Inactivation of Salmonella on tainted foods: using blue light to disinfect cucumbers and processed meat products

Abstract

Foodborne illness resulting from infectious organisms occurring in vegetables and processed meat is a serious health concern in the United States. Improved and cost‐effective techniques for disinfection are needed. Visible light in the blue range (405 nm) was administered to processed meat that had been inoculated with Escherichia coli. One application of light energy at doses of 10, 30, 60, and 100 J/cm2 was applied, in vitro. In the case of vegetables contaminated with Salmonella (cucumbers), 464 nm light was used at 6, 12, and 18 J/cm2. In both cases, after 20 hours of incubation, colony‐forming units were counted and compared to controls to determine whether the light energy inhibited growth of E. coli or Salmonella. E. coli – 405 nm light at doses of 30, 60, and 100 J/cm2 were all effective inhibitors of the organism. Kill rates of 75.61 – 96.34% were achieved. Salmonella – 464 nm light at doses of 6, 12, and 18 J/cm2 produced significant inactivation of the organism. Kill rates of 80.23–100% were obtained. Blue light, delivered in the wavelength/dose combinations used in this study is an effective inhibitor of both E. coli and Salmonella on actual foodstuffs. Blue light should be considered as a potentially effective tool in the effort to protect humans from foodborne illnesses.

Antimicrobial blue light inactivation of pathogenic microbes: State of the art

“…In a study carried out by Guffey et al (Guffey et al, 2016), Salmonella and E. coli on actual food stuffs were significantly inactivated when exposed to 464 nm aBL at 18 J/cm 2 (inactivation rates 80.2–100%) and 405 nm aBL at 60 J/cm 2 (inactivation rates 75.6–96.3%), respectively.…”

Perspectives and Trends in the Application of Photodynamic Inactivation for Microbiological Food Safety

“…The inactivation of S . Typhimurium has also been attempted on cucumber surface without any exogenous PS (Guffey et al., ). From 464 nm LEDs of intensity 16.6 mW/cm 2 , light was made incident on pieces of cucumber from both sides.…”

“…A dose of 18 J/cm 2 was seen to eliminate all the bacteria on the cucumber surface. Though the recovery method used in this study was less than ideal (pressing the contaminated surface on agar), the presence of a significant antibacterial effect cannot be denied (Guffey et al., ). The levels of E. coli O157:H7 were also decreased on cucumbers by Glueck et al.…”

“…Guffey et al. () reported complete inactivation of E. coli O157:H7 on hot dogs subsequent to illumination with 405 nm LEDs at an irradiance of 83.3 mW/cm 2 . Though the dose (120 J/cm 2 ) eliminated the contamination completely, caution should be exercised while estimating the implications of the results, as the initial inoculum (75 CFUs) was very low and the recovery method (pressing the meat samples into the agar) was suboptimal.…”

Can light‐based approaches overcome antimicrobial resistance?

“…The aBL has been studied for killing E. coli in milk and Salmonella in orange juice (Ghate, Kumar, Zhou, & Yuk, ). There have also been studies of aBL for bacterial contamination on the surfaces of foodstuffs, such as fresh‐cut papaya (Kim, Bang, & Yuk, ), fresh‐cut mango (Kim, Tang, Bang, & Yuk, ), and processed meat (hot dogs; Guffey et al, ). Another possible application has been to extend the life‐time of fruits and vegetables postharvest, which is usually restricted by the growth of molds or the development of rot (Liao, Alferez, & Burns, ).…”