Comparison of sampling procedures for recovery of Listeria monocytogenes from stainless steel food contact surfaces.
A number of techniques exist for microbiological sampling of food processing environments in food industries. In the present study the efficacies of nine sampling procedures for the recovery of Listeria monocytogenes from food contact surfaces, including a new sampling device  consisting of a miniroller, were evaluated and compared. A stainless steel table was inoculated with L. monocytogenes strain 935 (serovar 4b, human origin) and L. monocytogenes strain 437/07 (serovar 1/2b, food origin), at 10(5) CFU/100 cm(2). L. monocytogenes  strain 935 was best recovered with the minirollers (recovery of up to 6.27%), while poor recoveries (<0.30%) were obtained with the towel (one-ply composite tissue), alginate swab, metallic swab, and Petrifilm methods. In the case of L. monocytogenes strain 437/07 the replicate organism  detection and counting (RODAC) ALOA contact plates yielded the best recoveries (4.15%), followed by the minirollers (up to 1.52%). Overall, recovery percentages with the minirollers were higher with stomacher homogenization than with Vibromatic agitation. The recovery percentages obtained  for the Listeria strain of human origin were higher than those obtained with the food strain for all sampling procedures except Petrifilm and RODAC ALOA. With the miniroller device coated with wool fiber, the recovery of L. monocytogenes can be improved from 2 to 17 times over  recoveries obtained with the sponge and cotton swab. This is the first report of a miniroller device for microbiological sampling in the available literature. The novel sampling procedure is convenient to apply on surfaces, is cost-effective, and results in better recovery of L. monocytogenes  than do the conventional methods.
Department of Animal Production and Food Science, Veterinary Faculty, University of Zaragoza, c/ Miguel Servet 177, 50013 Zaragoza, Spain.
Diego
D
Gómez
Agustín
A
Ariño
Juan J
JJ
Carramiñana
Carmina
C
Rota
Javier
J
Yangüela
D001422:Bacterial Adhesion; D001431:Bacteriological Techniques / Q000379:methods*; D015169:Colony Count, Microbial / Q000379:methods; D004783:Environmental Microbiology; D004866:Equipment Contamination; D005506:Food Contamination / Q000517:prevention & control*; D005516:Food Microbiology; D006801:Humans; D008089:Listeria monocytogenes / Q000302:isolation & purification* / Q000502:physiology; D013193:Stainless Steel; D013499:Surface Properties
D013193:Stainless Steel