Anti-Salmonella Monoclonal antibody, Clone 202/460

A novel impedance biosensor was developed based on the interdigitated microelectrodes using H2O2 to reduce SiO2@MnO2 nanocomposites into Mn2+, resulting in significant impedance changes in the rapid and ultrasensitive detection of Salmonella typhimurium (S. typhimurium). The captured S. typhimurium monoclonal antibodies (MAb1) were assembled on the outer layer of the magnetic beads (MBs) for specific enrichment and isolation of S. typhimurium cells in complex samples. The recognized S. typhimurium monoclonal antibodies (MAb(2)) were immobilized on the surface of the SiO2@MnO2 nanocomposites, which could react with the MBs- S. typhimurium conjugates to form the MBs- S. typhimurium -SiO2@MnO2 sandwich complexes. The MnO2 on the surface of the sandwich complexes was reduced into Mn2+ by using H2O2 achieving obvious impedance change that could be detected by the interdigitated microelectrodes. The recoveries for S. typhimurium cells at the concentrations between 2.0 x 10(1) and 2.0 x 10(5) CFU/mL were 83.1 %-97.0 % in the spiked milk samples. The limit of detection of this biosensor for S. typhimurium cells in the spiked milk samples was 21 CFU/mL. This approach possesses the merits of simple operation, high sensitivity, and low cost, potentially enabling this device to be a lab-on-a-chip for rapid screening of foodborne pathogens.

Salmonella, Shiga toxin-producing Escherichia coli (STEC), and Listeria monocytogenes have been isolated from low water activity foods (LWAF), where they may survive for extended periods. The ready-to-eat nature of many LWAF, such as dried fruits and nuts, warrants effective post-harvest thermal treatment for the reduction of pathogens such as low-temperature, saturated steam, also known as vacuum-assisted steam pasteurization. The objective of this study was to determine reductions of Salmonella, STEC, L. monocytogenes, and a possible surrogate (Pediococcus acidilactici) on dried apricot halves, whole macadamia nuts, and raisins after treatment with vacuum-assisted steam at three temperatures (62 degrees C, 72 degrees C, or 82 degrees C) and multiple time intervals. Bacterial inactivation was variable between commodities, with higher temperatures and longer times necessary to achieve comparable reductions of pathogens on apricot halves and macadamia nuts compared to raisins. Reductions of the tested pathogens were comparable; therefore, one species was not more resistant than the others. Pathogens were reduced by 5-log CFU/g on apricot halves after 20 min at 72 degrees C and after 5 min at 82 degrees C. Longer treatment times were necessary to achieve reductions of each pathogen on macadamia nuts. Pathogens were reduced by nearly 5 log CFU/g on macadamia nuts after 38 min at 72 degrees C (4.6-6.5 log CFU/g) and after 12 min at 82 degrees C (4.9-5.7 log CFU/g). Reductions of pathogens on raisins were achieved at lower temperatures than necessary for the other foods. A 5-log reduction for each of the pathogens (CFU/g) on raisins occurred after 20 min at 62 degrees C and after 5 min at 72 degrees C. Overall, the reductions of the pathogens exceeded those of P. acidilactici on both the dried fruits and macadamia nuts. Statistically significant differences, indicating greater confidence as a conservative surrogate, were observed at lower treatment temperatures. Inactivation kinetics were modeled for each pathogen on each food type and temperature. Bacterial survival was best described by the Weibull model for raisins and macadamia nuts, while the Gompertz model best described reductions on apricot halves according to Akaike information criterion (AIC) and root-mean-square error (RMSE) evaluations. Water activity and moisture content were increased due to the treatments, which could be addressed through implementation of drying steps. Thermal inactivation kinetic models and 5-log reduction parameters can help food processors design and evaluate similar vacuum-assisted steam interventions to comply with FSMA regulations and preventive control plans. However, results or model predictions should not be extrapolated to assume the safety of other types of foods.