The Variability of the Freezing Point of Fresh Raw Milk

Abstract

The freezing point value is generally recognized as the least variable property of milk and the best single index of "added water." The lactose and chloride concentration of milk account for about 75% of the freezing point depression, and one tends to compensate for the changes in concentration of the other. Most of the variability in the freezing point value has been attributed to changes in the concentration of the non-chloride ash fraction of milk. The official upper limit in the United States is —0.530°C. Evidence exists that the freezing point value of milk varies with season, feed, ambient temperature, grazing, carbohydrate content of the ration, breed, time of milking, access to water, weather, morning or evening milking, and the time interval between feeding and milking. Many of these factors are interrelated. Until recently all published values for United States herd milk samples ranged from —0.510 to —0.585°C, and for individual cows from —0.513 to —0.583°C. The greatest difference reported in the United States between morning and evening milk samples is —0.013°C. The reported range for United States authentic samples is -0.532 to -0.578°C.