Determination of fat in formalin preserved milk samples

Abstract

the following study assessed whether treatment of formaldehyde-preserved composite raw buffalo and cow milk samples with proteolytic enyzmes (Rennin, Nutrase, Trypsin and Pronase) before the Gerber or Rose-Gottlieb test would facilitate fat separation and consequently result in the accurate estimation of fat. Both the Gerber test and Rose-Gottlieb method were found to give lower estimates of fat. Generally, enzymatic treatment did not improve the precision of the Rose-Gottlieb analysis of preserved milk samples. When homogenized milk was preserved with formaldehyde, enzymatic treatment also failed to give reliable and reproducible estimates of fat by both the Gerber and Rose-Gottlieb methods. An additional step of proteolysis achieved by incubating formaldehyde-preserved milk with pronase (50 mg/100 ml) for 30 min at 37°C prior to fat estimation improved the ease and reliability of the Gerber but not the Rose-Gottlieb test.