Inibição da contagem de Salmonella Typhimurium em água pela aplicação de ultrassom e agentes químicos

Abstract

Salmonella sp. is considered one of the pathogens more important of higher virulence and prevalence in the cases of infections of food origin worldwide. Therefore, the food industry applies heat treatments for inactivation. However, in view of the inviability of the high temperature application in many processes, the present study was developed. The objective was to evaluate the ultrasound (US) in the Salmonella Typhimurium inactivation in water, using distilled water as the model system, free of interference and absence of suspended materials (protein, lipids, blood and other) or US combined with chemical agents to verify potentiality of Salmonella Typhimurium inactivation, in poultry slaughterhouse chiller water. The method evaluated in the inhibition was non-destructive and the chemical agents evaluated were hydrogen peroxide (H2O2) and chlorine dioxide (ClO2). Three full factorial designs (PFC) were realized: 1) PFC 22 in which the independent variables were sonication amplitude of 40% (-1) to 100% (+1) and time, 5 min (-1) to 15 min (+1); 2) PFC 2³, with independent variables sonication amplitude of 40% (-1) to 100% (+1), time, 5 min (-1) to 30 min (+1) and H2O2 concentration from 1% (-1) to 9% (+1) and, 3) PFC 2³ in which only the H2O2 concentration was replaced by the ClO2 concentration of 1 ppm (-1) to 150 ppm (+1) in relation to the PFC realized previously. The response studied was the count of Salmonella Typhimurium (UFC mL-1). Ultrasound isolated, studied in PFC 2², was not enough to demonstrate effects on the response studied (p > 0.05). In PFC 2³ combining US with H2O2, the variables sonication amplitude and H2O2 concentration had significant negative effects in Salmonella Typhimurium reduction (p < 0.05). When the PFC 2³ was performed combining US with the ClO2, it was observed that the response was negatively affected by the effect of ClO2 concentration (p < 0.05). The possibility of applying the ultrasound bath industrially in chillers waters, to chillers, on the conditions studied at 37 kHz and the levels of sonication amplitude and time variations were not efficient in inhibiting the pathogen. In contrast, it was concluded that addition of 74.5 (0, center point) and 150 ppm (+1) of ClO2 were completely efficient in Salmonella Typhimurium (9.73 log CFU mL-1) elimination.