ISO 5506:1988

The method allows inadequate cookingof the products to be detected. It applies to products having a urease activity of less than 1 mg of nitrogen per gram of product as received. For more active products the mass of test may be reduced. The principle consists in mixing of a ground test portion with a buffered urea solution, after keeping the mixture for 30 min at 30 C, neutralization of the ammonia liberated, with an exess of hydrochloric acid solution, and back-titration with standard volumetric hydroxide solution.