Monitoring hygiene on- and at-line is critical for controlling Listeria monocytogenes during produce processing

The prevalence of Listeria monocytogenes in different types of produce and on processing plant environments was investigated over a 4-year period in a large produce processing plant in Poland. Prevalence of L. monocytogenes was 46% in frozen vegetables and 41.3% in swab samples taken from the plant...

Full description

Saved in:

Bibliographic Details
Published in:	Journal of food protection Vol. 71; no. 4; p. 735
Main Authors:	Pappelbaum, Krystyna, Grif, Katharina, Heller, Ingrid, Wüirzner, Reinhard, Hein, Ingeborg, Ellerbroek, Lueppo, Wagner, Martin
Format:	Journal Article
Language:	English
Published:	United States 01-04-2008
Subjects:	Bacterial Typing Techniques Colony Count, Microbial Electrophoresis, Gel, Pulsed-Field - methods Food Contamination - analysis Food Handling - methods Food Microbiology Food-Processing Industry - standards Genotype Humans Hygiene Listeria monocytogenes - growth & development Poland Prevalence Serotyping Vegetables - microbiology Poland
Online Access:	Get more information
Tags:	Add Tag No Tags, Be the first to tag this record!

Description
Summary:	The prevalence of Listeria monocytogenes in different types of produce and on processing plant environments was investigated over a 4-year period in a large produce processing plant in Poland. Prevalence of L. monocytogenes was 46% in frozen vegetables and 41.3% in swab samples taken from the plant environment. Survival studies using artificial inocula demonstrated that the number of Listeria in frozen produce stored for 100 days did not significantly decrease in relation to the initial contamination level. A subset of 129 L. monocytogenes isolates originating from produce and the plant environment were typed by pulsed-field gel electrophoresis. Seventy-six of these isolates were retyped by ribo- and serotyping. Thirteen pulsotypes and 18 ribotypes were distinguished. Persistent Listeria isolates were found even when cleansing and sanitization was applied on a daily basis. Nine (69.2%) of 13 pulsotypes were recovered during a period of more than 2 years. L. monocytogenes of the same pulsotype was isolated from broccoli sampled directly before and after blanching, thus suggesting that blanching at 92 to 95 degrees C for 4 to 8 min did not result in a Listeria-free product, most likely due to massive recontamination. This finding is of importance since blanching is the only critical control point in produce processing. Cross-contamination between the two lines was demonstrated through isolating L. monocytogenes strains indistinguishable by pulsed-field gel electrophoresis from contaminated gloves and floor surfaces.
ISSN:	0362-028X
DOI:	10.4315/0362-028X-71.4.735