Background. The aim of the study was to determine the effect of the pressure of 200 ÷500 MPa/20 oC/15 min. on the selected characteristics of goat’s milk. The total bacterial count (OLD), psychrotrophic bacterial count, acidity, protein, casein and free fatty acid (FFA) content were determined and microscopic images of the milk were analyzed. The analyses were performed immediately after pressure application and during 14 days of storage at 4 ^oC.
Results and conclusions. The application of the pressure of 200 ÷ 400 MPa resulted in a significant (p ≤ 0.05) pressure-dependent reduction in OLD. Applying the pressure of 500 MPa resulted in a complete reduction of OLD. Psychrotrophic bacteria were not found immediately after the application of the pressure of 300 ÷ 500 MPa; however, an increase of these bacteria was observed during storage. The application of the pressure of 200 ÷ 500 MPa had no effect on acidity immediately after pressurization and significantly (p ≤ 0.05) reduced the increase in milk acidity during storage. Pressurization resulted in an increase of casein content, while no significant change of protein content was found (p > 0.05), which may be due to the interaction of casein with whey proteins. The effect of the pressure of 200 ÷ 500 MPa resulted in an increase in FFA content. During storage, the FFA content was lower in the pressurized milk compared to the control milk. Differences were found in the microscopic images of control and pressure-treated milk immediately after pressurization and after storage. These changes were due to the aggregation of fat globules immediately after pressurization and the formation of clusters of fat globules and coagulated protein during storage.