Milk freezing point testerThe principle of
The principle of a freezing point meter is that the flow of coolant causes the temperature of the measured liquid to decrease, while stirring the measured liquid to dissipate heat from its surface, resulting in the cooling of the measured liquid. The temperature of the measured liquid decreases. When the temperature of the measured liquid approaches the temperature at which the density of the measured liquid is high, the specific gravity of the surface measured liquid is relatively high, and the specific gravity of the inner measured liquid decreases relatively. At this time, convective mixing occurs between the surface and inner measured liquids. The cooling process brings the surface cooling of the measured liquid to the inner layer, and also carries the crystallization heat released when the inner layer forms ice crystals to the surface. The measured liquid is cooled again until the density of the entire measured liquid is uniform and stable before stopping. When the temperature of the measured liquid drops to freezing point and continues to dissipate heat, the measured liquid begins to freeze.
The probe measures the freezing point temperature of the mixed sample and uses the internal calculation formula of the instrument to obtain the percentage of water added to the milk sample. The freezing point meter is used to accurately detect the addition of water to milk. Due to the dissolution of various components such as fat and protein in milk, the freezing point is lower than that of water. The average freezing point of normal milk is -0.530 degrees Celsius, while the freezing point of water is 0 degrees Celsius. If water is added to milk, the freezing point of the entire sample will rise. Under normal circumstances, when 1% water is added, the freezing point of the mixed sample will increase by about 0.0053 degrees Celsius. When 100% water is added, the temperature will increase by 0.530 degrees Celsius. At this time, the instrument displays a freezing point temperature of 0 degrees Celsius, while the water added is 100%.