Synergistic Effects of Mild Heating and Dielectric Barrier Discharge Plasma on Reduction of <em>Bacillus cereus</em> in Red Pepper Powder

Abstract

The synergistic efficacy of combined treatment mild heat (MH) and dielectric barrier discharge (DBD) plasma in Bacillus cereus-contaminated red pepper powder was tested. A cocktail of three strains of B. cereus (NCCP 10623, NCCP 14579, ATCC 11778) was inoculated onto red pepper powder and then treated with MH (60 ℃ for 5-20 min) and DBD plasma (5-20 min). Treatment with MH and DBD plasma alone for 5~20 min resulted in reductions of 0.23~1.43 and 0.12~0.96 log CFU/g, respectively. Combined treatment with MH and DBD plasma was the most effective at reducing B. cereus counts on red pepper powder and resulted in log-reductions of &amp;ge; 6.0 log CFU/g. The largest synergistic values (4.24-4.42 log) against B. cereus in red pepper powder were obtained by the combination of 20 min MH and 5~15 min DBD plasma. Hunter color &amp;lsquo;&amp;lsquo;L&amp;rsquo;&amp;rsquo;, &amp;lsquo;&amp;lsquo;a&amp;rsquo;&amp;rsquo;, and &amp;lsquo;&amp;lsquo;b&amp;rsquo;&amp;rsquo; values of the combination-treated samples were not significantly different from those of non-treated samples. Also, no significant (p &amp;gt; 0.05) differences in pH values between samples were observed. Therefore, these results suggest that the combination of MH treatment and DBD plasma can be potentially utilized in the food industry to effectively inactivate B. cereus without incurring quality deterioration of red pepper powder.