Inactivation of foodborne pathogens in powdered red pepper (Capsicum annuum L.) using combined UV-C irradiation and mild heat treatment

Abstract

This study was performed to investigate the effectiveness of combined ultraviolet (UV-C) irradiation and mild heating as an alternative to conventional inactivation of foodborne pathogens, including Escherichia coli O157:H7 and Salmonella Typhimurium on powdered red pepper. A cocktail of three strains of E. coli 0157:H7 ATCC 35150, ATCC 43889, ATCC 43890) and S. Typhimurium (ATCC 19585, ATCC 43971, DT 104) was inoculated onto powdered red pepper and then treated with UV-C irradiation and mild heat. A constant UV intensity (3.40 mW/cm(2)) of the emitting lamps was applied to samples for 5, and 10 min at 25, 35, 45, 55, and 65 degrees C, respectively. Also, quality change of powdered red pepper was measured in order to identify the efficiency of combined treatment. The reduction levels of E. coli O157:H7 and S. Typhimurium on powdered red pepper when treated with UV-C irradiation alone at 20.4 ki/m(2) for 10 min was 0.22 and 0.29 log CFU/g, respectively. While, combined treatment with mild heating at 65 C reduced the surviving numbers of each pathogens by 2.88 and 3.06 log CFU/g, respectively. Although the inactivation efficiency was influenced less by the UV-C radiation dose, the synergistic effect was observed with increasing temperature and UV-C radiation dose. CIE color value and extractable color value were not significantly (P > 0.05) different between non-treated and combination treated samples. The moisture and capsaicinoids contents showed significant (P < 0.05) differences when treated at 65 C because of sample drying during heat treatment. Therefore, these results suggest that UV-C irradiation combined with mild heating can be utilized by the food industry in order to effectively inactivate E. coli O157:H7 and S. Typhimurium without incurring quality deterioration of powdered red pepper. (C) 2014 Elsevier Ltd. All rights reserved.