The first set of experiments was carried out on three different microbial strains grown to the stationary phase in an aerated incubator (Haeraeus Instruments): bakery Saccharomyces cerevisiae (ATCC 16664), E. coli O157:H7 (ATCC 26), Lactobacillus delbrueckii sp. lactis (ATCC 4797). S. cerevisiae yeasts were grown in MRS broth (OXOID) at 32 C for 40 h, E. coli in LB (Luria Broth) nutrient broth at 37 C for 24 h, L. delbrueckii in MRS (de Man–Rogosa–Sharpe) nutrient broth at 32 C for 48 h. The cultures were centrifuged at 5000 rpm for 5 min at 20 C and the pellets were suspended to a desired concentration in the processing medium (sterile water, orange, red-orange, pineapple juice). Table 1 reports the properties of the commercial juices used for the experiments and evaluated at 25 C.