P1-55 Biofilm Removal from Stainless Steel Surfaces Using Abrasive Mechanical Disruption Combined with Low-volume Electrostatic Application of Sanitizer Spray

Monday, July 23, 2012
Exhibit Hall (Rhode Island Convention Center)
Sherre Chambliss-Bush, University of Georgia, Athens, GA
Mark Harrison, University of Georgia, Athens, GA
S. Edward Law, University of Georgia, Athens, GA
Introduction:  Bacterial biofilms on stainless steel food processing equipment compromise food safety and quality.  Using a combination of two proven sanitation methods, abrasive mechanical disruption and charged electrostatic spraying of sanitizers, may yield an effective low-volume sanitation process to remove biofilms.

Purpose:  As the first step in development of a process that would combine mechanical disruption and spray technology, this study evaluated using abrasive mechanical disruption (abrasive-particulate blasting) and air-assisted electrostatic-induction spray sanitizer application, in tandem, to remove biofilms from stainless steel surfaces. 

Methods:  An abrasive blasting chamber was fabricated so the abrasive blast stream was directed at stainless steel coupons containing Listeria monocytogenes biofilms.  Coupons were positioned at a 60° angle horizontal to the spray and at distances of 8.9 and 24.1 cm from the nozzle. Each coupon was blasted with the abrasive (425-710 μm; 317 g/min) for 10 sec at 40 psi.  Then levulinic acid and sodium dodecyl sulfate (SDS) sanitizer was applied so equal quantities of active ingredient were dispensed using either an air-assisted electrostatic nozzle with droplet charging ON (~ -7 mC/kg charge-to-mass) or with charging OFF or with a conventional hydraulic nozzle.  For accurate spray application, nozzles were attached to a repeatable robotic arm.  The methods were evaluated for the reduction in the population of colony forming units of Listeria monocytogenespreviously inoculated onto the stainless steel surfaces. 

Results: Abrasive mechanical disruption at a nozzle distance of 24.1 cm from the stainless steel surface combined with air-assisted charged spray worked best and reduced the number of biofilm cells by 5.28 logs CFU when using a sanitizer comprised of 6% levulinic acid and 0.6% SDS.   

Significance:  Bacterial biofilms present significant obstacles in food processing environments. Development of a process that can deliver abrasive mechanical disruption and low-volume electrostatic application of sanitizer spray may provide an effective means for biofilm control.