Inactivation of vegetative cells, germinated spores, and dormant spores of Bacillus atrophaeus by pulsed electric field with fixed energy input

Abstract

Increasing the electric energy input during pulsed electric field (PEF) treatment is a straightforward technique to boost the efficiency of microbial inactivation. However, drawbacks such as electrode corrosion, arc formation, and high cost are also involved. This study aims to investigate the impact of medium conductivity (σ), electric field strength (E), and the number of pulses (N) on the inactivation of vegetative cells, germinated spores, and dormant spores of Bacillus atrophaeus with fixed energy input. Our results indicated that (1) vegetative cells were susceptible to PEF treatment, and the relative importance of E, N, and σ was E > N > σ; (2) germinated spores were more resistant to PEF treatment than vegetative cells, and the relative importance of E, N, and σ was N > E > σ; and (3) similar to the thermal resistance property, dormant spores were also highly resistant to PEF treatment and were not significantly inactivated in our experiment setting. It is concluded that the degree of PEF resistance of cell at different physiological states may be related to its structure and size. This study added to the body of knowledge on selecting PEF treatment settings and gave insight into the scaling up of PEF applications in the food processing industry.