COMPARISON OF SKIMMILK FAT TESTS AND NEW VERMONT METHOD1,2

Abstract

A comparative study of skimmilk fat tests indicated the need for a more accurate method. Such a method was developed at the Vermont Agricultural Experiment Station. Called the Vermont method, this uses Patton's aqueous reagent of n-butylamine and n-butanol, Babcock equipment and glassware, and the TeSa water bath. This Vermont method is simple, inexpensive, and no more time cousuming than the Babcock procedure. Twenty-two trials were performed whereby skimmilk samples were collected weekly from 6 milk dealers and tested by 5 or 6 methods. Several milk dealers sold skimmilk that consistently tested higher than 0.50% fat as determined by the Mojonnier procedure. It was apparent that results obtained with the Babcock, Wildasin Babcock (use of a quaternary ammonium compound), and American Association (modified Babcock using n-butanol) methods showed poor fat percentage agreement over the legal fat range, compared with the Mojonnier procedure. Data from the Gerber and Vermont methods showed very close agreement with that of the Mojonnier procedure. Statistical analysis indicated a significant difference (P < 0.01) between fat percentages obtained using the Babcock, Wildasin Babcock, and American Association methods when compared with the Mojonnier technique. Results from the Gerber and Vermont methods were not significantly different from those obtained with the Mojonnier procedure. Precision for the Vermont method was determined by testing 10 replicate samples of 2. different skimmilks. The means and standard deviations for the samples are as follows: 0.12.% ± 0.005, and 0.44% ± 0.007. Use of the Vermont method must await results of studies from other laboratories.