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United States Department of Agriculture

Agricultural Research Service

Research Project: MICROBIAL ECOLOGY AND SAFETY OF FRESH ON-FARM ORGANICALLY GROWN PRODUCE Title: Antimicrobial activity of cinnamaldehyde and sporan against enteric pathogens on iceberg lettuce

Authors
item Yossa, Nadine -
item Patel, Jitu
item Millner, Patricia
item Lo, Martin -

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: September 29, 2011
Publication Date: October 20, 2011
Citation: Yossa, N., Patel, J.R., Millner, P.D., Lo, M. 2011. Antimicrobial activity of cinnamaldehyde and sporan against enteric pathogens on iceberg lettuce. [astract]. BARC-UM Fall Symposium. Abstract booklet.

Technical Abstract: Cinnamaldehyde and sporan alone or in combination with acetic acid (20%) were evaluated for their antimicrobial effects against E. coli O157:H7 and Salmonella on lettuce. Iceberg lettuce leaves were cut into pieces (2 x 3 cm) and inoculated with 50 µL (5 droplets of 10µl) cocktail of five strains of Salmonella or nalidixic acid resistant strains of E. coli O157:H7 (7 log cfu/ml). The inoculated leaves were air dried for ca. 30 min, washed with 800ppm cinnamaldehyde in 0.5% Tween (800T), 800ppm and 1000ppm of cinnamaldehyde and sporan alone (800C, 1000C or 800S, 1000S), or in combination with 200ppm acetic acid (1000CV, 1000SV) for 60 s. Treated leaves were spin dried for 60s, packed in a ziplock bags, and analyzed during 14-days storage at 4ºC. Inoculated leaves washed with water were used as control. The samples were plated on XLT4 and CTSMAC-NA agar for Salmonella and E. coli O157:H7, respectively. Color (Hunter L, a, b color classification) and texture (TA-XT2 texture analysis) characteristics of un-inoculated, antimicrobial-treated leaves were analyzed to determine the effects of these natural antimicrobials on produce quality. Treatment with 1000SV and 800T significantly reduced E. coli O157:H7 and Salmonella populations compared to control, 800C, and 1000CV on Iceberg leaves. Combination of acetic acid with sporan further reduced the pathogens; however, the additive effect of acetic acid was not significant. E. coli O157:H7 was more sensitive pathogen to these antimicrobials compared to Salmonella. Bacterial population in antimicrobial-treated leaves decreased significantly during storage. Overall, the texture of treated Iceberg leaves was not significantly different from control. The color of Iceberg leaves treated with antimicrobials was similar (P > 0.05) to control leaves with the exception of lightness of the leaves treated with 800C and 1000C. Results indicate that these natural oils could be used to reduce E. coli O157:H7 and Salmonella on Iceberg lettuce without affecting the texture and the color of lettuce leaves.

Last Modified: 4/18/2014
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