ISO 11050:1993

The principle of the method described is hydrolysis of a test portion with a solution of hydrochloric acid at boiling point, concentration of the insoluble particles at a water/hydrocarbon interface, separation by filtration on a filter paper or membrane, microscopic examination, and counting under reflected light, of the impurities of animal origin (i.e. insects at all stages of their development, insect fragments, mites and their fragments, and rodent hairs and their fragments). Applies to wheat flours, with or without additives and having an ash yield not exceeding 0,63 % (m/m), and durum wheat semolinas.