This International Standard describes the operating conditions for instruments used for the determination of fat, protein and lactose content of ex-farm milk, based upon the measurement of the absorption of mid-infrared radiation at wavelengths which are representative of each component analysed.

Any model of instrument which does not comply with the principle of analysis given in this International Standard or which incorporates modifications that may alter the principal characteristics of the apparatus (repeatability, accuracy, conditions of use), as well as the means of adjusting the calibration, will require a separate specific standard.

The method described is applicable to the determination of the fat, protein and, as appropriate, lactose content of ex-farm milk. The method is also applicable to the analysis of milk of other species (goat, ewe, buffalo, etc.) and processed milk provided a specific calibration of the instrument (see clause 7) is made.