The experiments were performed according to the previously described protocol with minor modifications. In short, bacteriophages were diluted in the TM buffer solution to reach the initial titer of 10 5 PFU/mL (plague-forming units per milliliter). Then, 5 mg of selected food dye was added to 1 mL of phage suspension to reach a concentration of around 0.5% (w/v), and the mixtures were incubated at 4°C for 24 hours. After the incubation, the quantitative analysis of bacteriophage activity was performed using the droplet test on double-layer agar. The top-agar layer contained host cells of Escherichia coli BL21, E. coli C3000, or Salmonella enterica DSM 18522. A droplet test was performed by placing at least eight droplets (5 µL each) of each phage suspension on the top-agar layer. The remaining bulk of each sample was transferred to sterile glass Petri dishes (45 mm diameter). Irradiation was performed by placing glass Petri dishes inside a UV chamber (CL-1000 Ultraviolet Crosslinker, UVP; 5 × 8 W, 254 nm UV) for 1 minute, with plates positioned 15 cm from the radiation source. The second titration occurred after all the samples were exposed to UV-C radiation (λ = 254 nm) for 1 minute (corresponding to the energy of about 360 mJ/cm 2 ).