Impact of factors affecting the efficacy of intense pulsed light for reducing Bacillus subtilis spores

Abstract

This study investigated how the following four intense pulsed light (IPL) treatment factors affect the inactivation of Bacillus subtilis (KCCM 11,315) spores: distance between the sample and IPL lamp (8, 13, and 18 cm), pulse width (0.5, 1.3, and 2.1 ms), charging voltage (1000, 1200, and 1400 V), and processing time (10, 20, and 30 s). The results showed that all four factors considerably influenced the spore inactivation rate in different ways. Excluding processing time, which does not affect the pulse itself, the effect was largest for pulse width, followed by distance, and charging voltage. The optimal treatment condition that maximized the inactivation rate was a distance of 8 cm, a pulse width of 2.1 ms, a charging voltage of 1000 V, and a processing time of 30 s, which together produced a 6 log reduction. It revealed that individual factors need to be investigated together for achieving the optimal condition of IPL.

Model prediction of inactivation of Aeromonas salmonicida grown on poultry in situ by intense pulsed light

“…This is mainly due to the fact that the sterilization effect is influenced by the pulsed voltage, and when the voltage increases, its energy passage is also increasing, which will lead to an increase in the inactivation effect as well [32]. Hwang et al [33] found that when microorganisms are exposed to IPL, they first have some resistance until the IPL exceeds a specific intensity threshold, showing a rapid decline. This is more similar to the phenomenon of showing a rapid decrease after 5 s mentioned in the results, so it is reasonable to speculate that 5 s is their specific intensity threshold in this paper.…”

Physical Treatments to Control Clostridium botulinum Hazards in Food

“…This high-intensity light includes a wide wavelength ranging from 200 to 1100 nm, including UV (200–400 nm), visible (400–700 nm), and near-infrared region (700–1100 nm) radiation waves [ 133 ]. As the penetration of light through opaque objects is limited, this technology is currently applicable for treating surfaces and transparent fluids [ 141 , 142 ].…”

“…They observed that the ILP treatment reduced the bacterial load on blueberries, tomatoes, and lettuce shreds by 4.5, 4.4, and 2 logs, respectively, on the spot-inoculated fresh produce, whereas only about 2 logs were reduced for all the dip-inoculated samples. Hwang et al [ 142 ] used ILP treatment conditions of a lamp DC voltage of 1.8–4.2 kV, a pulse width of 0.5–1.0 ms, a frequency of 2 Hz, and a treatment time of 1–5 min for four powder foods. Under a total energy fluence of 12.31 J/cm 2 , the total mesophilic aerobic bacteria reductions of 0.45, 0.66, 0.88, and 3 logs CFU/mL were recorded for ground black pepper, red pepper, embryo buds of rice, and sesame seeds, respectively.…”