title: 405 ± 5 nm light emitting diode illumination causes photodynamic inactivation of Salmonella spp. on fresh-cut papaya without deterioration.
abstract: This study evaluated the antibacterial effect of 405 ± 5 nm light emitting diode (LED) illumination against four Salmonella serovars on fresh-cut papaya and on fruit quality at various storage temperatures. To determine the antibacterial mechanism of LED illumination at 0.9 kJ/cm2, oxidative damage to DNA and membrane lipids of Salmonella in phosphate-buffered saline solution was measured. The populations of Salmonella on cut fruits were significantly (P < 0.05) reduced by 0.3-1.3 log CFU/cm2at chilling temperatures following LED illumination for 36-48 h (1.3-1.7 kJ/cm2). However, at room temperature, bacterial populations increased rapidly to 6.3-7.0 log CFU/cm2following LED illumination for 24 h (0.9 kJ/cm2), which was approximately 1.0 log lower than the number of colonies on non-illuminated fruits. Levels of bacterial DNA oxidation significantly increased, whereas lipid peroxidation in bacterial membrane was not observed, suggesting that DNA oxidation contributes to photodynamic inactivation by LED illumination. LED illumination did not adversely affect the physicochemical and nutritional qualities of cut papaya, regardless of storage temperature. These results indicate that a food chiller equipped with 405 ± 5 nm LEDs can preserve fresh-cut papayas in retail stores without deterioration, minimizing the risk of salmonellosis.
authors.affiliation: Food Science and Technology Programme, Department of Chemistry, National University of Singapore, Science Drive 4, Singapore, 117543, Singapore.
authors.forename: Min-Jeong
authors.initials: MJ
authors.lastname: Kim
authors.affiliation: Department of Food and Nutrition, Yeungnam University, 214-1 Dae-dong, Gyeongsan-si, Gyeongsangbuk-do, 712-749, South Korea.
authors.forename: Woo Suk
authors.initials: WS
authors.lastname: Bang
authors.affiliation: Food Science and Technology Programme, Department of Chemistry, National University of Singapore, Science Drive 4, Singapore, 117543, Singapore; National University of Singapore (Suzhou) Research Institute, No. 377 Linquan Street, Suzhou Industrial Park, Suzhou, Jiangsu, 215123, China. Electronic address: chmyukhg@nus.edu.sg.
authors.forename: Hyun-Gyun
authors.initials: HG
authors.lastname: Yuk
mesh_terms: D029441:Carica / Q000382:microbiology* / Q000528:radiation effects; D015169:Colony Count, Microbial; D004269:DNA, Bacterial / Q000528:radiation effects; D004203:Disinfection / Q000295:instrumentation*; D005514:Food Irradiation; D005516:Food Microbiology; D063427:Food Quality; D008027:Light; D012034:Refrigeration; D012475:Salmonella / Q000528:radiation effects*; D012480:Salmonella Infections / Q000517:prevention & control
chemical_list: D004269:DNA, Bacterial
keywords: 405 nm-light emitting diode; Oxidative damage; Papaya; Photodynamic inactivation; Salmonella