Proceedings Volume 2010 (format .pdf) - SimpBTH

keep the value of sensory and nutritional qualities of the product and themicrobiological control of food. PEF technology has no limitations related to thespread of lethal microorganisms in the treated product, for example, in heattreatment where this phenomenon can take place by conduction or convection. Theelectric field has a density, which enables a rapid and uniform inactivation of lethalmicroorganisms throughout the product volume.UV irradiation has been used for decades to disinfect water and is aneffective method for microbial decontamination of surfaces and food packaging.The Food and Drug Administration (2000) approved the UV irradiation asan independent method for preserving fruit juices, unless turbulences occur in theprocess. This condition is not required if the UV exposure is not the onlydecontamination factor.This paper gives the PEF and UV treatment, or a combination of PEF andUV inactivation of microbial liquid food.Experiments were performed using the micro-organisms: yeast, lactic acidbacteria and acetic bacteria in the systems: PEF alone, UV alone, UV + PEF andPEF + UV combined.2. Materials and methods2.1. Treated materialsExperiments were performed on suspensions of microorganisms in distilledwater sterilized by autoclaving for 30 min. at a pressure of 1 bar.Microorganisms for testing were taken from the collection ofmicroorganisms IC-DVV Calugareasca Valley, microorganisms present in wines:they used the yeast species Saccharomyces cerevisiae, strain PN III-11, the lacticbacteria Oenococcus oenos strain 149 and acetic bacteria Acetobacter aceti, strain11. After a program of successive replications, average liquid suspensions wereobtained, from which, after some dillutions, inoculation titers were made.Highlighting active microorganisms was performed using microbiologicalcontrol by membrane filter of 0.45 µ, followed by incubation environments specificto each type of microorganism:• for yeast, an agarose-based yeast extract, peptone and glucose to whichwas added chloramphenicol• for lactic bacteria, an agarose-based yeast extract, meat extract, peptone,sodium acetate, magnesium sulfate, glucose, to which was addedactidiona• for acetic bacteria, an agarose-based yeast extract, to which were addedactidiona and bromphenol blue.Experiments were conducted focused on the following aspects:307