Purpose: This study was to evaluate the dispersion capability of Ethylenediaminetetraacetate with adjuncts against mixed P. fluorescens, L. monocytogenes, and Salmonella Typhimurium based biofilms on simulated industrial food processing plant equipment.
Methods: Bacterial cultures were inoculated in diluted Tryptic Soy Broth (TSB) active flow system for 96 ± 5 h. Once the mature biofilms (> 6.0 log CFU/cm2) were developed the HDPE coupons were removed and rinsed to eliminate any planktonic cells on the surface. This was then followed by exposure to different concentrations and mixtures of the blended compounds. Post dispersant exposure all coupons were added to D/E broth in centrifuge tubes and vortexed with sterile glass beads to suspend the remaining sessile viable cells into solution. From there the solutions were serially diluted, and plated onto Tryptic Soy Agar. Bacterial counts were compared against control coupons to determine log removal.
Results: The experimental combinations show a threshold of 1.622 g/L Ethylenediaminetetraacetate with 0.353 g/L carboxylic polymer in an alkaline solution (> 10 pH) to yield 1.0 log CFU/ cm2 reduction. From the data we were able to determine an optimal concentration of Ethylenediaminetetraacetate for a minimum of a 3 log CFU/cm2 removal and a maximum of a 4 log CFU/cm2 removal at 3.245 g/L with two organic food derived amphoteric surfactants at 0.2457 g/L, 0.312 g/L and a carboxylic polymer at 0.706 g/L.
Significance: The ability to test dispersion technology on food plant biofilms is essential for developing solutions to the problem. In this experiment we were able to test replicate biofilm samples and determine an optimum formulation, which in turn can aid food processors in penetrating and removing persistent pathogenic and spoilage organism based biofilms embedded within their production surfaces.