An infrared attenuation measuring system, for the quantitative determination of the concentration of one or more components in an aqueous fat-containing sample, such as milk, by an infrared attenuation technique. The system comprising a set of waveband-related parameters containing information enabling the system to calculate the concentrations substantially independent of the degree of homogenization of the fat-containing sample, and/or to determine the degree of homogenization of the sample. The parameter set contains parameters which are related to wavebands containing a high degree of information about the homogenization degree of the sample. This may be wavebands containing little information about the chemical components of the sample, and/or wavebands containing a substantial amount of information about the chemical components of the sample. The system is calibrated with aqueous fat-containing samples with different degrees of homogenization. The calculating means may be a microprocessor calculating the concentration of the component or components in question, or a neural network defined by the wave band-related parameters. The wavebands in which the attenuation values are determined in the infrared attenuation measuring means may be defined by optical filters, stationary grating and movable and/or multiple detectors, or by movable grating and one or several stationary or movable detectors. The infrared attenuation measuring means may comprise an interferometer, the data obtained from the interferometer being processed using Fourier transformation; and infrared attenuation measuring means of this type may be a FTIR spectrophotometer.
