Freezing point of raw and heat-treated goat milk

Abstract

The freezing point (FP) was established in 48 bulk tank samples of raw and 48 samples of pasteurized goat milk that were collected in the course of lactation. Alongside, non-fat solids (NFS) content was monitored. Milk freezing point measurements were carried out using the thermistor cryoscope method in compliance with the standard CTS 570538 (1998). The mean freezing point of raw milk was found to be in an interval of -0.5513 ± 0.0046°C, variation ranged from -0.5466°C to -0.5567°C, with higher values in the spring months and a drop at the end of lactation. FP corresponded to the NFS content. The average freezing point of goat milk heat-treated on the farm to the temperature of 72°C over a period of 20 s was -0.5488 ± 0.0046°C, pasteurisation brought an average increase in FP by 0.0025°C.

Keywords

• cryoscopy
• milk
• goats
• pasteurization
• freezing point