Purpose: The purpose of this study was to evaluate the enhanced thermal inactivation of Cronobacter sakazakii by the inclusion of parabens and to ultimately develop mathematical models that describe the relationship between heating temperature, parabens identity, and parabens concentration.
Methods: C. sakazakii607 (heat-resistant) was subjected to five parabens (methyl, ethyl, propyl, butyl, heptyl) in various concentrations under three temperatures (52°C, 55°C, 58°C). Thermal inactivation was conducted in a submerged coil apparatus using Brain Heart Infusion as the heating menstruum. Cells were surface plated on tryptic soy agar (TSA) and MacConkey agar (MA). After enumeration, survivor curves were plotted and compared using ANOVA. Primary and secondary models were developed using OriginPro etc.
Results: Parabens produced a significant enhancement of thermal inactivation that was concentration dependent and increased with increasing alkyl chain length. For example, at 58°C butyl-paraben, at concentration of 0 ppm, 31.25 ppm, 62.5 ppm, 125 ppm, resulted in log reductions of 2.5, 4.0, 5.5, >7.0, respectively, within 900 seconds. At a concentration of 125 ppm in conjunction with heating at 58°C, methyl, ethyl, propyl, butyl, and heptyl parabens produced log reductions of 3.0, 3.5, 5.5, 7.0, and >7.0, respectively. The comparison of TSA vs. MA counts indicated 0.5-2.0 log of injury. The three parameters (concentration, alky side chain length, and heating temperature) acted synergistically on thermal inactivation of C. sakazakii607, even at temperatures that little impact was observed with the 0 ppm controls.
Significance: These data suggest that pasteurization can be enhanced through synergistic action of mild heat treatments and inclusion of parabens. These data can be used to develop mathematical models that effectively describe how these three process parameters can be applied in the industry.