Intense light pulses in combination with lemongrass essential oil in vapor phase to inactivate Salmonella Typhimurium on sunflower and quinoa seeds

Abstract

The response of Salmonella Typhimurium to combined treatment involving intense light pulses (ILP) and exposure to different concentrations of lemongrass (Cymbopogon citratus) essential oil (LEO) in vapor phase was assessed on sunflower and quinoa seeds. Microbiological analyses were performed by inoculating sunflower and quinoa seeds with S. Typhimurium (10⁶ CFU/g) and counting microbial populations pre- and post-processing. Moisture content, peroxide value, color, and sensory evaluation were performed for the best ILP + LEO treatments in terms of log reductions of inoculated Salmonella. For ILP treatments, S. Typhimurium was significantly (p < 0.05) reduced on both inoculated seeds since 3.0 and 2.3 log-cycle reductions were achieved with 12 s treatment (16.20 J/cm²) on sunflower and quinoa, respectively. Subsequently, seeds with the surviving populations of S. Typhimurium were exposed to LEO vapor phase. They were inactivated by ∼3 log with a 360 μl LEO/L_air. The Weibull model accurately described data from S. Typhimurium inactivation during ILP treatments (R² > 0.96, RSME <0.28). Seeds treated with 16.2 J/cm² ILP had similar physicochemical and sensory properties to untreated ones; however, ILP + LEO impacted the seeds’ odor. Combining ILP treatment and LEO in the vapor phase resulted in an innovative alternative to increase microbial inactivation in seeds.