High-resolution optical low-coherence reflectometry is applied to monitor biological samples. It has been found that the
reflectivity of aged cow's milk is significantly lower than that of the fresh milk with a difference of 5.35dB. During the
process of heating the fresh milk at a constant temperature of 80°C, the reflectivity of the milk gradually decreases with
the increase of the heating duration. The technique is proved to be effective in monitoring the change in the refractive
index of the sample.