Effect of radio frequency energy on biological membranes and microorganisms

Abstract

In order to study the use of radio frequency (RF) heating to inactivate microorganisms at milder temperatures, its effect on model systems (liposomes) and whole cells was evaluated. The effect of RF energy on leakage of 6-carboxyfluorescein from liposome vesicles was studied. Both influences of the applied frequency and of membrane composition were demonstrated. Radio frequency fields appeared to result in membrane damage which could not be attributed to thermal effects. Exposure of liposomes to RF fields with frequencies of 27 and 100 MHz resulted in lysis of the vesicles. In addition, growth of Saccharomyces cerevisiae appeared to decrease in the presence of RF fields of 27 and 100 MHz. Effects of RF fields on Erwinia carotovora cells at sublethal temperatures could not be demonstrated. Moreover, when RF energy was applied as a heat treatment, no additional effects were detectable. Advantages of RF heating are probably not to be found in inactivation treatments at milder temperatures. It is concluded that RF energy can serve as an alternative heating mode in terms of quick and efficient reduction of microbial load, in specific cases. © 1996 Academic Press Limited.