Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 8/4/2006
Publication Date: 8/13/2006
Citation: Munukuru, P., Slade, P.J., Juneja, V.K., Ravishankar, S. 2006. Effects and interactions of temperature, sodium lactate, sodium diacetate and pediocin on the starved cells of listeria monocytogenes. Meeting Abstract. Interpretive Summary:
Technical Abstract: The effects and interactions of temperature (55-60 degrees C), sodium lactate (SL; 0.0-4.8%), sodium diacetate (SDA; 0.0-0.4%) and pediocin (0.0-10000 AU) on the starved cells of L. monocytogenes inoculated on the surface of the frankfurters were investigated, and a predictive model was developed. Central composite design (CCD) was chosen with five different levels of each parameter and twenty-five combinations were obtained. The organism was starved in Butterfield’s phosphate buffer (BPB) at 37 degrees C for 24h. The decimal reduction times were calculated using linear regression. The D-values ranged from 1.41 to 21.77 min. Among the parameters, temperature had the most prominent effect on inactivation of L. monocytogenes. Both SL and SDA showed protective effects at high temperatures by increasing the D-value. SDA inactivated the L. monocytogenes population at lower temperatures by decreasing the D-value from 26.75 to 14.81min. An increase in the D-value (26.75 to 32.96 min) with the increase in pediocin concentration was observed at all temperatures. The interaction of pediocin with SL was significant. With the increase in concentration of pediocin from 0 to 10000 AU, the predicted D-value increased from 14.81 to 20.40 min. Similarly, with the increase in concentration of SL from 0.0 to 4.8%, the predicted D-value increased from 14.81 to 23.77 min. The combined effect of SL and SDA on the predicted D-values was statistically significant (p<0.05). Changes in the protein expression pattern of starved cells of L. monocytogenes inoculated on the surface of frankfurters having different concentrations of SL, SDA, pediocin at different temperatures were analyzed using two dimensional polyacrylamide gel electrophoresis (2-D PAGE). The synthesis of a number of proteins by starved cells of L. monocytogenes exposed to various temperatures was reduced as compared to the control. The number of repressed proteins (26) and novel proteins (23) was more than the number of amplified proteins (9).