Samir Subedi, Lihui Du, Amritha Prasad, Barun Yadav, and M.S.Roopesh
Abstract
Several low water activity (aw) foods have been recently associated with Salmonella related outbreaks and recalls. The use of high intensity light pulses generated by light-emitting diodes (LEDs) is a novel approach to achieve microbial inactivation. This study compares the ability of light emitted by LEDs at wavelengths of 275, 365, 395, and 455 nm to inactivate microorganisms at different environmental relative humidity (RH) conditions. The exposure to LED radiant energy of 1199 J/cm2 at wavelengths of 365, 395, and 455 nm resulted in Salmonella reductions of 2.22, 2.48, and 1.61 logs CFU/g, respectively. Reductions in Salmonella cell counts of 1.07, 2.42, 3.67, and 2.64 CFU/g were observed in wheat flour after 60 min of 275, 365, 395, and 455 nm LED treatments, respectively, at 25 °C and an RH of 75%. Significant drying, oxidation of gluten proteins, and changes in the secondary structure of gluten were observed after LED treatments at all the light wavelengths tested. Significant color change of wheat flour was observed for all wavelengths LED except 275 nm. The results of this study will aid selection of LED wavelengths appropriate for inactivating microorganisms in low aw foods. This study presents the potential of LED treatment for simultaneous drying and microbial decontamination of foods.
