Evaluation of cold plasma treatments for improved microbial and physicochemical qualities of brown rice

Abstract

This study evaluated the microbial and physicochemical characteristics of brown rice (BR) treated with cold plasma. Cold plasma was generated in a plastic container (250 W, 15 kHz, ambient air) and the cold plasma was applied to BR samples for periods of 5, 10 and 20 min. When BR samples were inoculated with Bacillus cereus, Bacillus subtilis, and Escherichia coli O157:H7, a 20 min plasma treatment resulted in a reduction in bacterial counts by approximately 230 log CFU/g. The pH of the BR decreased slightly after the 5 min plasma treatment. BR with hunter color L* showed an increase in pH, and the a* and b* values decreased as a result of the plasma treatment. The alpha-amylase activity and water uptake rate increased significantly (p < 0.05), while hardness decreased significantly (p < 0.05). The results of this study indicate that cold plasma treatments can improve the microbial quality of BR and produce slight changes to the physicochemical quality of BR. (C) 2016 Published by Elsevier Ltd.