Patent ID: 7132660

Claim:
A method of quantitative measurement of fat in a liquid sample by an infrared attenuation technique, wherein the fat is present in the form of an emulsion of particles causing Christiansen's effect, i.e. the combined effect of lightscattering and anomalous dispersion, the method comprising transmitting infrared radiation through the sample, determining the infrared absorption of the sample in at least one measurement waveband exhibiting Christiansen's effect, located in the region of 5.7 μm, or at 3.5 μm or both, with a bandwidth of about 0.010–0.200 μm and with reference to a reference waveband, such that the sample waveband has an effective waveband, which is off-set or displaced from the absorbance peak for homogenized milk, where unhomogenized milks have higher absorbance than homogenized milks and selecting the reference waveband where unhomogenized milks have higher absorbance than homogenized milks, whereby the fat determination is essentially independent of Christiansen's effect.