This study evaluated the microbiological quality of fresh-cut bell pepper and ginger, as well as the inactivation effects of intense pulsed light (IPL) on E. coli ATCC 25922 inoculated in the fresh-cut samples by varying the treatment voltages (1,200-2,400 V) and time (1–7 min). The contamination levels of mesophilic bacteria, psychrophilic bacteria, yeast and mold for bell pepper and ginger were 6.64±0.81 and 6.35±1.96 log CFU/g, 6.75±1.13 and 5.63±1.89 log CFU/g, and 4.68±0.43 and 4.57±1.25 log CFU/g respectively. Through the IPL treatment at 2,400 V for 7 min, 2.04 and 2.11 log of E. coli ATCC 25922 inoculated in bell pepper and ginger were reduced, respectively, with a negligible temperature rise (< 2.2oC). Although the reduction rate varied, the bactericidal effect of E. coli ATCC 25922 showed an increase as treatment time and voltage increased. Under the same treatment conditions, temperature increased by 1.71oC and 2.13oC for bell pepper and ginger, respectively. These results demonstrate that IPL is a suitable device for inactivating E. coli ATCC 25922 on fresh-cut bell pepper and ginger.

Human mouth environment is known to include a variety bacteria, including Streptococcus spp., Staphylococcus spp., Actinomyces spp., Lactobacillus spp., Candida spp., Enterobacteriaceae, et al. Human oral microorganisms can cause dental caries, gingivitis, periodontitis, respiratory tract infection, and cardiovascular disease. Thus, right denture cleaning is essential to oral and general human health. The aim of this study was to evaluate the bactericidal effect of a sodium dichloroisocyanurate-based effervescent tablet (Aos Denti Germ, Aos Company, Chungbuk, Korea) against oral microorganisms. A total of 5 species Streptococcus spp. (Streptococcus anginosus, Streptococcus mitis, Streptococcus mutans, Streptococcus oralis, and Streptococcus sobrinus), Actinomyces oris, Candida albicans, and Escherichia coli were used in this study. All strains were exposed to the distilled water prepared with effervescent tablet. After the exposure, the mixture of strains and effervescent tablet was inoculated onto blood agar or MacConkey agar plate and cultured at 36℃. All strains were killed immediately on exposure to effervescent tablet. The results suggested that effervescent tablet could be used as an effective denture cleanser for dental hygiene.

The objective of this study was to characterize the bactericidal effect of 461nm visible-light LED on three common foodborne bacteria: Escherichia coli O157:H7, Staphylococcus aureus and Vibrio parahaemolyticus. Tests were conducted against pathogen strains that were treated with 461nm LED for 10 h at 15°C. The E. coli (ATCC 43894, ATCC 8739 and ATCC 35150) and the S. aureus (ATCC 27664, ATCC 19095 and ATCC 43300) had average reductions of 2.5, 6.6, 1.5, 2.5 and 2.0 log CFU/mL, respectively, after they were exposed for 10 h to 461nm LED light (p<0.05). In contrast, V. parahaemolyticus (ATCC 43969) had 6 log CFU/mL reductions after it was exposed for 4 h to 461nm LED light. The results showed that both the Gram-positive and Gram-negative bacteria were inactivated with 461nm LED light exposure. Also, the Gram-negative bacteria were more sensitive to the LED treatment than the Gram-positive bacteria. These results show the potential use of 461nm LED as a food preservation and application technology.