Base Freezing Point Values of Untainted Goat, Sheep, and Water Buffalo Milk
By J. Rosenman, E. Garry, Advanced Instruments, Inc., Norwood, Mass.
In the dairy industry, control systems are in place to ensure milk quality. A thermistor cryoscope is used to accurately determine the freezing point of milk. The average freezing point of pure cow milk is -0.543°H. Milk adulterated with extraneous water, whether accidentally or intentionally, will have an elevated freezing point. The objective of this study was to determine base freezing point values for untainted goat, sheep, and water buffalo milk.
Unadulterated bulk tank goat, sheep, and water buffalo raw milk samples were subjected to heat treatment at 63° ± 1C for 30 minutes prior to freezing point analysis. Freezing points of 378 goat, 46 sheep, and 87 water buffalo samples were tested on the Advanced® Cryomatic Milk Cryoscope, Model 4C2 according to the manufacturer’s instructions. The mean freezing point of 378 bulk tank goat milk samples was -0.561 ± 0.009°H. The mean freezing point of 46 bulk tank sheep milk samples was -0.575 ± 0.010°H. The mean freezing point of 87 bulk tank buffalo milk samples was -0.521 ± 0.027°H.
Base freezing point values were used to generate tables for estimating extraneous water in goat, sheep, and water buffalo milk. It is recommended, however, that laboratories establish their own base freezing point values for goat, sheep, and water buffalo milk in order to accurately quantify extraneous water.
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