The method consists in steam distillation of the acid liberated after enzymatic or acid hydrolysis of the glycosides, followed by determination of the quantity of acid obtained, either by direct titration in the distillate with silver nitrate solution in an ammoniacal medium and in the presence of potassium iodide, or by back titration of an excess of silver nitrate solution with ammonium thiocyanate solution, in a suffiently diluted nitric acid medium and in the presence of iron(III) ions. An annex describes a determination by the mercurimetric method.