Enterocin AS-48 is a cationic cyclic bacteriocin produced by Enterococcus faecalis with broad bactericidal activity. Currently we are assaying the efficacy of AS-48 as biopreservative in foods. In this work we have applied the spray drying process to different AS-48 liquid samples to obtain active dried preparations. We have also assayed different methods, heat, UV irradiation and filtration, to inactivate/remove the AS-48 producer cells from the samples. Best results were obtained for the sample from CM-25 cation exchange, for which it was also possible to completely eliminate/inactivate the producer cells by heat or UV irradiation without loss of activity. When added at 0.016% or 5% to Brain Heart Infusion broth or to skim milk, respectively, the AS-48 powder caused early and complete inactivation of Listeria monocytogenes. A partial inhibition of Staphylococcus aureus was achieved in broth and in skim milk supplemented with 2.5% and 10% AS-48 powder, respectively.