Microbial decontamination of red pepper powder by cold plasma

Abstract

Effects of the microwave-powered cold plasma treatments (CPTs) on the inhibition of microorganisms in red pepper powder, including Aspergillus flavus and Bacillus cereus spores, were investigated. Combinations of heat treatment with CPT were investigated for the inhibition of B. cereus spores on the powder. The number of A. flavus was reduced by 2.5 ± 0.3 log spores/g by the CPT with nitrogen at 900 W and 667 Pa for 20 min. CPT at 900 W and 667 Pa for 20 min inhibited naturally occurring total aerobic bacteria in the red pepper powder by approximately 1 log CFU/g. B. cereus spores were inhibited (3.4 ± 0.7 log spores/g reduction) only when heat treatment at 90 °C for 30 min was integrated with the CPT using a helium-oxygen gas mixture at 900 W. Fermi's model and Weibull model adequately described the inhibition of A. flavus on the red pepper powder by the CPT. The changes in treatment temperature and water activity were less than 5.0 °C (initial temperature: 23.8 °C) and 0.22, respectively, and were affected by both treatment power and time (P < 0.05). The CPTs have demonstrated the potential to reduce the microbial counts of red pepper powder and other powder products.

Keywords: Bacillus cereus; Cold plasma; Fermi's model; Nonthermal process; Red pepper; Weibull model.