Interference of lipid with determination of bovine serum albumin by electroimmunodiffusion.

Electroimmunodiffusion of ultra-high-temperature processed milk demonstrated an apparent increase in bovine serum albumin at some processing temperatures. The cause of the phenomenon was traced to the lipid component of the milk. Caproic acid was used in model studies to evaluate lipid effects in unheated and heated systems. Addition of caproic acid to bovine serum albumin without heat treatment reduced the apparent concentration of bovine serum albumin. Heating at 78 degrees C resulted in an initial increase in the apparent bovine serum albumin concentration, followed by a decrease with further heating. These results indicate that the reaction of specific antibody with bovine serum albumin in milk is inhibited by lipid and that this inhibition is reversed by heat treatments below that causing marked conformational changes in the protein.