A multi-vessel Resato unit (FPU-100-50, serial no. 14685/42798, Roden, Netherlands) was used for the application of the HPT processing; per vessel, one bag was processed at the time. Before the application of the treatments, the bags were inserted 1 min to equilibrate the sample temperature to the initial working temperature. Vessel volume was approximately 50 cm3 (dimensions were approximately 3 cm of diameter and 8 cm of height). The machine uses ethylene glycol as pressure-transmitting medium, and was equipped with thermostatic jacket for temperature control. Initial temperature of glycol was 50, 65 and 80 °C and the pressures applied were 300, 600, 900 MPa for 1 min. This holding time was chosen because it was short enough to maintain a quasi-constant temperature of processing. This short holding time avoided the loss of heat during processing. Pressure build-up rate was 10 MPa s− 1. Temperature of milk during HPT treatment could not be measured during processing. We have measured the temperature changes of the pressurization medium (the thermocouple was in the middle of the cylinder vessel), so temperature of milk bags should be lower. However due to the low amount of milk in each bag, differences of temperature between the milk and the pressurization medium should not be very different.