| Summary: | Vegetative cells of <i>Listeria monocytogenes</i> and <i>Escherichia coli</i> and spores of <i>Bacillus subtilis</i> and <i>Aspergillus niger</i> were inoculated in soy milk at an initial concentration of ≈5 log CFU/mL. Inoculated and control (non-inoculated) soy milk samples were submitted to three types of treatments using a tubular annular thin film short-wave ultraviolet (UV-C) reactor with 1 mm of layer thickness. Treatments applied depended on the flow rate and the number of entries to the reactor, with UV-C doses ranging from 20 to 160 J/mL. The number of entries into the reactor tube (NET) was established as the most determining parameter for the efficiency of the UV-C treatments. Conidiospores of <i>A. niger</i> were reported as the most resistant, followed by <i>B. subtilis</i> spores, while vegetative cells were the most sensible to UV-C, with <i>Listeria monocytogenes</i> being more sensible than <i>Escherichia coli.</i> Treatments of just 80 J/mL were needed to achieve a 5 log CFU/mL reduction of <i>L. monocytogenes</i> while 160 J/mL was necessary to achieve a similar reduction for <i>A. niger</i> spores.
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