Pulsed electric field (PEF) treatment can be used to facilitate microbial cell lysis. The aim of this paper is to investigate this effect of PEF treatment on microalgae. The PEF system used in this paper consists of a pulse generator and treatment cell with parallel-plane metallic electrodes. The PEF treatment of microalgae, Spirulina, was conducted using 33.3 and 66.7-kV/cm electric field impulses. The efficiency of the PEF treatment for inactivation of microalgae was assessed by comparison of the growth curves of PEF-treated and untreated samples. Results showed that growth of microalgae can be stopped by the application between 100 and 500 high-field impulses with field magnitude 33.3 kV/cm. When the field is increased to a magnitude of 66.7 kV/cm, the growth of microalgae can be stopped by application of 50 impulses. Overall, this paper confirms that PEF treatments can be used for the inactivation of algae and the energy consumption of the PEF process can be reduced using suspensions with lower electrical conductivity.

Pulsed electric field (PEF) treatment can be used for non-thermal inactivation of microorganisms. The aim of this paper is to investigate PEF treatment of yeast, Saccharomyces cerevisiae, using three different field waveforms: square; non-oscillating exponential and oscillating exponential. The PEF system used in this paper consists of a pulsed power supply and a parallel-plane metallic electrodes treatment cell located in an air-pressurised chamber. PEF treatment of the yeast was conducted using electric field impulses with magnitudes of 67 kV/cm and 80 kV/cm. The efficacy of the PEF treatment for inactivation of the yeast cells was assessed by comparison of the PEFtreated and untreated yeast populations. Results showed that ~3-log10 reduction in the yeast population can be achieved with 100 impulses using all tested waveforms. Amongst all three tested waveforms non-oscillating exponential impulses demonstrated improved PEF performance. The effect of duration of treatment and peak magnitude of the field on the PEF process is discussed.

Pulsed electric fields (PEFs) can cause irreversible damage to bio-membranes and may result in inactivation of microorganisms. The aim of this paper is to investigate the PEF treatment of the yeast Saccharomyces cerevisiae, using a novel treatment cell with parallel-plane electrodes coated with a 2-μm thin TiO ₂ film. Two different PEF waveforms, square and exponential, with magnitudes of 67 and 80 kV/cm were used in this study. The efficacy of the PEF treatment was assessed by a comparison of the surviving treated and untreated yeast populations, and it was shown that a treatment cell with TiO ₂ -coated electrodes can be successfully used for the PEF treatment of microorganisms: 3-log10 reduction in the yeast population was achieved with 100 impulses. The energy efficacy of the PEF process in the proposed treatment cell has been compared with the energy losses in the PEF treatment cell with uncoated, conductive electrodes. It is shown that the electrodes coated with TiO ₂ provide better performance compared with the traditional uncoated electrodes.

As a nonthermal microbial inactivation technology, pulsed electric field (PEF) treatment technology shows potentials in liquid food sterilization and other biological applications. The purpose of this study is to investigate the effect of PEF treatment on sterilization, the physical and the chemical properties of raw milk. Fresh raw milk samples were subject to PEF process with electric field strength ranged from 15 to 35 kV/cm for 1.25–5 ms in this study. The sterile rate and the shelf-life were evaluated and compared for PEF-treated, pasteurized, and untreated raw milk samples. It was demonstrated that similar inactivation effect was achieved as compared with pasteurization when raw milk was PEF-treated for 5 ms using 35-kV/cm field strength. The concentration of protein and free amino acids (FAA) was also measured and the results indicated that the PEF process promoted the protein-FAA transition as the concentration of FAA in the raw milk sample increased by as much as 14%. It is also shown that the input energy density of PEF treatment can be the deciding factor which affects both inactivation of microorganisms and the transformation of composition in the liquid food.

The effects of electrode topology on pulsed electric field (PEF) inactivation of microorganisms was investigated in the present study. Three PEF treatment chambers with different electrode topologies, which were parallel-plane, coaxial, and co-field respectively, were designed and built. PEF inactivation of yeast Saccharomyces cerevisiae suspension was conducted using these chambers with different electric field strength and a number of impulses. The performance of PEF inactivation was assessed by comparison of the population density of treated and untreated yeast samples. The results showed that the sterilization rate, as a function of the specific energy density, followed the same tendency regardless of the electrode topology, electric field strength, or the number of impulses. This strong correlation suggested that the specific energy density (energy per unit mass) could play a dominant role in the PEF inactivation of microorganisms once the threshold field strength was reached.

Growing attention has been paid to nonthermal plasma treatment technology and its effects on the degradation of organic matter, especially for antibiotics. However, the majority of the conducted research has focused on the experimental results. Rare attempts were made to analyze the reaction mechanism at the microscopic level. In this paper, molecular dynamics simulation and reactive forcefields were used to investigate the reaction mechanism of different plasma particle interactions with azithromycin molecules. The simulation results indicated that the degradation of azithromycin was caused by the destruction of C-H and C-C bonds, followed by the formation of C=C and C=O bonds when reacted with the active particles. It was also found that the ability of degrading azithromycin varied among the different types of active particles. The oxygen atoms had the strongest ability to decompose the azithromycin molecule, with 38.61% of the C-H bonds broken as compared with other oxygenated species. The findings from this computational simulation could provide theoretical support and guidance for subsequent practical experiments.