## 2 Materials and Methods  
In our research, we investigated the coagulation process of raw milk samples using two different methods: enzyme-induced and acidic coagulation. During both types of coagulation, the dielectric behavior and the apparent viscosity of the milk samples were simultaneously monitored. The measurements were performed in three parallel replicates.  
The milk sample originated from a local cattle farming facility. Prior to the experiments, the samples were tested for somatic cell count (SCC), which was found to be around 110,000 cells/mL; therefore, the possibility of mastitis was ruled out. The initial pH of the sample was 6.50 \(\pm\) 0.05. For the enzyme-induced coagulation, 250 mL of milk sample was used, with the addition of MAXIREN 600 (DSM Food, Delft, The Netherlands, chymosin originated from _Kluyvermoyces lactis_, 600 IMCU/mL) enzyme in a concentration of 4.5 \(\upmu\)L/100 mL. The enzyme concentration was chosen in accordance with the manufacturer's standard recommendations. For the acid coagulation process, the same amount of milk was used, with an addition of industrial thermophilic yogurt culture (_Lactobacillus delbrueckii_ subsp. and _Streptococcus themophilus_). The dosing concentration of the freeze-dried culture in the inoculated milk volume was within the recommended dosing range of 0.03 g/100 mL for industrial technology applications.  
During the two coagulation processes, the inoculated milk samples were kept under a constant 40 \(\pm\) 1.5 \({}^{\circ}\)C temperature--this range falls within the optimal range for both the applied enzyme and the bacterial culture. To maintain the inoculation temperature, the sample containers were placed in a water bath (Medline BS-11).  
The investigation of the dielectric behavior covered the measurement of the dielectric constant (\(\epsilon^{\prime}\)) every 5 min in the first 30 min of the experiment and afterward every 10 min. These parameters were determined by using a DAK (dielectric assessment kit) type 3.5 (SPEAG GmBh, Bad Aibling, Germany) with an open-ended dielectric sensor connected to a vector network analyzer (VNA, type ZVL-3, Rhode & Schwarz GmBh, Munich, Germany) with a 50 Ohm coaxial power supply line at a frequency range of 200-2400 MHz. The values of the dielectric properties as a function of frequency were obtained from the average of 3-3 measurements at 10 different points, and the arithmetic mean of these measurements was used to determine the values of the investigated parameters associated with a given measurement point.  
The change in viscosity during milk coagulation was monitored using an SV-10 vibro viscometer (A & D Company, Tokyo, Japan). The principle of the measurement is that the two thin metal plates of the instrument are vibrated by electromagnetic forces, which, when immersed in the material to be measured, cause a change in vibration. In the case of milk and other colloidal systems, we can measure the apparent viscosity, which is always determined by the measurement circumstances. The determination of change in viscosity also took place every 5 min in the first phase (0-30 min) and 10 min afterward (30-60 min). The schematics of the experimental setup can be observed in Figure 1.  
Figure 1: Experimental arrangement (from left to right: dielectric assessment kit, VNA, dielectric sensor submerged in the milk sample, viscometer probe, viscometer unit).