arsenic | Less than 2 ppm |
| Total coliforms | Absent |
| Salmonella spp | Absent in 25 g sample |
| Aerobic count | Less than 5 × 104 cells/g |
Urease used in the treatment of wine must be prepared under similar conditions to those for urease as covered by the opinion of the Scientific Committee for Food of 10 December 1998.