Anais do Simpósio Latino Americano de Ciências de Alimentos
Anais do 14 SLACA - Simpósio Latino Americano de Ciência de Alimentos

Salmonella typhimurium is a pathogen that causes foodborne illnesses, but it is quickly inactivated by thermal treatments. Salmonella population can be reduced by high-energy pulsed light (PL), a non-thermal and innovative disinfection technology with minor changes in the product quality. However, the interactions of bacteria with substrates may change their efficiency. This study evaluated the inactivation of Salmonella typhimurium inoculated in chicken breasts (CB) by PL. The influence of the inoculum concentration (103-106 CFU/cm2 of the CB), fluence levels of 1.91 and 5.63 J/cm2, contact time between Salmonella and CB before the PL (1, 5, 15, and 60 min), the inoculum volume spread (5 and 50 µL) on the samples, and the thickness of water layer on the CB before inoculation were studied. Salmonella inactivation was 1.08±0.12 and 1.45±0.02 UFC/cm2 for 1.91 and 5.63 J/cm2 of fluence level, respectively, independent of the initial concentration. The increase from 5 to 15 min of contact with the CB before PL treatment caused a decrease of Salmonella inactivation from 3.22±0.53 to 1.41±0.18 UFC/cm2. It is reasonable to infer that Salmonella in contact with CB migrated quickly to regions where PL does not reach. The inoculum volume spread on CB also impacted the Salmonella inactivation for a contact time of 1 min; for 5 µL, the count plate was <10 UFC/cm2, while for 50 µL, a reduction of 2.62±0.42 UFC/cm2 was observed, the same behavior was also found for longer times, in high volumes the bacteria probably overlap, reducing the inactivation. The thickness of the water layer on CB surface plays a vital role in the Salmonella inactivation by PL. Salmonella is motile, and the water layer facilitates their migration, which had a protective effect. These results showed that a successful PL application needs to evaluate the interaction of microorganisms, substrate, and PL parameters.