ISO 8262-3:1987

The method is applicable especially to those products containing distinct quantities of free fatty acids or those which are not completely soluble in ammonia owing to the presence of lumps or non-milk ingredients, such as custards, porridges, etc. The method is also applicable to fresh cheese types. It consists in digesting of a test portion by boiling with dilute hydrochloric acid, filtrating of the hot digest through a wetted filter paper, extracting of the fat form the dried filter paper using n-hexane or light petroleum, removing of the solvent by distillation or evaporation, and weighing of the substances extracted.