Abstract:

To facilitate the comprehensive monitoring of milk fat content in dairy products or pipeline residues throughout
the dairy processing, a rapid assay for milk fat based on dual wavelengths of ultraviolet absorption was developed. Milk
fat was recovered from samples of liquid dairy or dairy processing pipe wall with a extraction-precipitation operation and
the absorbance at 204 nm and 230 nm of the milk fat extract was detected. The milk fat content could be calculated with
the standard curve equation from the difference between absorbance at 204 nm and 230 nm. In this way, the interference
of various heat treatments on samples could be avoided. It was verified that the variation coefficients were less than 3%
and the recoveries ranged from 95.6% to 102.9% for liquid dairy samples. In addition, the method led to reliable results in
determining milk fat residues in pipe wall under various dairy processing conditions.

Key words: milk fat, rapid determination, ultraviolet absorption, dual wavelength, heat treatment