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.

This study was conducted to evaluate the effect of light spectrum using red (660 nm), blue (460 nm), red and blue mixed (Red : Blue = 6 : 4) LED (light-emitting diode), and fluorescent lamp on antioxidant activities and functional components of dandelion (Taraxacum officinale). Total polyphenol contents in dandelion irradiated with the red and blue mixed or the red LED were 121.77 mg/100 g or 115.36 mg/100 g, respectively, which were greater than those in dandelion treated with blue LED and fluorescent lamp. Asparagine showed the highest content among amino acids in leaves and roots regardless of treatments. Total amino acid was the highest when illuminated with the red LED. DPPH (1,1-diphenyl-2-picrylhydrazyl) radical-scavenging activity and SOD (super oxide dismutase) activity of ethanol extracts were increased under all of the LED treatments compared with fluorescent lamp, and the antioxidant activities were increased by the red and the mixed LED illumination. The results indicate that application of the red and the mixed LED illumination promote antioxidant activity and increase functional components during cultivation of dandelion.

Investigation on oriental melon was carried out for 30 minutes starting at 7 PM every day from March 21 to May 24 to find out the effect of light emitting diode on seedling quality, grafting, growth and flowering of oriental melon. According to the result of the investigation, plant height was longer in Blue, Infrared, Red+Blue and Red treatment and leaf number was higher in Blue, Red+Blue and Infrared treatment than those of control. No big difference was identified between control and Yellow, Green, Ultraviolet treatments. Grafting rate was high in Green, Red+Blue and Green treatment. The number of flower evef}' week in control was nine, the number was almost 1 higher in White and Ultraviolet A treatments, but it was 1 to 4 lower in the rest of treatments. The number of female flowers of control was 10, however, it was 21 in Infrared treatment, 17 in White, 15 in Ultraviolet, 13 in Red+lnfrared, 12 in Blue and Red+Blue, 11 in Yellow and 8 in Green.